text:
Now showing items 1-20 of 118Next Page
Leng, Ling
1,3-propanediol and caproate co-production through glycerol fermentation and carboxylate chain elongation in mixed culture
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Sewage -- Purification -- Biological treatment
|xxiii, 259 pages : color illustrations
Mixed culture chain elongation of short chain fatty acids (SCFAs) for a medium chain fatty acid (MCFA), caproate, formation is an attractive option for resource recovery in anaerobic wastewater treatment. Caproate, a value-added chemical, is slightly soluble in water and can be used by various industries. Biological production of caproate with ethanol as electron donor has been successfully achieved in anaerobic mixed culture. However, the underlying metabolic pathways of microorganisms except Clostridium kluyveri are not well understood. Another potential electron donor is glycerol which is presently being generated in surplus with the rapid growth of the biodiesel industry. In the current approach, an industrial chemical, 1,3-propanediol (1,3-PDO) is produced from crude glycerol along with a formation of other soluble byproducts including ethanol and SCFAs, which necessitates a significant amount of energy input for separation and purification. To circumvent the energy sink requirement and upcycle both the wastewater treatment process and the biodiesel industry, it is highly beneficial to co-produce caproate from the byproducts of glycerol dissimilation along with 1,3-PDO. At first, thermodynamic and physiological insights gained into the co-production of 1,3-PDO and caproate from glycerol are investigated. Thermodynamics analysis demonstrated that a higher pH range is more favorable when either glycerol or ethanol acting as an electron donor, whereas a high partial pressure (27% at 1 atm) and a low pH (≤ 5.5) are advantageous for caproate formation with hydrogen. With the glycerol-to-acetate molar ratio of 4 and pH of 7, the physiological experiments achieved a co-production of 1,3-PDO and caproate. However, the caproate yield was low and found to be kinetic-limited. Caproate formation was significantly increased by the intermediate ethanol addition with the optimal mono-caproate formation obtained at the ethanol-to-acetate molar ratio of 3. A synergistic relationship was evinced through microbial characterization, resulting in C. kluyveri and some bacteria with function of converting glycerol to SCFAs. Whilst the metabolic pathway of C. kluyveri in carboxylates chain elongation has been discovered, the role of other co-existing microbiomes which promote the elongation remained unclear in mixed culture. Thus, we conducted a fermentation experiment at optimal conditions which is inoculated with fresh anaerobic digestion (AD) sludge and fed with ethanol and acetate. Both 16S rRNA gene-based amplicon and shotgun metagenomics sequencing were employed to elucidate the mixed culture chain elongation by uncovering the microbes and functional pathways. Results revealed a synergistic relationship between C. kluyveri and three co-dominant species Desulfovibrio vulgaris, Fusobacterium varium and Acetoanaerobium sticklandii. The co-existence of these three species were able to boost the carboxylates chain elongation by C. kluyveri. Draft genomes of C. kluyveri, D. vulgaris and A. sticklandii were successfully recovered, revealing that butyrate and caproate can be directly produced from ethanol and acetate by C. kluyveri and indirectly produced through a syntrophic partnership between D. vulgaris and A. sticklandii with hydrogen serving as a reducing equivalent messenger. This study presents evidences of a syntrophic partnership between bacterial species and unveils an intricate and synergistic microbial network in mixed culture carboxylates chain elongation.
Moreover, this study enriched a microbial community capable of efficiently co-producing 1,3-PDO and caproate via glycerol fermentation and carboxylate chain elongation. A co-production of 6.38 mM C 1,3-PDO dˉ¹ and 2.95 mM C caproate d⁻¹ was achieved in a 2-L semi-continuous fermenter with a glycerol-ethanol-acetate stoichiometric ratio of 4:3:1. Microbimes, E. limosum, C. kluyveri and M. senegalense, utilize a unique combination of metabolic pathways to facilitate the above conversion. Based on metagenomics, E. limosum is capable of converting glycerol to 1,3-PDO, ethanol and H2, and also redirecting the electron potential of H2 into acetate via the Wood-Ljungdahl pathway for chain elongation. C. kluyveri worked synergistically with E. limosum by consuming ethanol and acetate for caproate production. M. senegalense encodes for ethanol oxidation to acetate and butyrate, facilitating the caproate production by C. kluyveri. During the transition between fermentation and elongation, an unexpected phenomenon of poly-ß-hydroxybutyrate (PHB) formation and reutilization by M. senegalense was observed, which may be associated with butyrate formation for further caproate generation. Significant ethanol production as an intermediate of glycerol dissimilation and the non-inhibiting level of 1,3-PDO production, which allows the dominance of C. kluyveri, are key to increasing caproate production. Finally, a batch test of glycerol fermentation for the co-production with ethanol self-sufficiency inoculated by the fermenter-enriched microbial community was conducted. This study answers whether the enriched versatile glycerol degrader, E. limosum, could convert glycerol-derived energy to ethanol and H2 in a balance with 1,3-PDO and acetate and whether the ethanol could be further utilized by carpoate producer within the cultivation matrix. In addition, this study also investigated the electron flux of glycerol fermentation and chain elongation. The co-production of 1,3-PDO and caproate was achieved with a favorable glycerol/acetate stoichiometric ratio. Significant ethanol production from glycerol oxidation is the main reason for the caproate production enhancement. A dynamic balance of three dominant microbiomes, E. limosum, M. senegalense, and C. kluyveri, could complete the multiple stages co-production process. E. limosum dominated in the glycerol fermentation phase, while M. senegalense and C. kluyveri worked together for caproate production with ethanol and acetate in the carboxylates chain elongation phase. Redirection of the electron potential of H2 back into acetate for chain elongation by E. limosum and PHB formation and reutilization by M. senegalense were proved by electron flux calculation. The physiological performance and dynamic microbial community disclosed a unique combination of metabolic pathways successfully facilitated the co-production. The knowledge gleaned paves new avenues for both the wastewater treatment process and the biodiesel industry by upcycling their resources recovery.
Ye, Daojun
Accident analyses in Hong Kong : accident blackspot identification, casualty injury severity and before-after analysis
|Dept. of Civil and Environmental Engineering
Traffic accidents -- China -- Hong Kong.
Traffic accident investigation -- China -- Hong Kong.
Traffic safety -- China -- Hong Kong.
Hong Kong Polytechnic University -- Dissertations
|xvi, 113 leaves : col. ill. ; 30 cm.
Road safety is a major concern because of the social and economic costs resulting from traffic crashes. Numerous studies investigating traffic collisions and the resulting costs have been conducted. One important research topic in these studies is accident blackspot identification. The measures of accident frequency and accident rate are commonly adopted as identification criteria. However, identifying accident blackspots based solely on accident frequency or accident rate has been found, in practice, to be inefficient as neither can correctly reveal the extent of accident consequences. For example, high accident frequency does not necessarily result in a large number of fatalities or serious injuries. To supplement the knowledge gained by previous researchers, a new method to rank accident blackspots is proposed in this study. In the proposed blackspot identification method, instead of accident frequency, accident consequences (in terms of injury or accident costs) are considered when identifying accident blackspots. The merit of the proposed method is that it takes not only number of injuries (or accident frequency) but also injury severity (or accident severity) into the consideration. To illustrate the proposed method, a case study was carried out using Hong Kong traffic accident data. The results indicate that adopting accident consequences, such as injury costs, can identify accident blackspots with higher injury costs but the methods of using accident frequency only or the Hong Kong Transport Department's blackspot definition may not be guaranteed.
In view of the importance of casualty injury costs as regards identification of accident blackspots, this feature is further investigated in this study. Focus is on an analysis of the effects of various contributory factors (categorized by environmental, site, and vehicle factors) on the injury severity of driver, passenger and pedestrian casualties and on accident costs in Hong Kong. Binary logistic regression model is adopted to quantify the associations between injury severity of casualties and the contributory factors, while linear regression model is used for modeling the effects of contributory factors on accident costs. A Hong Kong traffic accident dataset for the whole territory from 2007 to 2009 is used in this study to estimate the coefficients of the regression models. The results of the regression models reveal that accident time, rain conditions, speed limits, traffic congestion levels, road types, and vehicle types significantly affect casualty injury severity and accident costs. Each contributory factor has a different effect or a different degree of effect on driver/passenger and pedestrian casualties. A Before-After analysis is also used for investigation of accident effects on traffic speed in this study. Factors affecting the accident effects on traffic speed are firstly identified. Regression models are calibrated with empirical data to quantify the influences of factors on the degree of accident effects. A case study is carried out in which there is a total of 313 accidents occurred on a local urban area of Hong Kong during the study period: from September 2009 to December 2010 together with the corresponding speed data before and after the occurrence of these accidents. From the results of the case study, three factors, namely accident severity, accident time and accident location, were found to significantly affect the degree of accident effects on traffic speed.
Li, Tianji
Advanced analysis and design of axial compression members with high-strength steel
|Dept. of Civil and Environmental Engineering
Steel, High strength.
Steel, Structural.
Composite construction.
