Gravity and horizontal forces cause the transfer of vertical shear and moments between concrete flat slabs and their supporting columns. These forces can cause punching failure. Design equations for safety against punching given in the Canadian Standards Association and the American Concrete Institute codes are critically reviewed. It is shown that the equations give in some cases incorrect stresses which do not satisfy equilibrium. A modification is suggested which makes the equations applicable to all cases. The paper also discusses the codes' approach of sharing the resistance to transferred moment between resistances by flexure and by eccentricity of shear, using the coefficient γv. Comparisons are made with the result of finite element analyses. It is concluded that the code equations, with the suggested modification, are adequate, provided that appropriate values are used for the coefficient γv. Key words: columns, connections, flat concrete plates, moments, punching shear, reinforced concrete, shea...


Results of researches of various nature nano-objects and tribotechnical researches of the motor oils containing nano-sized particles were examined.Copyright © 2005 by ASME


Abstract : The study was undertaken to see if, in the light of recent drastic price reductions and technology advancements, the use of a programmable general-purpose minicomputer as a versatile Time Division Multiplexer (TDM) now presents a more viable economic alternative to the special purpose hardwired equipment commonly used for this purpose. Methods for software implementation of the required TDM functions were explored, and preliminary hardware and software concepts were set forth. The study concluded that the concept of implementing a minicomputer-based TDM using currently available machines is a feasible one. In addition, cost advantages aside, the flexibility inherent in such an approach appears imminently desirable. (Author)


This paper presents how the response frequencies of dental implant structure depend on material properties of both interfacial tissue and dental structure during the osseointegration. Firstly, artificial bone block models were used to mimic various dental implant structures (with different vertical heights of alveolar bone and cortical thickness) in clinic. The structural resonance frequencies (RFs) were also measured by a noncontact displacement sensor. The obtained results were compared with corresponding finite element analysis (FEA). Secondly, the designated bone tissues around the implant were investigated through numerical simulation and corresponding measured RFs. A human mandible model was constructed based upon a set of in-vivo dental computerized tomography (CT) images. Both the simulation and experimental results show that with larger vise fixation heights the RFs of dental structure with three cortical thickness (1, 2 and 3mm) range from 6771±4.5 to 7078±17.3 Hz in the mesial-distal (MD) direction, and from 5230±6.3 to 6119±18.0 Hz in the buccal-lingual (BL) direction. Therefore, the same approaches can be used to evaluate healing conditions during the osseointegration stages for the other orientations. Additionally, Using the FEA enables to assess the stiffness of interfacial tissues that influence the RFs of implant structure during the primary stability stage; more precisely the RFs increase gradually to a steady level following bone tissues becoming stiffer. The FEA results indicate that using the RF changes can identify the conditions of osseointegration.


This paper proposes a method for designing a feedback controller to yield an oscillation of a prescribed profile as a stable limit cycle of the closed-loop system. The plant is assumed linear, but the controller is necessarily nonlinear to achieve orbital stability of the oscillation. The controller structure is inspired by central pattern generators - neuronal circuits for rhythmic body movements during animal locomotion. Design conditions are obtained for the neuronal interconnection matrix through the method of multivariable harmonic balance. A numerical example demonstrates utility of the design method.