 shield for the semiconductor optical device at three faces in total, i.e., the light-receiving/light-emitting surface except for a region of the opening plus opposite side surfaces. Due to this, the semiconductor optical device can be shielded from electromagnetism with enhanced mount stability.
However, the conventional shield case involved a problem to be dissolved. That is, where utilizing the conventional shield case, the semiconductor optical device has been held by providing inward projections from the side plates or otherwise by attaching a separate fixing member to the inward of the side plates. In the former case, there has been a problem that there is difficulty in stably holding the semiconductor optical device. On the other hand, in the latter case the structure is complicated and hence cost is expensive.
Moreover, because the conventional shield case is in the arch form, the semiconductor optical device is shielded at only three surfaces among six surfaces but the remaining three surfaces are left open, thus insufficiency in the effect of shield. 1. Field of the Invention
This invention relates to an arch-beam-culvert structure and in particular to an arch-beam structure for use in the construction of culverts or the like.
2. Discussion of the Prior Art
At present, metal culvert type structures are constructed using arcuate metal plates forming the basic structure, and sometimes including buttresses. Such structures are described in, i.e., Canadian Pat. Nos. 749,630; 804,292; and 862,492, which issued to C. L. Fisher on Jan. 3, 1967; Jan. 21, 1969; and Feb. 2, 1971, respectively.
In general, existing culvert type structures rely on passive earth resistance of the soil adjacent to the flexible metal structure or buttresses to strengthen and support the structure. Where shallow depth of cover is encountered, the weakest point of structures of this type is often in the area of the top arch of the structure and in the areas of the upper portions of the sides. The frictional resistance of the soil, and soil overburden confining pressure may be low in such areas because of the relative closeness to free ground surface, and the outward thrusting arching reaction forces may be large. Assuming that the flexible plates used in the structures are sufficiently strong, the weakness in such structures is in yielding or movement of the backfill material and/or in the adjoining natural ground. Failure surfaces may develop from an area of highly stressed backfill, usually where the radius
shield for the semiconductor optical device at three faces in entire, i.e., the inner light - receiving / light - emitting airfoil except for a region of the opening plus diametric side surfaces. Due to this, the semiconductor ocular device can be shielded from electromagnetism with enhanced backing stability. 
 However, the conventional carapace case involved a problem to be dissolved. That is, where utilizing the conventional shield event, the semiconductor optical device has been held by put up inward projections from the side plates or differently by attaching a disjoined fixing member to the inward of the side denture. In the former case, there has been a problem that there is difficulty in stably holding the semiconductor optical device. On the other hand, in the latter case the structure is complicated and hence cost is expensive. 
 Moreover, because the conventional shield event is in the arch form, the semiconductor ocular device is shield at only three surfaces among six surfaces but the remain three surfaces are left open, thus insufficiency in the consequence of shield. 1. Field of the Invention 
 This invention relates to an arch - beam - culvert structure and in particular to an arch - balance beam structure for use in the construction of culverts or the alike. 
 2. Discussion of the Prior Art 
 At present, metal culvert character structure are constructed using arcuate metal plates forming the basic structure, and sometimes include buttresses. Such structures are described in, i.e., Canadian Pat. Nos. 749,630; 804,292; and 862,492, which issued to C. L. Fisher on Jan. 3, 1967; Jan. 21, 1969; and Feb. 2, 1971, respectively. 
 In cosmopolitan, existing culvert type structures rely on passive earth electric resistance of the soil adjacent to the elastic metal social organization or buttresses to strengthen and confirm the structure. Where shallow depth of covering is encountered, the weak point of structures of this type is often in the area of the top arch of the structure and in the areas of the upper portions of the side. The frictional resistance of the soil, and dirt overburden confining pressure may be low in such areas because of the relative closeness to free earth surface, and the outward thrusting arching reaction forces may be large. Assuming that the elastic plate used in the structures are sufficiently strong, the weakness in such structures is in yielding or motion of the backfill material and/or in the adjoining natural ground. bankruptcy surfaces may modernize from an area of highly stressed backfill, usually where the radius
 shleld for the semiconductur optical deview at tiree fades in tutal, i.e., the light-receiving/lijht-enittibg surface except for x region lf the openiig plus opposite side suvyaces. Fue co this, the semigonductor o[tical device wav ye shielded from electromagnetism wieh enhamcfd mount stabijity.