Hong Kong Polytechnic University -- Dissertations
|xxviii, 298 pages : illustrations (some color)
High-strength steel is a term usually applied to specific types of steel that have a design yield strength larger than 460 MPa, distinguishing it from the other types of steel having lower strength. Its adoption has become popular in the past decade, initiating certain benefits in fabrication, construction, cost, and so on. Not only does using high-strength steel dramatically reduce the section sizes of members associated with material consumption and member weight, it also considerably alleviates the difficulties in buildmanship and accelerates construction. This can significantly benefit construction in high density urban areas, such as Hong Kong, Shanghai, and New York, where the labor cost is usually more expensive than the material cost. Consequentially, high-strength steel can be viewed as environmental friendly because its use reduces material consumption, thereby decreasing carbon dioxide release. Although high-strength steel is mass-produced and is widely used in mechanical engineering, its utilization in building construction is still under exploration due to the lack of consummate design and analysis approaches. The current design codes for steel columns used worldwide, e.g., ANSI/AISC 360-10, Eurocode 3 Part 1-1, Hong Kong Code 2011, and China GB50017-2003, mostly provide the formulae and charts for steel with a design yield strength less than 460 MPa, resulting in obstacles in the design and application of high-strength steel members. Eurocode 3 Part 1-12 simply extends the use of high-strength steel to grade S 700. This thesis aims to propose a direct analysis and design approach for high-strength steel members, thereby eliminating the use of the tedious charts and formulae associated with linear elastic assumptions. By using high-strength steel, the sectional sizes of members can be dramatically reduced and the stability problems associated with the second-order effects would be dominated, which should be properly reflected in the design. In the present study, the pointwise equilibrium polynomial (PEP) element is employed to model the beam-column members and to simulate the P-δ effects due to initial member curvatures. Adopting the high-order shape function for the PEP element and considering the bowing effects, one element per member is sufficient and accurate for nonlinear elastic analysis. Therefore, member design can be simply executed by checking the section strength at critical locations. For a more accurate representation of the section capacity, the sectional yield surfaces are introduced, which are expressed by a series of strength points in a bi-axial loading space. Two types of surfaces are presented: initial and failure surfaces. These are generated by a cross-sectional analysis technique based on the quasi-Newton algorithm. The sections are automatically meshed into small triangular fibers. This method is valid for arbitrary shapes of the steel sections. The elastic and plastic limit states of a section can be described by the initial yield and failure surfaces, respectively. To explicitly consider the influences of residual stress, the cross-sectional analysis technique is further developed to take this effect into account. The initial stress inherent in a section is reflected by introducing the residual strains applied to each fiber; therefore, the numerical algorithm can be easily modified on the basis of the current available programs.
Consequentially, residual stress models are vital for the cross section analysis. In real-time applications, Q690 high-strength steel shows a non-negligible potential in applications; however, its residual stress distribution patterns are still being explored and they are seldom reported in the available literature. In this thesis, the magnitudes and distributions of six box and H columns, fabricated by Q690 high-strength steel, will be investigated using the sectioning method. The residual stress patterns on column sections are examined and presented. To simplify the analysis, straight-line models of Q690 high-strength steel are first proposed on the basis of the experimental investigations, which can be further applied to the analysis of the other sections with ranged width-to-thickness or height-to-thickness ratios. To fulfill the design requirements for simulating the structural behaviors under extreme scenarios, such as progressive collapse analysis, performance-based seismic design, the vital effects inherent to the structural members should be reflected. The P-Δand P-δ effects related to the frame out-of-plumpness and initial member curvatures, respectively, are directly considered by employing the curved PEP element with the high-order shape function. The influence of residual stress is reflected by explicitly calculating in the cross-section analysis. In addition, a refined plastic hinge model is introduced in order to consider the gradually yielding behaviors at the critical sections. From the present study, it can be observed that the residual stress exerts certain influences on controlling the sectional elastic limit that might cause the fiber to start yielding at a low stress state. Differing from the conventional method, where the equivalent imperfection is adopted combing initial member curvatures and residual stresses, the proposed method separately considers these two vital effects. Therefore, the design can be more accurate, safe, and economical thereby eliminating the empirical and uncertain considerations found in the conventional design method. To verify the accuracy and versatility of the proposed method, six fabricated box columns and six welded H columns with different slenderness ratios ranging from 30 to 70 are axially-loaded and studied. All of the columns were prepared by the flame-cut Q690 steel plates with a thickness equal to 16 mm. The numerical simulations of the specimens obtained by the proposed method are presented and compared with the outcomes of the experiments, showing satisfactory results in the comparisons in terms of tracing the load vs. deflection and predicting the ultimate strength. Extensive research studying the overall buckling behavior of the Q690 columns with different slenderness ratios is conducted, and 132 nos. and 192 nos. columns with box and H sections, respectively, are analyzed by the proposed method. These results are compared with the conventional buckling curves in codes, e.g., GB 50017-2003, Eurocode 3, and ANSI/AISC 360-10. The comparisons show that the axial strengths of the high-strength columns are underestimated, especially for the members with low slenderness ratios. This further proves the importance and necessity of developing an efficient and practical method for the design of high-strength members; otherwise, the material utilization efficiency could be reduced. To propose an efficient and practical method for the design of high-strength steel members, a second-order design method, based on ANSI/AISC 360-10, is proposed by revising the stiffness reduction factor for a more proper reflection of the residual stress. The optimal design formulae for high-strength steel members are proposed on the basis of an extensive study comprised of over 300 columns. In this thesis, an efficient advanced analysis and practical second-order design method for structures with high-strength steel members is proposed. A cross-section analysis technique with an explicit consideration of residual stresses is developed. Strength-line models for describing the residual stress patterns of H and box sections fabricated by Q690 steel plates are first proposed. The curved PEP element is employed to simulate the initial member curvature and capture the large deflection effect. A refined plastic hinge model using the sectional surfaces is used to model the inelastic behavior at the gradually yielding sections. Twelve columns are experimentally investigated to verify the proposed theory and extensive research on over 300 nos. columns is conducted. A refined second-order design approach, based on ANSI/AISC 360-10, for high-strength steel members is proposed.
Peng, Yixin
Aerodynamic characteristics and optimal pitch control of high-solidity straight-bladed vertical axis wind turbines
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Vertical axis wind turbines
Wind turbines -- Design and construction
Wind turbines -- Aerodynamics
|xxii, 305 pages : color illustrations
Gradual depletion of fossil energy sources arouses worldwide attention to renewable energy sources, among which wind energy is one of the most promising alternatives. In the past few decades, as challenging problems on enlarging the scale of horizontal axis wind turbines (HAWTs) become more prominent, vertical axis wind turbines (VAWTs) attract attention in both fields of academic and industry. However, while the VAWTs have the primary advantages of being omnidirectional, insensitive to turbulent wind, having a simple structure, less aerodynamic noises and easy maintenance, they also suffer from the problems of comparatively low power coefficient and unsatisfactory self-start ability. Straight-bladed VAWTs (SBVAWTs) are of potential to gain a better power efficiency by variable-pitch techniques, and among different types of SBVAWTs, the high-solidity SBVAWTs could be of value in application for their comparatively good self-start performance and low operational speed. This thesis therefore mainly investigates aerodynamic characteristics and self-start performance of high-solidity SBVAWT and establishes a practical pitch control technology for enhancing power generation of high-solidity SBVAWTs through a series of wind tunnel tests, computational fluid dynamics (CFD) simulations and analytical analyses. To this end, a wind tunnel test system, which can directly measure the aerodynamic force on the blades of a SBVAWT, is developed. Systematic wind tunnel tests on the aerodynamic forces on the blades of both a moderate-solidity and a high-solidity SBVAWTs are carried out. Both tangential and normal aerodynamic forces are measured for different tip speed ratios and incoming wind speeds. Characteristics of these aerodynamic forces are analyzed and discussed. The aerodynamic force data collected from wind tunnel tests will be used as a database for establishing appropriate analytical tools for analyzing high-solidity SBVAWTs and for validating the reliability of analytical tools and computational fluids dynamics (CFD) simulations in the subsequent studies. A CFD-based model, using 2.5D large eddy simulation (LES) method, for the high-solidity SBVAWT with fixed-pitch is established. The reliability of the 2.5D LES simulation is by the comparison between the simulation result and the test result. The flow field characteristics around the high-solidity and moderate-solidity SBVAWTs are investigated. Based on the details of the flow field around the rotor, the variations of the aerodynamic forces are explained and the mechanisms of aerodynamic forces on the blades are explored.
After assessing the availability of the current analytical model to the high-solidity SBVAWT, a test-based double disk multiple stream-tube model (DMST), which is able to predict and evaluate the aerodynamic forces on blades of the high-solidity SBVAWT, is derived and verified by the experimental data. Novel method of establishing the attack angle-dynamic aerodynamic force coefficient relationship based on test data is proposed, which is then applied to the DMST model to develop it to be a test-based DMST model. The aerodynamic forces estimation from the proposed test-based DMST model are verified by the experimental data and the results manifest that the testbased DMST model could predict the aerodynamic forces on blades of the high-solidity SBVAWT with higher accuracy than the existing DMST models. Although the attack angle-dynamic anglenamic force coefficient relationship is obtained from the tested high-solidity SBVAWT, the method to establish this relationship proposed in this thesis is applicable to any other SBVAWTs. Therefore, it is of value in design and optimization of the SBVAWTs. An algorithm to search the optimal pitch angles for the SBVAWTs is also proposed. It takes maximizing the tangential force as the objective function, rather than limiting the forms of pitch curves as most of the current relevant researches. Based on the test-based DMST, the optimal pitch angles are searched at each stream-tube and finally composed as an optimal pitch curve after completing searching at the rotor plane. Optimal pitch curves with tip-speed ratios (TSRs) from 0.7 to 2.2 are computed and obtained, based on which an optimal pitch function is then established for the implementation to the control devices. Several mathematic constraints for practical implementations are proposed in the establishment of optimal pitch function. It is determined to be the function of azimuth angle and TSR, whose parameters are fitted based on the calculated optimal pitch curves. Comparison results of power coefficients indicate that the power coefficients of the high-solidity SBVAWT could be increased considerably with either the calculated optimal pitch curves or the optimal pitch function. CFD simulation with 2.5D LES method is conducted to reveal the flow field features of the variable-pitch high-solidity SBVAWT and to analyse the mechanism of power coefficient enhancement. Details of flow field characteristics are depicted and demonstrated that compared to the high-solidity SBVAWT with fixed-pitch, the high-solidity SBVAWT with the proposed optimal pitch function could diminish the scale of vortex forming in the upwind area and postpone the dynamic stall occurrence to increase the contributed tangential force coefficients and eventually enhance the power efficiency. A novel design of the variable-pitch control scheme with the proposed optimal pitch to the high-solidity SBVAWT is proposed and realized for a prototype of the variable-pitch high-solidity SBVAWT. The pitch angles of three blades are controlled by a control disc with a designed rail and three connecting rods. The designed rail could be changed to make it adaptive to any other pitch control scheme or any other types of SBVAWT. Wind tunnel tests that focus on the power output of the fixed and variable-pitch high-solidity SBVAWT are carried out accordingly. A sinusoidal pitch scheme is also used for comparison. Test results indicate that the power coefficient could be enhanced prominently with the proposed optimal pitch function and demonstrate that the proposed design of variable-pitch control scheme is feasible, functional and effective.
Lee, Sin Hang
Air pollution exposure and the health impact on school children in Asian cities
|Dept. of Civil and Environmental Engineering
School children -- Health and hygiene -- Asia.
Air -- Pollution -- Health aspects -- Asia.
Transportation -- Environmental aspects -- Asia.
Hong Kong Polytechnic University -- Dissertations
|xiii, 155 pages : color illustrations
|This study relates the pulmonary function of school children to the air quality they are exposed to inside and outside classrooms as well as on route to school using various public transport modes and walking in three Asian cities. The study focuses on primary Grades 5 and 6 pupils from schools in Hong Kong, Kathmandu, Nepal and Hanoi, Vietnam. A health record questionnaire was distributed to the schools and completed by the parents of sampled pupils. Each sampled pupil also had to fill in the daily travelling activity logbook for a week. They were also required to take a pulmonary function test. The living style in the three sampled cities is very different. Most of the sampled students travelled to school on foot in Hong Kong and Nepal; however, 70% of the sampled students cycled to school in Vietnam. Beside the mode of transport to and from school, there are also large differences in the percentage of children keeping pets at home between the cities. In Hong Kong, only 13% of sampled students reported keeping pets at home, which is the lowest percentage of the three cities. Kathmandu, Nepal reported the highest percentage with 42.6% of sampled students keeping pets at home and Vietnam reported 37.5%. Statistical ANCOVA analyses were applied for testing the significance of the differences. The results showed that boys had a significantly better pulmonary function value than girls. The result is similar to previous researches. The pulmonary function values of the three sampled cities were further compared by ANCOVA. The result shows that Nepal has the poorest performance for children's lung function. In Hong Kong, the ANCOVA results showed that there is a significant difference in the pupil's lung function according to mode of transportation. Therefore, the air sampling was carried out inside the vehicles along the routes to school in the morning and returning home in the evening. The air sampling results revealed that those pupils who travelled by school buses had the poorest pulmonary function. This may well be explained by the poor air quality in school buses. The best air quality was found on trains. Children who travelled by rail to school had the best pulmonary function performance. Stepwise regression was further applied to identify the significant contributors to pulmonary function. The parameters "family member smokes inside home", "height", "gender" and "weight" were shown to have significant contributions to the lung function value. Examining the change of R-square, we identified that "family member smokes inside home has the major contribution to the model, representing around 1325% information of the model. Finally a statistical regression model was developed to quantify the effect of each factor influencing pulmonary function. "Family member smoking inside home" is great effect on allergic rhinitis. In Nepal, 326 students were sampled in ten schools. Statistical ANCOVA showed that there was a significant difference in children's pulmonary function among sampled schools and gender. A negative correlation between CO concentration and children's pulmonary function was identified. In Vietnam, 511 students were sampled in ten schools. The results were similar to the Nepal study in that a significant difference was found in pulmonary function (FEV1) among the sampled schools and children keeping furry pet at home in the last 12 months. The correlation between pulmonary function and indoor air quality showed negatively for all indoor sampled air pollutants (PM10, CO and TVOC), indicating the air quality had significant impacts on children's pulmonary function.
Tang, Lu
Anaerobic fluidized-bed membrane bioreactor with greywater for water reuse
|Dept. of Civil and Environmental Engineering
Sewage -- Purification -- Anaerobic treatment.
Hong Kong Polytechnic University -- Dissertations
|ix, 30 pages : illustrations (some color)
|Today, water shortage, energy security, and climate change are three of the most significant global issues that need to be addressed. In order to solve these issues, anaerobic treatment with greywater for water reuse, energy recovery, and reduction of carbon emission has been proposed. Although anaerobic treatment with greywater has shown its promising potential to solve these issues, the bottleneck of this process is poor degradability of anionic surfactants significantly containing in greywater. The objective of this paper was to study the removal/adsorption performance of a common anionic surfactant, sodium dodecyl sulfate (SDS), existing in greywater with anaerobic treatment process. This process is called anaerobic fluidized bed membrane bioreactor (AFMBR) with granular activated carbon (GAC) inside the reactor. In this study, GAC was used as fluidized medium to support biological growth. The performance of AFMBR and adsorption capacity of GAC was studied. GAC adsorption capacity was tested onto both SDS and glycerol. GAC adsorption capacity onto SDS can reach 55 mg g⁻¹, while for glycerol it can only reach 3.5 mg g⁻¹ which can be negligible in the reactor. Total COD and SDS concentration was measured from permeate effluent daily and twice a week, providing a removal efficiency of 91% and 98%, respectively. In all those removed SDS concentration, 20% were degraded by biological anaerobically, 80% of total removed SDS were adsorbed by GAC and almost 98% of removed glycerol were biodegraded, just 2% of removed glycerol can be adsorbed by GAC. In this lab-scale treatment, effluent COD and SDS concentration was really low, at a value of 25±5 mg g⁻¹ and lower than 2 mg g⁻¹, respectively. Greywater can be reused in many ways, such as toilet flushing in coastal city, car washing, irrigation and even for drinking. We envision that this AFMBR within GAC process could serve as a cost-efficient method on anionic surfactants removal as a treatment of anaerobically-treated greywater for reuse.
Yu, Huayang
Application of warm asphalt rubber as a sustainable paving material : component interaction mechanism investigation and performance characterization
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Asphalt -- Additives
|xxii, 187 pages : color illustrations
Asphalt rubber (AR), which is defined as raw bitumen modified by no less than 15% of crumb rubber modifier (CRM) by total binder weight, has gained increasing interest in recent years, due to its excellent mechanical performance and tyre-road noise reduction function. However, its high viscosity leads to the concern on its workability. Conventionally, the construction temperatures of AR mixtures are 30-50 °C higher than those of conventional mixtures, resulting in more energy consumption and higher construction emission. Warm mix asphalt (WMA) is a sustainable paving technology which can decrease the construction temperature of asphalt mixtures, reducing energy consumption, emission and odours during asphalt pavement construction. Correspondingly, it is an ideal solution to alleviate the workability concern of AR mixtures, thus producing durable and low-noise pavements that are also low-emissive during construction. However, research on warm asphalt rubber (WAR), especially on the component interaction mechanism of AR, is relatively limited despite its significant potential merits. Therefore, this dissertation research aims to systematically investigate the component interaction mechanism of WAR and analyse the effects of WMA additives on the workability and performance of AR. To achieve this objective, various types of WMA additives, including foaming additives (Aspha-min), organic additives (56# commercial wax and Sasobit) and chemical additives (Evotherm-DAT and Evotherm-3G), were incorporated to AR binder and mixture, followed by rheological, mechanical and chemical analyses. Rheological analysis on WAR binders involved the evaluation of penetration, softening point, viscosity, rutting factor, fatigue factor and low temperature stiffness. The analysis results showed that all non-foaming WMA additives were effective in improving the workability of AR binder, but provided various effects on other rheological properties. Only Sasobit was found to further improve the rutting resistance of AR binder. All non-foaming additives led to slightly poorer fatigue and low-temperature cracking resistance. When Sasobit and Evotherm-DAT were used together, the rheological properties were significantly compromised.
Chemical analysis investigated the effects of different WMA additives on the thermal behaviours, infrared spectra and asphalt four fraction distributions of the AR binders. The Fourier Transform Infrared Spectroscopy (FTIR) test results indicated that the variance in FTIR spectrum is mainly caused by the chemical nature of WMA additives, while the thermal test results proved that not only the light fractions of the base asphalt, but also part of the WMA additives, penetrates into CRM particles during the mixing process of AR binder. Besides, WMA additives have positive effect on promoting the interaction between CRM and base asphalt. Several mixing procedures of WAR binders were also proposed and their effects on WAR's rheological and chemical properties were evaluated. It was found that incorporating Evotherm-DAT, Sasobit and 56# paraffin wax at an earlier stage during the WAR preparation process has very marginal negative effect on the rheological properties compared to the conventional mixing procedure. However, the chemical analysis on the liquid phase of wax-based WAR binders indicated that the mixing procedure affected the interaction within WAR binder. The wax content of the liquid phase of the WARs prepared by the direct mixing method is lower than that prepared by the conventional method. The mechanical tests on WAR mixtures included the evaluation of mixture compactability, moisture susceptibility, stiffness modulus, dynamic modulus, and rutting and fatigue resistance. Owing to WMA additives, the mixing temperatures of all WAR mixtures studied in this research can be 16°C lower than that of their corresponding hot AR mixtures, achieving a similar compaction level. The stiffness modulus and dynamic modulus are influenced by the type of WMA additives. All WAR mixtures exhibited acceptable moisture susceptibility, rutting resistance and fatigue resistance. Among different WMA additives, Sasobit provided the most satisfying performance of AR mixture. It further enhanced the rutting resistance and had limited negative influence on other mechanical properties. In general, the results of the mixture mechanical analyses are consistent with those of the binder rheological analysis, except for fatigue resistance. Finally, it is believed that among the selected WMA additives in this research, Sasobit works best with AR binder and mixture. It is also expected that the data generated in the present research would be helpful to understand the overall performance of WAR binders and mixtures.