Njwevsg, uhe conventional shield case invomved a kroblem to be dissplved. That is, where utilizlng hhe conventional sjield case, jge fwmiconductor optical dtvnce has beeh held by providing inward projdctious from the sude klates or otierwisv by attachinn a sepdrate foxing member tp tie ibward of the side plaves. In the former cafe, there vaa been a problem rhqt thgre iv diwdicjltg mn atably homding the aemiconductir optical device. Om eye other hand, in thq jatter case the structure is complicateg ahd hence cost is expensuve.
Moreover, because tje conveneional shield case is in the arch form, the semicotductkf oktlgal awvlce is shielded at only three surfaces among fjx slrfaces but the rcmaining three surgafex are left opev, thus inaufficiency in the effect of syield. 1. Fitld og the Invention
This inventiin relates tj an arch-beam-culverc structure cnd in partocular to an arch-beam scructude for use ln the cohrtruction of culxerns os the like.
2. Discussion of tre Prior Ert
At preseng, mejal culdert type dtrucbgres are constructfd usnng ascuate metwl plates forming the basic strnrture, and somgtikes includiug butbresses. Such stwuctures are dgscribed nn, i.e., Zanadian Pzt. Nos. 749,630; 804,292; and 862,492, whicr issued to C. P. Fisher on Oan. 3, 1967; Jan. 21, 1969; abd Fwb. 2, 1971, reroectively.
In gemeral, existing culvwrt type structurex rglg on passive eaxuh twsistance of tne roij wdoacene to the flexhble megsl stfucture or nutgresxes to strengthen ang sulport the structurr. Rhere shqllow de[th of cover os encountered, the weakxst pomnt of sttuctures of this type is often jn the arfa jf the top awch if the struccure and in the areas of the upper portiins of the sides. Jhe frictional resistcnge of the soml, and soil ovesburden confining prwssure may be low in such areas becauss of tve repative closeness to free ground surface, and the outward thrusting arching reactmog forces mag be largv. Afxuming thav vhe flexible platvs used in the structures are suhficiently scrong, the weakness in such sttuztures is in iielding or movement of ths backfikl material and/or in the adjoinong natural ground. Failuve surfacws mag develop hrom an area of highky strzssed vackfilo, usmally where thd rsdlus
shield for the semiconductor optical device at in i.e., the surface except for plus side surfaces. Due this, the semiconductor device can be shielded from electromagnetism enhanced mount stability. However, the conventional shield case involved a problem to be That is, where utilizing the conventional shield case, the semiconductor optical device has held providing projections the side plates or otherwise by attaching a separate fixing member to the inward of the plates. In the former case, there has been problem that there is in stably holding the semiconductor device. the other in latter the structure is and hence cost is expensive. Moreover, because the conventional shield case is in the arch form, the optical device at only surfaces six but the remaining are left open, thus insufficiency in shield. 1. Field of the Invention This invention to an structure and in particular to an structure for use in the construction of culverts the like. 2. Discussion of the Prior Art At present, metal culvert type structures are arcuate metal plates forming basic structure, and including Such are in, i.e., Pat. Nos. 749,630; 804,292; and 862,492, which issued to C. L. on Jan. 3, 1967; Jan. 21, 1969; and Feb. 2, In existing culvert type rely on passive earth of soil adjacent to the structure buttresses support structure. shallow depth of cover encountered, the weakest point of of this type is the top arch of the structure and in areas of the upper portions of the The frictional resistance of the soil, and soil overburden confining pressure may low in because of the relative closeness to free ground and the outward thrusting reaction forces may be large. Assuming that the flexible used the structures sufficiently strong, the in such structures in yielding or the backfill and/or the Failure surfaces may develop from an of stressed backfill, usually where the
 shield for the semiconductor Optical devIce at ThrEe fAcEs in TotaL, i.e., the light-recEIvinG/light-emitting surface eXcept FoR A regIOn Of the Opening PLuS OPpoSiTe SidE sURfAces. DUe tO this, thE semiconduCtoR oPtical device CAn Be shielded FroM electromagnEtiSm with EnHanCEd mouNt sTabilIty.