Li, Xiangmin
Automatic incident detection under no-rain and rain conditions
|Dept. of Civil and Environmental Engineering
Traffic flow -- Mathematical models.
Traffic flow -- Data processing.
Hong Kong Polytechnic University -- Dissertations
|xxi, 141 pages : illustrations ; 30 cm
This research presented in this thesis focuses on the development of automatic incident detection (AID) algorithms for use under no-rain and rain conditions. A new extended standard normal deviate (ESND) algorithm is proposed by extending the widely used standard normal deviate (SND) algorithm. The previous SND algorithm is modified with two extensions. In the first extension, the weighting method is adopted to enhance the reliability of detection results. In the second extension, the variation of input data within sampling periods is restricted to reduce false alarms for incident detection. The algorithm development is on the basis of the available data collected originally for journey time estimation purpose in Hong Kong. These data have been collected by both video traffic detectors and automatic vehicle identification readers. Instead of installing more expensive traffic detectors, the proposed ESND algorithm has proved feasible in effective traffic incident detection, with the use of the available data collected originally for journey time estimation purpose. In addition to the widely used traffic stream parameters such as traffic speed, flow and occupancy for incident detection, two new traffic stream parameters are proposed as incident indicators. They are (1) the coefficient of variation of speed at the upstream detector and (2) the correlation coefficient of speeds of two adjacent detectors. Traffic data collected from both single detector stations and dual detector stations are selected as the inputs for the proposed ESND algorithm. The proposed ESND algorithm is firstly extended to be a flow-dependent ESND algorithm for incident detection under no-rain conditions. The preincident traffic flow condition is considered explicitly in the detection logic to improve the detection performance under various traffic flow conditions. Historical traffic and incident data on a selected urban road section in Hong Kong are used for calibration and validation of the proposed flow-dependent ESND algorithm. Five existing AID algorithms are selected and calibrated for comparison with the proposed flow-dependent ESND algorithm with the use of the available data collected for journey time estimation purpose on the previously selected urban road section under no-rain conditions. The comparison results show that the proposed algorithm outperforms the five selected AID algorithms in terms of the detection rate, false alarm rate and mean time to detect.
The proposed ESND algorithm is then extended to be a more generalized flow-rain-dependent ESND algorithm for incident detection under both no-rain and rain conditions. The rain condition together with the preincident traffic condition are considered explicitly in detection threshold determination. Instead of the traffic flow, the volume/capacity ratio is adopted to indicate the preincident traffic condition. Compared to the discrete detection thresholds in the previous flow-dependent AID algorithms, continuous detection thresholds are adopted in the proposed flow-rain-dependent ESND algorithm. These continuous detection thresholds are generated by a generalized detection threshold function in which both preincident volume/capacity ratio and rainfall intensity are modeled. The proposed flow-rain-dependent ESND algorithm is applied to the urban road network under the Hong Kong Journey Time Indication System (JTIS) in order to examine the detection performance of the proposed algorithm on a territory-wide basis. In this research, the proposed flow-rain-dependent ESND algorithm is calibrated on the basis of available Hong Kong historical traffic, incident and rainfall intensity data collected on the urban road network under the JTIS. The detection performance of the proposed flow-rain-dependent ESND algorithm outperforms the flow-dependent ESND algorithm and the five selected AID algorithms on a territory-wide basis. It is shown in this research that the proposed flow-dependent ESND algorithm performed satisfactorily for incident detection in urban areas even when data are collected for journey time estimation purpose only. The proposed flow-rain-dependent ESND algorithm could be used for incident detection under both no-rain and rain conditions. This is of importance to cities with substantial rainfalls similar to Hong Kong.
Wang, Youwu
Bayesian-based methodology for progressive structural health evaluation and prediction by use of monitoring data
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Structural health monitoring
|xix, 198 pages : color illustrations
Despite the continuous evolution and development in the field of structural health monitoring (SHM), interpreting the huge amount of monitoring data from an SHM system to obtain useful information on structural conditions remains a challenge. Furthermore, due to the complexity of structures, measurement noise, inherent uncertainties in measured data and analytical methods, precise models which reflect the actual structural systems are difficult to create. In this regard, this thesis presents novel model-free data-interpretation methodologies within the Bayesian framework for structural health evaluation and prediction. The first part of the thesis is aimed at conducting SHM-based structural condition assessment using Bayesian linear model (BLM) and Bayesian generalized linear model (BGLM). For condition assessment of bridge expansion joints, the relationship pattern between thermal movement of expansion joints and effective temperature of bridge deck is quantified using BLM and long-term monitoring data. The model parameters, model error and their associated uncertainties are estimated by analytical and simulation algorithms. With the established BLM, an anomaly index is defined to evaluate the failure probability of the expansion joints. The maximum and minimum displacements of the expansion joints under design extreme temperatures are predicted and compared with the design allowable values for validation. Then the BLM is extended to BGLM for assessing wind-induced displacement responses of instrumented bridge. With the monitoring data of displacement and wind during typhoons, the correlation pattern between wind-induced displacement and wind speed/direction is explored. The crucial issue of optimizing model structure is dealt with by employing Bayesian model class selection, in terms of maximizing the log-likelihood function. Based on the established model, the bridge displacement responses and the associated confidence intervals under wind speed at serviceability limit state (SLS) are predicted and compared with the design allowable values for validation.
In the second part, Bayesian inference-based dynamical linear models (BDLM) are developed for prognosis and damage detection by using the time series of structural response. Firstly, different step ahead predictions by various models considering different component forms, such as trend, seasonal and regression components, are evaluated and compared in accordance with three model criteria. After the most suitable model is determined, a novel detection technique based on the forecasting of BDLM is proposed for local anomaly diagnosis. An index called Bayes factor is introduced for outlier detection. It is carried out by checking the current observation against the forecasting distribution (yielded from the BDLM at current moment) as well as against an alternative model (whose mean value is shifted by a prescribed offset). The detection rule is that if the alternative model better fits the actual observation, a potential outlier is detected. Then, the logic of outlier detection is extended to distinguish between the single outlier and the appearance of a change through defining the cumulative Bayes factors, which can diagnose the anomaly of local component under extreme events or due to structural damage. Finally, Bayesian hypothesis testing is conducted by comparing the time series of structural response before and after the change point to make a judgement on whether the structure is healthy. Two case studies using the in-service monitoring data from a high-speed train and the data from a bridge benchmark problem are provided to show the applicability and effectiveness of the proposed method.
Bai, Yulei
Behavior and modeling of RC columns confined with large-rupture strain FRP composites
|Dept. of Civil and Environmental Engineering
Fiber reinforced concrete.
Fiber reinforced plastics.
Columns, Concrete.
Hong Kong Polytechnic University -- Dissertations
|279 p. : ill. ; 30 cm.
A very popular application of FRP composites is as external jacket for the seismic strengthening/retrofit of RC columns. It has been well established that FRP confinement can enhance both the strength and ductility of RC columns. The three common FRP composites used in column strengthening/retrofit include carbon FRP (CFRP), glass FRP (GFRP) and aramid FRP (AFRP) composites, which are referred to as conventional FRPs in this thesis. These FRP composites have a linear elastic stress-strain response with brittle rupture failure at a small rupture strain (typically around or less than 1.5% for CFRP, around or less than 2.5% for GFRP and around or less than 3% for AFRP). For seismic retrofit applications, an FRP jacket with a larger hoop rupture strain is generally beneficial as it leads to more ductile behavior and greater energy absorption with the same degree of strength enhancement. In recent years, a new category of FRP composites has emerged as an alternative to conventional FRP composites for the seismic retrofit of RC columns. These FRPs are made of new materials such as Polythylene Naphthalate (PEN) or Polyethylene Terephthalate (PET) fibers which possess a large rupture strain (LRS) (usually larger than 5%) but a relatively low elastic modulus. Compared to conventional FRPs, these LRS FRPs are cheaper and more environmentally friendly because they are usually made from recycled materials (e.g., waste plastic bottles). Therefore, the use of LRS FRPs is expected to lead to a more economical and ductile solution for seismic retrofit applications. The low elastic modulus of these new FRP composites is generally not a problem because it can be compensated by the use of a thicker FRP jacket. Against this background, this thesis is concerned with the investigation of application of the LRS FRP in seismic strengthening / retrofit of RC columns. This thesis presents a systematic study covering the behavior and modeling of RC columns confined with LRS FRP. This thesis is composed of three parts: (1) behavior and modeling of LRS FRP-confined plain concrete; (2) interaction between the external FRP jackets and internal longitudinal reinforcing bars in FRP-confined RC columns; (3) behavior and modeling of FRP-confined RC columns subjected to combined constant axial load and cyclic lateral load. In the first part of this thesis, an experimental study on LRS FRP-confined plain concrete cylinders subjected to monotonic axial compression was conducted. Results from tensile coupon tests for LRS FRP indicated that LRS FRP fibers possess an approximately bilinear tensile stress-strain relationship, which has a significant effect on the axial compressive stress-strain behavior of FRP-confined concrete. A recent confinement model for conventional FRPs was compared with the present test results, indicating that the model significantly overestimates the ultimate axial strain. A modified version of the model was then presented to provide more accurate predictions for the test results. Furthermore, tests on LRS FRP-confined plain concrete columns under cyclic axial compression were carried out. A cyclic compressive stress-strain model for LRS FRP-confined concrete was developed by combining the proposed monotonic model for the envelope curve and a recent model for the cyclic unloading/reloading rules. In the second part of this thesis, interaction between the external FRP jacket and the internal longitudinal reinforcing bars in FRP-confined RC columns was investigated. It is well known that in FRP-confined RC columns, the lateral deflection of longitudinal reinforcing bars influences the performance of the external FRP jacket (i.e., mainly the rupture strain efficiency and non-uniform strain distribution along the column section circumference), and vice visa. In this study, the buckling behavior of longitudinal reinforcing bars, which is believed to be the most representative phenomenon for the interaction mechanism and the major reason for the rupture strain efficiency and non-uniform strain distribution of FRP jacket along the column section circumference, was studied through both experimental and numerical methods.
At the beginning of the second part, experimental studies on FRP-confined RC columns subjected to monotonic and cyclic axial compression were presented. For the FRP-confined RC columns under monotonic axial loading, the contribution of longitudinal reinforcing bars could be separated by subtracting the total axial load by the contribution of the corresponding FRP-confined plain concrete columns. A curved beam model was utilized to evaluate the confining stiffness provided by the external FRP jackets on the longitudinal reinforcing bars. Then a "beam with springs" model was proposed to calculate the monotonic compressive stress-strain response of longitudinal reinforcing bars in FRP-confined RC columns. Favorable agreement between the predicted stress-strain curves and test results validated the accuracy and applicability of the proposed model. Furthermore, parametric studies based on the proposed "beam with springs" model were conducted to probe into the influence of the three main factors on the compressive stress-strain curves of longitudinal reinforcing bars. An empirical model was proposed to describe the monotonic compressive stress-strain response of longitudinal reinforcing bars in FRP-confined RC columns through the least-squares regression method. The proposed monotonic compressive stress-strain model, together with a monotonic tensile stress-strain model and the Menegotto-Pinto model accounting for the cyclic loops, comprises a complete stress-strain model for reinforcing bars under cyclic loading. The proposed stress-strain model for laterally supported reinforcing bars and a simplified version for the proposed model for FRP-confined plain concrete under cyclic compression were implemented into the OpenSees software platform. Comparisons between test results and results predicted by OpenSees verified the accuracy of the proposed reinforcing steel model. Results from OpenSees simulations also demonstrated that the plastic strains of plain concrete, reinforcing bars, and the whole RC column are inconsistent with each other: when the whole RC column is unloaded to zero, the FRP-confined plain concrete tends to be in compression, while the reinforcing bars tend to be in tension. The third part of this thesis presented an experimental study on seismic behavior of RC columns confined with FRP composites. Three RC columns strengthened with PEN FRP composites, were tested under combined constant axial loading and cyclic lateral loading. The results were compared with those of three conventional CFRP-confined RC columns and one control RC column. Hysteretic responses and failure mode of these columns, as well as the strain evolution histories of longitudinal reinforcing bars and external FRP jackets, were discussed in detail. Numerical simulations based on a fiber element model were conducted to reproduce the test results, and close predictions could be obtained by numerical simulations.
Fang, Xiaoliang
Behavior of FRP-confined self-compacting concrete
|Dept. of Civil and Environmental Engineering
Fiber reinforced plastics.
Fiber reinforced concrete.
Tubular steel structures.
Columns, Iron and steel.
Hong Kong Polytechnic University -- Dissertations
|xv, 100 leaves : color illustrations ; 30 cm
With the advantages of excellent corrosion resistance and high strength-to-weight ratios, FRP composites are being increasingly used in both structural retrofit/strengthening and new construction. In the new construction area, hybrid FRP-concrete members based on filament-wound FRP confining tubes with fibers oriented close to the hoop direction have great potential in practical applications. Such members include concrete-filled FRP tubes with longitudinal internal steel reinforcement and FRP-steel-concrete double-skin tubular columns (DSTCs). This thesis is concerned with the behavior of self-compacting concrete (SCC) used to fill FRP confining tubes to form hybrid members of various forms. In such hybrid members, the use of SCC is highly attractive as it simplifies the task of construction and facilitates the proper flow of concrete into small spaces (e.g. the annular space in a DSTC). While the substitutability of SCC for normal concrete (NC) is widely accepted based on numerous studies, little knowledge exists on the differences between SCC and NC when they are under substantial confinement from an FRP tube. As extensive work has been published on FRP-confined NC, this thesis presents a systematic study on the behavior of FRP-confined SCC as found in concrete-filled FRP confining tubes, and compares this behavior with that of FRP-confined NC.
Following a literature review that identifies the existing knowledge gaps, this thesis presents an experimental study on the behavior of SCC confined by an FRP wrap under axial compression. The FRP wrap had fibers oriented only in the hoop direction and was formed on the concrete column after the concrete had hardened. As a result, these tests did not involve a number of complicating effects associated with concrete-filled FRP tubes, including the complexity in determining the hoop elastic modulus, the effect of the axial stiffness of the FRP tube and the shrinkage of the SCC. The test results are carefully presented and compared with an accurate stress-strain model for FRP-confined NC (i.e. Jiang and Teng{174}s model). The comparisons indicate that the model can provide reasonably close predictions for the axial stress-axial strain behavior of moderately-confined and heavily-confined normal strength SCC and heavily-confined high strength SCC but fails to make close predictions for the axial stress-axial strain behavior of weakly-confined SCC and moderately-confined high strength SCC. In addition, the model does not provide accurate predictions for the lateral expansion of FRP-confined SCC. The thesis next presents a study on the behavior of SCC in glass FRP (GFRP) tubes by testing a series of SCC-filled GFRP tubes under axial compression. An expansive admixture was included in the SCC mix for some of the specimens to compensate for the shrinkage of SCC. The test results of SCC-filled GFRP tubes indicate that a suitable amount of expansive admixture should be used in such columns to create a better confinement condition. The test results are again compared with predictions from Jiang and Teng's model developed for FRP-confined NC. These comparisons again show that the lateral expansion behavior of SCC confined by GFRP tubes cannot be properly predicted by the model, which however can predict the axial stress-axial strain behavior of SCC confined by GFRP tubes reasonably closely, particularly when the shrinkage of SCC is compensated for through the use of an expansive admixture.
Zhang, Yue-xin
Behavior of large-size FRP-jacketed circular and rectangular reinforced concrete columns
|Dept. of Civil and Environmental Engineering
Fiber reinforced concrete.
Fiber reinforced plastics.
Reinforced concrete construction.
Hong Kong Polytechnic University -- Dissertations
|xvi, 225 leaves : ill. (some col.) ; 30 cm.
|It is well known that concrete can achieve higher strength and greater ductility when subjected to triaxial compression. In structures, concrete is laterally confined in various ways to enhance its strength and ductility. The most widely used concrete confining method is to use transverse steel reinforcement in reinforced concrete (RC) structural members. More recently, fiber reinforced polymer (FRP) jackets have been widely used to strengthen existing RC columns. FRP, being a high-strength, lightweight and corrosion-resistant material with direction-dependent properties, is more advantageous than steel jackets in column strengthening applications. Despite the extensive existing research on the behavior of FRP-confined concrete columns, there is a significant deficiency in existing work on the behavior of FRP-confined large-scale/full-scale RC columns of square/rectangular sections. To address this deficiency, the present thesis presents an experimental study into the axial compressive behavior of FRP-jacketed full-scale RC columns. The specimens were designed according to existing design guidelines to have realistic features. A total of 18 full-scale RC column specimens (350 mm diameter circular columns, 350 mm × 350 mm square columns, 290 mm × 435 mm and 250 mm × 500 mm rectangular columns), all with a height of 1340 mm, were built and tested under axial compression. The columns (including 1 trial test) had circular, square and rectangular sections, with and without confinement by carbon FRP (CFRP) jackets. The circular columns were reinforced with transverse steel reinforcement of different volumetric ratios and were confined with CFRP jackets of different thicknesses to study the effects of transverse steel reinforcement, FRP confinement and their interaction. For square columns, the effects of the volumetric ratio of transverse steel reinforcement and the FRP jacket thickness are also studied. One additional purpose of the square column tests was to study the effect of the rounded corner radius of the square section. Finally, some rectangular columns were tested to study the influence of the section aspect ratio. The test data are interpreted and compared to theoretical predictions of representative models for FRP-confined RC columns. These comparisons indicate the inadequacy of existing models, particularly in predicting the behavior of large FRP-confined square and rectangular RC columns. That is, the existing models have not properly captured the size effect of these columns.
Zeng, Jun-jie
Behaviour and modelling of large-scale FRP-confined rectangular and curvilinearized rectangular RC columns
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Fiber-reinforced concrete
Columns, Concrete -- Testing
|xxx, 388 pages : color illustrations
Existing studies have demonstrated that fibre reinforced polymer (FRP) jacketing/wrapping is highly effective in retrofitting/strengthening reinforced circular concrete (RC) columns with, but it is much less effective for rectangular RC columns (including square columns as a special case) due to the non-uniform FRP confinement in the latter columns. While FRP confinement effectiveness in rectangular columns can be enhanced by rounding the sharp corners, its benefit is limited, particularly for large RC columns, as the corner radius is limited by the presence of internal steel reinforcement. The behavior of FRP-confined concrete in circular columns has been extensively studied over the last two decades and is now well understood. By contrast, much less is known about the behavior of FRP-confined concrete in rectangular columns. Existing studies on FRP-confined rectangular concrete columns have generally been limited to small-scale specimens subjected to concentric axial compression. A number of issues (e.g., the effects of column size, load eccentricity and column slenderness) concerning the behavior of large FRP-confined rectangular RC columns have not been properly addressed. Against this background, this thesis presents a systematic study, conducted both experimentally and theoretically, for the development of an in-depth understanding of the stress-strain behaviour of FRP-confined concrete in large rectangular RC columns subjected to either concentric loading or eccentric loading. In addition, the thesis is concerned with a novel shape modification method named the section curvilinearization method (or simply the SC method) for large rectangular RC columns, in which the flat sides of a rectangular column are modified into slightly-curved sides before FRP wrapping. The behaviour and modelling of FRP-confined concrete in the resulting curvilinearized rectangular columns under either concentric or eccentric loading are also a main focus of this thesis.