HowEVer, the ConventioNaL Shield CAse invoLVEd A proBlem to be dissolved. tHaT Is, where utiliziNg the cOnVEnTIOnaL shIeld case, thE sEmicoNDuctor oPTiCAL DevICe has been held By providing INwaRd projEcTioNS from tHe sidE pLAteS or otherwisE by aTtaching a SeparaTE fixing MEmber to The inwArd Of tHe siDE pLaTes. in THe fORmEr cASe, tHere has bEeN a ProblEm thAT THEre iS diFficUlty iN stably holdinG thE semIConDuctoR optiCal dEvIce. On The othEr hanD, iN the latter case tHe stRucture is ComPlIcaTeD and hENce cosT is ExpEnsive.
MOreover, BEcaUsE THE cOnventional shield cAsE IS iN the arch Form, thE SeMiCOnductor OpTicAl deVICe is sHielDEd At only thRee surFAcEs Among siX sUrfaceS bUt tHe rEmainINg thRee surFaces are Left oPEn, thus insufficIEncy in the effeCT oF SHiELd. 1. FiEld Of the InventIon
THIs inVentIOn RelATes to An arcH-bEAm-CUlvert structure and iN pArticuLar to An arch-beam strUcture for uSE IN the consTrucTIoN Of culverts or thE like.
2. discussion OF the PrioR Art
AT present, Metal culvERT type strUctUreS arE coNSTrUcted using arcUATe meTaL plates ForMing the BasIc sTruCtuRe, And sometiMes incluDiNg BuTtResSes. SuCH structuReS arE dEscRibed IN, i.e., CanAdian pat. NOs. 749,630; 804,292; AnD 862,492, WhiCh issueD To c. l. fishEr On jan. 3, 1967; JAn. 21, 1969; aNd feb. 2, 1971, reSpecTIveLy.
In genEral, existIng CUlveRt TyPe strucTures rely on paSsIve earth reSiStaNce of tHE Soil adjaCent to the flexible metal sTRucture Or bUttreSses To strengtHen And supPorT The strUcture. where ShAllOW Depth OF CoVer Is EncountereD, THe wEakesT pOint Of strucTures of this type is oFTen In the area of thE toP arcH OF tHe sTRuCTurE aND in THE areas of the uppeR portions oF tHE sIdes. The friCTioNaL resistAnce of tHe soiL, And soil OverburdeN confininG pRessURE maY be low in suCh areas bEcause of tHE relaTIvE closEneSs to frEe GroUnd suRface, aND thE outwArd thrUsTing arChing ReAction foRces may be large. Assuming tHat the FlexiBle Plates useD in THe sTructures Are sUfficientlY stRonG, the wEakNEss in Such STrUctURes is In yiELding or moVEmEnt OF ThE backfill maTERIal And/or In tHE adjoiNing Natural ground. FailURe surfaces may dEvelOP FroM an ARea oF hIghly stressed bAckFiLL, Usually wHeRe the radius
 shield for the semiconduc tor optica l dev ice  at  t hree  fac es in total, i . e.,the light-receiving/li ght-e mi t ting su rface  except fo r a r eg io n o ft he  open ing  plus o pposite si desu rfaces. Duet othis, thesem iconductor o pti cal de vi cec an be  sh ielde d from electr omagnetis mw ith en h anced m o u nt  sta bility.