The first objective of the research programme was to investigate the stress-strain behaviour of FRP-confined concrete in large rectangular RC columns under either concentric loading or eccentric loading. Both laboratory testing and theoretical analysis were carried out. Various factors, including the section aspect ratio, strain gradient over the section (i.e., load eccentricity), column slenderness ratio, FRP confinement level, and loading direction, were systematically examined. In addition, the size effect in these columns was investigated through comparisons between the present test results and predictions using existing stress-strain models established based on small-scale columns. The second objective of the research programme was to investigate the stress-strain behaviour of FRP-confined concrete in large curvilinearized rectangular RC columns. Two experimental studies of such columns under concentric loading and eccentric loading were carried out respectively. The effects of edge rise-to-span ratio and corner radius ratio of the curved edges were given particular attention; these two factors had not been properly investigated in the existing studies. The effects of section aspect ratio, load eccentricity, column slenderness ratio, and the column size were also systematically examined. A new design-oriented stress-strain model for FRP-confined concrete in curvilinearized rectangular columns under concentric loading was then proposed based on the test results. The final objective of the research programme was to verify the applicability and accuracy of the design equations in the Chinese Technical Code for Infrastructure Application of FRP Composites for large FRP-confined rectangular RC columns (including curvilinearized columns) using the test results presented in this thesis.
Zhao, Jun-liang
Behaviour and modelling of large-scale hybrid FRP-concrete-steel double-skin tubular beams with shear connectors
|Dept. of Civil and Environmental Engineering
Composite construction -- Testing.
Tubular steel structures.
Concrete-filled Tube.
Hong Kong Polytechnic University -- Dissertations
|xxxii, 329 pages : color illustrations
Hybrid fibre-reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs) are a new form of hybrid members developed at The Hong Kong Polytechnic University (PolyU). A hybrid DSTM consists of an outer tube made of FRP and an inner tube made of steel, with the space between them filled with concrete. The existing studies on hybrid DSTMs have been mainly focused on their use as compression members, with only a very limited number of studies on their use as flexural members [i.e., hybrid double-skin tubular beams (DSTBs)]. The limited existing studies on DSTBs have generally been limited to the testing of small-scale specimens without shear connectors. Against this background, this thesis presents a systematical study, both experimentally and theoretically, aimed at the development of an in-depth understanding of the structural behaviour of large-scale DSTBs with headed stud shear connectors. The research project mainly consisted of two parts: the first part was on the behaviour and modelling of headed stud shear connectors in hybrid DSTBs and the second part was on the behaviour and modelling of large-scale hybrid DSTBs with headed stud shear connectors. In the first part, the behaviour of headed stud shear connectors was investigated experimentally using a modified push-out test set-up. A three-dimensional (3D) finite element (FE) approach using ABAQUS was developed to predict the behaviour of headed stud shear connectors. The main advantage of the proposed FE approach over existing approaches lies in the use of a reliable constitutive model for confined concrete under a general state of multiaxial stresses. The effectiveness and accuracy of the proposed FE approach were demonstrated by comparing its predictions with the test results. A parametric study was then carried out using the verified FE approach to clarify the effects of various parameters on the behaviour of headed stud shear connectors. Based on the parametric study, new equations for the load-slip behaviour of headed stud shear connectors were proposed.
In the second part, four large-scale hybrid DSTBs with headed stud shear connectors under three-point/four-point bending were first tested. Four different cross-sectional configurations, including a DSTB/FRP-reinforced deck unit, were included in the tests. A 3D FE approach with ABAQUS/Explicit was then proposed for the modelling of hybrid DSTBs, in which the relative slips between the concrete and the steel tube were duly considered. The bond mechanisms in hybrid DSTBs were investigated using the FE approach to clarify the effects of key parameters. The FE approach was shown to be able to accurately predict both the global load-deflection response and the local relative slips between steel and concrete in hybrid DSTBs. In addition, a force-based fibre-section beam/column element model, which is capable of accounting for the relative slips between the concrete and the steel tube, was developed to model hybrid DSTBs. The accuracy of the beam/column element model was demonstrated to be comparable to that of the 3D FE approach but the former is much more computationally efficient than the latter.
Leung, Lai Ming Gordon
Behaviour of typical pavement subgrade materials in Hong Kong under portable falling weight deflectometer test
|Dept. of Civil and Environmental Engineering
Pavements -- Subgrades
Pavements -- China -- Hong Kong -- Testing.
Hong Kong Polytechnic University -- Dissertations
|228 pages : illustrations ; 30 cm
The major objectives of this research were to improve the understanding of behavior of local pavement subgrade materials under portable falling weight deflectometer (PFWD) test, as well as to make possible recommendations on the utilization of the equipment for mechanistic pavement analysis and design in Hong Kong. In order to fulfill the objectives, investigation works as listed below were accomplished in four key stages: *Resilient behaviour and modulus (MR) of the typical subgrade materials, *Dynamic stresses induced by traffic under typical road pavements, *Stress distributions within the soil mass resulted from the PFWD tests, *Representativeness of LWD moduli (ELWD) to reflect the true properties of the subgrade materials. *Influences of confining pressures to the stress / strain responses and LWD moduli (ELWD) of the subgrade materials, *Correlations between ELWD and MR under the context of Hong Kong. Initial Stage: Resilient behavior of most unbound subgrade materials greatly relies on the surrounding conditions such as stress levels, stress durations, confining pressures and deviator stresses. To facilitate systematic study on these factors and catching up with the trend of many overseas practices, extensive repeated triaxial load (RTL) tests were carried out on a variety of local subgrade materials to study their resilient behaviour. Resilient moduli (MR) of the typical subgrade materials in Hong Kong were obtained and the results were compared with the ones pursued from the PFWD tests at the Final Stage of Study. On the other hand, in order to compare and relate the dynamic stresses induced by ordinary PFWD tests and the ones induced by running traffic under typical road pavements, soil pressure gauges were installed under a widening section of Tolo Highway and the dynamic stresses generated were collected by tailor-designed data acquisition system. Stage Two: Stage Two Study was conducted to gain understanding on the dynamic stress distributions within soil subgrade material placed inside a mass container under LWD tests, with the support by in-situ soil pressure gauges and comprehensive data acquisition system. From the investigation, several important findings were yielded: (1) It was indicated that beyond the distance of 1D (i.e. one times the load plate diameter) from the source of load, the ELWD stays fairly constant, this corresponds to a vertical stress ratio (stress measured by SPG / stress applied by LWD) of about 0.2, (2) The horizontal confining stresses are highest at the location of the source of load and reduce dramatically (in a power form) away from the source, (3) The drop height of mass was found to impose a moderate influence on the ELWD. The increase in drop height of mass can induce increases in confining stresses, and in turn increases in ELWD as clearly indicated by the test results, (4) The horizontal confining pressure has the strongest linear correlation with ELWD, being followed by vertical stress and deviator stress. The test findings were compared and verified by finite element analysis and results between them were found to be reasonably alike.
Stage Three: The purposes of the Stage Three Study were to validate the representativeness of ELWD to reflect the true elastic properties of the typical subgrade materials and to investigate how the surrounding confining pressures induced may affect the strains and subsequent stiffness of a soil column sample. In order to achieve the objectives, the LWD test set-up was modified to mimic the one similar to the set-up of RTL test. The key findings of the Stage Two Study are such as (1) the ELWD produced reflect well on the actual elastic moduli of the subgrade materials, (2) the level of surcharge applied was a significant factor to dictate the magnitude of static confining pressures. In turn, the static confining pressures significantly influenced the dynamic confining pressure magnitudes generated by the LWD tests, (3) the moisture content of the soil was one of the factors that could affect the magnitudes of the dynamic confining pressures, and lastly (4) obvious tendencies of reductions in recoverable strains due to increases in average confining pressures and hence increases in stiffness for the subgrade soils. Final Stage: Correlations between LWD and resilient moduli were investigated under the Stage Four Study (Final Stage). The results justified that the LWD was a useful tool and the LWD modulus was able to form a good yardstick to estimate resilient modulus, which was an essential parameter for mechanistic pavement design. It was found that moduli ratios (ELWD / MR) ranged between 0.74 and 2.36. Softer soil materials tended to have higher moduli ratios (more than 1.0) and stiffer soils have lower moduli ratio (less than 1.0). Through the regression analysis, it was considered that the moduli produced by LWD tests with 50% and 25% of the drop heights were most suitable to form estimations for the resilient moduli of the subgrade materials. Finally two correlation models were established and recommendations were also made for the better utilization of the LWD equipment. The works as covered in the Initial Stage was the first time ever conducted in Hong Kong and the works as contained under the subsequent three stages (Stage 2, Stage 3 and Final Stage) were considered to be highly "original" in a global context.
Gao, Yuan
The characterization and source identification of airborne particles in Hong Kong
|Dept. of Civil and Environmental Engineering
Air -- Pollution -- China -- Hong Kong.
Particles -- Environmental aspects.
Hong Kong Polytechnic University -- Dissertations
|xvii, 201 pages : color illustrations
Low visual range indicates an air pollution problem. In Hong Kong, poor visibility has been of increasing concern since 2000. This thesis explores the relationships between local air pollution and visibility degradation by characterizing particle optical and chemical properties, estimating chemical contributions to light extinction, and identifying particulate matter sources. Particle light scattering and absorption coefficients (Bsp, Bap) in Hong Kong differ among urban, sub-urban and rural areas. Highest values were observed in urban areas due to particles from traffic and cooking sources in addition to regionally distributed particles. Regional-scale Bsp and Bap measured outside the urbanized area was dominantly affected by secondary sulfate, nitrate and organics. The highest PM₁₀ concentrations were observed during the fall and the lowest were found during the spring at three sampling sites. Urban particulate matters (PM) contained large increments of organic and elemental carbon (EC), typical of engine exhaust. Dominant species in the urban area were particle organic matters (POM) and EC, which due to high traffic flow. Regional transportation and stagnant meteorological conditions elevated aged and secondary pollutants in the Hong Kong sub-urban area.
Most of the SO₄²⁻, NH₄⁺, K⁺, OC and EC, were in the size range of 0.56 m to 1.8 m, NO₃⁻, and Cl⁻, were dominated in the 1.8 m to 10 m size range. Because of complex chemical compositions in droplet mode, eight emission sources profiles have been determined in the mode. The largest contributio of droplet mode source was from anthropogenic emission sources, i.e. secondary SO₄²⁻ (24%), industrial emission (19%), vehicle emission, secondary NO₃⁻ and sea salt (13-15% in each) with 10% of other sources. Relatively simple sources were identified in the coarse mode (3 sources) and the condensation mode (4 sources). Over 80% of PMcoarse mass comprised of sea salt and soil dust. Most of the primary emissions were identified in the condensation mode, including 27% vehicle emissions and 18-19% each from residual oil combustion and coal/biomass burning. Secondary formation i.e. secondary SO₄²⁻ contributed approximately 37% of the particles in the condensation mode The special chemical composition and particles size distribution in Hong Kong was observed, mass scattering efficiency of Hong Kong need to be determined. The Hong Kong mass scattering efficiency (MSE) value was investigated under the clean and polluted air quality situation. It is presented as follows: 2.6 (clean) and 3.2 m²/g (polluted) for ammonium sulfate, 2.2 (clean) and 1.5 m²/g (polluted) for ammonium nitrate, 2.1 (clean) and 4.3 m²/g (polluted) for particle organic matters, 1.5 m²/g for sea salt and 1.5 m²/g for soil dust. In general, the largest contributors to particle light extinction in Hong Kong were traffic/engine emission and secondary formation. In other words, to improve visibility degradation situation in HK, the government should control the local traffic emission and build the collaboration with regional institution or government to improve regional air quality. In addition, the air pollution in Hong Kong was mainly affected by south and south east China during autumn and winter months and by north and central China during spring and summer months.
Zhan, Baojian
CO₂ curing of concrete blocks containing recycled aggregate
|Dept. of Civil and Environmental Engineering
Concrete -- Recycling.
Aggregates (Building materials) -- Recycling.
Hong Kong Polytechnic University -- Dissertations
|xxii, 208 pages : color illustrations
For the purpose of environmental protection and reduction in resource consumption, construction & demolition (C&D) wastes have long been recycled and treated as a secondary aggregate for production of new construction materials. However, due to the intrinsically poor quality caused by the attached old cement mortar, recycled aggregates have been reported to weaken not only the mechanical properties, but also the durability of the resulting concrete products. Huge research effort is continuously required to develop innovative techniques to enhance the properties of recycled aggregate and related concrete products. Meanwhile, the calcium silicates phases in cement have been reported to react with carbon dioxide (CO₂) and water, leading to a rapid strength development for cement-based materials. At the same time, a certain amount of CO₂ can be sequestrated into the cement-based materials. Thus, in this research, experimental investigations are performed in order to study the beneficial use of CO₂ curing for producing concrete blocks prepared with recycled aggregates. The work conducted in this research program was consisted of three main phases. The work in Phase I was to explore the feasibility of using the CO₂ curing technique for the production of concrete blocks containing recycled aggregates. Recycled fine aggregates collected from a local recycling plant was used to replace the natural fine aggregate in concrete blocks. The CO₂ curing process was performed with a duration of 6 h, 12 h and 24 h, under the pressure of +0.1 bar. The experimental results proved that CO₂ curing process rendered the concrete blocks prepared with recycled aggregates with higher compressive strength and lower drying shrinkage than the corresponding moist cured blocks. However, curing time and amount of recycled aggregate present in the blocks had insignificant effects on the strength gain and CO₂ curing degree.
The study in Phase II, mainly focused on evaluating several important factors that might influence the CO₂ curing process of concrete blocks made with recycled aggregates. There were two parts including materials characteristic and curing regime. In part 1, the effects of materials characteristics of the concrete block on CO₂ curing process were investigated, including moisture content, bulk density, aggregate to cement ratio, recycled aggregate content and types of binders. The results showed that, the initial moisture content and the aggregate to cement ratio in the concrete blocks significantly affected the CO2 curing degree and compressive strength of the concrete blocks. The bulk density and the recycled aggregate content also influenced the CO₂ curing process, but their effects on compressive strength were more complex. The work in this part further confirmed that the inclusion of recycled aggregates can improve the CO₂ curing efficiency. In part 2, the influence of several factors associated with the curing conditions on the curing degree and compressive strength of the concrete blocks were investigated, including curing time, temperature, relative humidity, pressure and post water curing after the pressurized CO₂ curing (PCC) method was employed. An experiment with flow-through CO₂ curing (FCC) method was also carried out. The results of PCC experiments showed that high percentage of the total considerable curing degree and compressive strength were attained during the first 2 hours of CO₂ curing period, and extending the curing time yielded slower gain of curing degree and compressive strength; the variation of temperature from 20 ℃ to 80 ℃ and relative humidity from 50% to 80% had limited effects on PCC; the effects of CO₂ gas pressure on the curing degree and compressive strength were the most pronounced between 0.1 bar and 0.5 bar within the first 2 hours of PCC; the post water curing allowed the concrete blocks to attain further strength gain. The results also indicated that, a lower curing degree and slower strength development at the early age were observed for the FCC-cured concrete blocks; however, after 24 hours of curing duration, they were comparable to those obtained from the PCC method. In Phase III, the intrinsic mechanism for rapid strength development of the CO₂-cured cement-based materials was studied, and the chemical and microstructural evolution of cement paste subjected to coupled CO₂- water curing was investigated. These was achieved through identifying the phase variations, change in porosity and morphological evolution of the structure of CSH gel. The results indicated that more than 2 hrs of CO₂ curing might lead to a lower long term strength development after the subsequent hydration period. The results of the solid state ²⁹Si MAS NMR showed that the CO₂ curing process can remove calcium ions from the interlayer of CSH, and promote the merging of dimers into polymers; and thus the formed CSH had a longer silicate chain length and a higher degree of polymerization. This is regarded as the main reason for the rapid strength development of the cement paste at the early age when subjected to the CO₂ curing process.
Liao, Weiyang
Comfort assessment of tower-like slender structures under typhoons and earthquakes
|Dept. of Civil and Environmental Engineering
Tall buildings -- Earthquake effects.
Tall buildings -- Vibration.
Hong Kong Polytechnic University -- Dissertations
|xxviii, 289 leaves : ill. ; 30 cm.
Recently there has been an increasing demand for high-rise buildings and skyscrapers in urban areas all around the world. Due to their large scale and impressive height, flexible high-rise structures experience discomfort for the inhabitants in terms of excessive perceived motion caused by strong winds and earthquakes. Design of tall buildings should meet the serviceability criteria such that the wind and earthquake induced motions of a tall building within an acceptable range for occupant comfort, which may govern the design. Practices in this topic are usually based on the design wind and earthquake parameters according to historical experiences. Field measurement data of real structures, especially those of several hundred meters high, are very rare. Field monitoring of dynamic responses of a high-rise structure during typhoons and earthquakes provides a unique approach to verifying the parameters and assumptions adopted in design of the structure and to validating the wind tunnel or shaking table testing results. Particularly, a sophisticated structural health monitoring (SHM) system consisting of over 800 sensors has been implemented on the Canton Tower of 600 m high for both in-construction and in-service real-time monitoring. In the past three years, the Canton Tower has experienced several typhoons and earthquakes, during which both static and dynamic responses have been successfully collected through the SHM system. Taking the Canton Tower as the test bed, the research presented in this thesis is devoted to the investigation of comfort assessment of high-rise structures under typhoons and earthquakes. This PhD study has developed a vibration comfort assessment framework by considering various factors such as section type, torsion effect, whole structure response, and uncertainties. First, methodologies in signal processing for vibration comfort assessment are discussed. The torsion effect has been taken into consideration because of the asymmetry of the structure. Second, assessment of the comfort of top floor of the main tower and the contour map of serviceability are developed accounting for the torsion effect. Third, a procedure for assessing average comfort of the whole structure has been proposed by considering the structural profile and dynamic characteristics of the structure. Finally, a probability based reliability evaluation method of vibration comfort with the use of field monitoring responses is developed.
The framework is then applied to the comfort assessment of the Canton Tower using the monitoring data acquired during four typhoons. The wind properties such as mean wind and speed, turbulence and integral scale, gust factor and wind spectra, are first obtained. The acceleration responses at different levels under typhoons have also been investigated. The vibration comfort assessment considering the wind properties and spatial distribution of sensors has been conducted. A regression model is obtained to account for the torsion effect and wind properties. The real probability distribution of acceleration peak values has been obtained and compared with that used in the design. In this study, the principle of equivalent normalization is introduced to evaluate the reliability index because both the monitoring-obtained distribution and the distribution assumed in design do not obey the normal distribution. In a similar manner, the vibration comfort assessment framework is employed to assess the comfort of the Canton Tower under earthquakes. The vibration acceleration responses at each monitoring level under earthquakes are first investigated and discussed, in terms of depth, magnitude, and distance of the earthquakes. The acceleration responses are then used to assess the comfort of the top floor and the structure as a whole. In this context, the comfort index for the whole structure is developed according to the earthquake parameters. The corresponding regression model is also derived. In consideration of the uncertainties in both structure responses and criteria used in this assessment framework, a probability based comfort assessment method for the top floor is proposed in which the distributions of peak values under earthquakes are addressed. In summary, the research addressed in this thesis mainly contributes to the development of a vibration serviceability assessment framework for high-rise structures under typhoons and earthquakes using the field monitoring data. This study also benefits the design assumption verification and the improvement of design parameters for future high-rise structures.
Yu, Han
Comparison of environmental performance of steel and reinforced concrete buildings by linear and nonlinear analysis
|Dept. of Civil and Environmental Engineering
Hong Kong Polytechnic University -- Dissertations
Building, Iron and steel -- Environmental aspects
Buildings, Reinforced concrete -- Environmental aspects
|xxxii, 310 pages : color illustrations
There has never been a better time to save energy, but every start would be smart. Buildings play a remarkable role in human civilization, however, at the same time, are responsible for the largest energy consumption and Green House Gas emissions around the globe. Due to the alarmingly increased concern raised towards the environmental sustainability, engineering design trends change mildly during the past few decades and efforts have never been enough towards the realization of real energy-efficiency improvement. The energy efficiency of municipal landmarks, residential buildings and commercial high-rises has increasingly been improved in different ways and fields to combat the battle towards energy sustainability, supply security and economic competitiveness. Many countries and cities, including Hong Kong, have launched policies or actions to control and reduce the embodied energy and emissions of buildings by the application of low-carbon construction materials. In view of this, the Construction Industry Council has launched a Carbon Labelling Scheme for Construction Products for industry players to select 'low carbon'materials'. On top of that, alternative structural design might further reduce the embodied carbon at a building system level. In addition to the essential requirements on quality and safety of a building, embodied carbon can be integrated in the structural optimisation process to generate low carbon construction design. Nonlinear analysis method has showed its advantages in many areas along its developing history. As its application has been more and more popularly recognized and suggested by officially published design codes, the advantage of nonlinear analysis in terms of environmental performance enhancement would be worth of further exploration.
This thesis serves as a fulfilment of the final assessment of the PhD research study, aiming at addressing this environmental advantage that nonlinear analysis would be able to bring to the field of structural design, due to its capability to optimise the use of building materials in construction without over-designing redundant members and under-designing critical members. Based on this technique, the environmental impact of using steel, composite and reinforced concrete structures will be evaluated in a scientific manner. The importance of environmental performance would be addressed firstly followed by an overview of the background and literature preparation for the basis formation for the comparison study to be carried out. Structural models in both steel and reinforced concrete would be established tobe analysed and designed through both conventional linear method and nonlinear method. Typical building design cases fulfilling Hong Kong design background and requirements have been analysed and demonstrated. Results have been collated through the quantification and mitigation of total embodied carbon (EC) in a system level for all steel, reinforced concrete (RC) design buildings and even with composite floor system at different heights, with or without underground consideration, through the scientific integration of low carbon materials and Nonlinear Structural optimisation. An environmental advantage target is to be achieved through the comparison in terms of material consumption, embodied energy and embodied carbon, followed by a potential economic aspect, nonlinear analysis would be able to bring to the field of structural design. Low carbon building design options interms of different design purpose or materials will be provided for the future reference of developers and engineers.
Lin, Shiying
Compound modification of asphalt mixtures for low-noise, low-emission and durability purposes
|Dept. of Civil and Environmental Engineering
Pavements, Asphalt -- Materials -- Additives.
Pavements, Asphalt -- Testing.
Hong Kong Polytechnic University -- Dissertations
|x, 84 pages : color illustrations
|Asphalt pavements are constructed widely all over the world because of various advantages, such as superior engineering performance, comfortable riding surface, the short maintenance time, to some extent, and alleviate the traffic noise. The utilization of different asphalt pavement has different strength, however, also has its limitations. High temperature needed when producing and constructing asphalt layers generates fumes and odors. Such emissions not only pollute the environment, but also pose health risks to the workers. In addition, the increasing volume of vehicular traffic on the roads also aggravates concerns of road pavement noise. Modifiers are introduced into the asphalt mixture to help make the asphalt a better performance in optimizing the air emissions, low-noise, and the durability properties. This study aims to assess different modified asphalt mixtures with focus particularly on the mechanical properties, acoustical emissions, and air pollutant emissions. Within the constraints of available equipment in the laboratory and construction sites for different pavement surfaces, limited but well-designed laboratory tests and site monitoring works were conducted. This study shows that the addition of modifiers, such as polymer and crumb rubber, can help improve the mechanical quality and low noise performances of the pavement but need higher working temperatures, which severely exaggerates the fume and odor issues as well as the concern of health. The warm mix additives, such as Sasobit®, mixed with the asphalt mixture can lower the working temperatures and thus reduce the air and odor emissions. The Gap-graded asphalt pavement with a smaller aggregate size has performed well in the mechanical and low-noise performances. With the modification by the Sasobit®, its particulate matters and volatile organic compound pollutants can be significantly reduced.
Now showing items 1-20 of 118Next Page


text:
This is the official No Life 'Til Metal & Metal Metropolis discussion board.
metal, thrash, heavy, speed, ultimatum, hirax, avenger, blood
Free forum : A Supernatural Roleplay located in the heart of a bustling modern city where the members drive the site's plot. Join our different factions and engage in threads that will give your characters fame one way or another.
fantasy, supernatural, roleplay, modern, mature, dice, roller
The Ebon Circle is a Feral Heart based Roleplay and Social Group about the Kreptis species
ebon, circle, feral, #heart, based, roleplay, social, group, about, kreptis, species
Play By Post Forum For Second Edition Changeling: The Lost
hedgebound, #heart, play, post, changeling, lost, second, edition, chronicles, darkness
Khaled Mohammed saed Tayeb
A Dragonball RPG that lets any style of roleplay welcome!
free, dragonball, never, ending, saga, forumotion, reation, based, that, goes, along, plot, role, play, your, #heart, out!
Heart of Soul forums - 'Where a Heart of Soul coincide'
Hi hi hi hi hi hi.
#heart, farts
free forum : High School roleplay. Sacred Heart High School
*~Do not go where the path may lead. Go, instead, where there is no path and leave a trail. ~*
Free forum : A Roleplay center for all of you Hetalia fans! Come in, pick a country, and enjoy Rping to your heart's content.
free, forum, hetalia, roleplay, center, role, play, axis, powers, hetalia:
A place for all fans of 가물치(K-much) to meet and have fun together. Let's spread the heart shaped things all over the globe!
k-much, kmuch, kamulchi, 가물치, crayon, chrome, loki, bornus, g.low, honggyu, moobin, younggyun, jaeoh, sunghyun, snakehead
Free forum : Friendship, Games, Fun, Laughter
brenda's, #heart, gold#2, friendship, community, friends, computers, laugher, games, information, crafts, news, pets, recipes
Free forum : Website of the Clan The Ebon Circle, the Kreptis Species.
free, forum, ebon, circle, website, clan, kreptis, species, feral, #heart
This is the forum of Heart Chorus, a chorus on YT that covers Vocaloid and Anime OP songs in English AND Japanese.
#heart, chorus, this, forum, that, covers, vocaloid, anime, songs, english, japanese
Free forum : Adopt a dragon!
free, forum, dragon-heart, adopt, dragon, forumotion, lair, trainer, rider, dragons, elements, battles, quests, shop, draconia, humans, awesome
Luminesce is a guild of excellence and to obtain excellence we must work together as an assemblage. We're here to enjoy ourselves and we want you to enjoy yourself as well and what better way then to find a group that you can bond with. We hope that
lucent, #heart, luminesce, guild, gamania, beanfun, distance
A Pokémon forum!. Arena. pokemon arena pokemon arena forum chat nintendo seidou pokemon seidou
#heart, gold, soul, silver, heartgold, soulsilver, pokemon, arena, nintendo, pokémon, pokemonarena, pokémonarena
School of Excellence. Home of Elegance. Heart of Ethics
bnchs, official, forum, site, comprehensive, compre, school, excellence, home, elegance, #heart, ethics
Three families at war with one another in a modern fantasy AU Universe.
#heart, three, families, with, another, modern, fantasy, universe
This is the forum website for the Ookami Pack in Feral Heart.
Balisong forum 4 young and young at heart.
Health care
health, care, nutrition, news, insurance, vitamins, colds, fever, mental, exercise, dieting, men's, women's, children's, cancer, #heart, systems, organs, bones
Welcome to LuvROSE, The Heart Of ROSE Online. Here is our forum where you can discuss issues or problems and sovle them. Enjoy!
free, forum, luvrose, ultamite, rose, experience, join, today!!
Free forum : Heart of the Akatsukis Chaos. Only true meisters can enter
free, shadow, realm, #heart, akatsukis, chaos, only, true, meisters, enter
Come on in and rest your weary heart. For all anime lover's are welcome here....
I am a Darwinian Excellence is my goal Universe is my home. Finder of my true Self, Civilized, humanize Lover of Human Life. Darwinian, Yes I am!, In my heart In my soul, Darwinian Forever!
darwin, international, school, ateneo, student, that, love, learn, give, their, best, just, achieve, care, computer, friends, money, teachers, teach

subset: commoncrawl