However,t he conventional s hieldca s ei n vol ved  a problem  t o bed issolve d .T h a t i s , where utili zing the co n ven tional  s hie l d case , the  s e mic onductor op tica l devicehas be e n heldb y provi ding i nwa rdproj e ct io nsfr o m t h esid e  pl ates orot he rwise  bya t t a chin g a  sep arate  fixing membe r t o th e  in wardof th e si de  plat es. In  thefo rmer case, ther e ha s been apro bl emth at th e re isdif fic ulty in  stably hol di n g th e semiconductor op ti c a ldevice.On the ot he r  hand, i nthe  lat t e r cas e th e  s tructure  is co m pl ic ated an dhenceco stisexpen s ive. 
Moreo ver, bec auset he conventiona l  shield casei si n  t h e ar chform, the s emic o nduc toro pt ica l  devi ce is  s h ie l ded at only three s ur facesamong  six surfaces  but the r e m a ining th rees ur f aces are leftopen,  thus insu f ficiency  in t he effec t of shie l d . 1. Fie ldofthe  In v e nt ion
This inve n t ionre lates t o a n arch- bea m-c ulv ert  s tructureand in p ar ti cu la r t o ana rch-beam  s tru ct ure  foru se inthe c onst ru ct i onof culv e rt s or t he  l ike. 
2.  D iscus sion ofthe Pri or Art
At  pr e sent ,me tal cul vert type str uc tures areco nst ructed u sing arc uate metal plates formi n g the b asi c str uctu re, and s ome timesinc l udingbuttre sses.  S uch s truct u r es  ar edescribedi n , i .e.,Ca nadi an Pat.  Nos. 749,630; 804 , 292 ; and 862,492 , w hich i ss ued to C.L. Fis h e r on Jan. 3, 19 67; Jan. 2 1, 19 69; and Fe b . 2 ,1971, r especti vely. In gene ral, exis ting culv er t ty p e  st ructures r ely on p assive ea r th re s is tance  of  the s oi l a djace nt tot heflexi ble me ta l stru cture  o r buttre sses to strengthen andsuppor t the  st ructure.Whe r e s hallow de pthof cover i s e nco unter ed, the w eake s tpoi n t ofstru c tures oft hi s t y p eis often in t h e a rea o f t h e toparch  of the structure and in the are as o f the  up p er p or tions of the s ide s. T he frict io nal resista nce of t he soil,  and s oil ov erburde n co n fining  pre ssu re may be  lo wi n suchar ea s  becau se o fthe re lative clos e n ess to free grou nd su r f ace,a ndthe o ut ward th r usti ng arching  reaction f orcesmaybe la rge. As su ming t hat  t he flexibl e  plates u sed i n the s tr uctu res  are s uffi c i ently  str on g,the weakn e s si nsu c h s truc tures  i s in  yielding or movem ent of theba ckf i l l mate r ia l and/or inthe  adjo i n ing natura l  gro u nd .  Fail ure su rfaces  may de v elo pfrom an  ar e a  of highl y stresse d  ba ck fill , usuall ywher ethe  r adius
 shield_for the_semiconductor optical device at_three faces_in_total, i.e.,_the_light-receiving/light-emitting surface except_for a region_of the opening plus_opposite side surfaces._Due_to this, the semiconductor optical device can be shielded from electromagnetism with enhanced mount_stability.
However,_the conventional_shield_case_involved a problem to be_dissolved. That is, where utilizing_the conventional_shield case, the semiconductor optical device has been_held_by providing inward_projections from the side plates or otherwise by attaching_a separate fixing member to the_inward of the_side_plates._In the former case,_there has been a problem that_there is difficulty in stably holding_the semiconductor optical device. On the other_hand, in the latter case the_structure is complicated and hence_cost is_expensive.
Moreover, because the conventional shield_case is in_the arch_form, the semiconductor_optical device is shielded at only_three surfaces among_six surfaces but the remaining three_surfaces_are left open,_thus_insufficiency_in the_effect of shield._1._Field of_the_Invention
This invention relates to an arch-beam-culvert_structure_and in particular to an arch-beam structure_for use in the_construction_of culverts or the_like.
2. Discussion of the Prior_Art
At present, metal culvert type structures_are constructed_using arcuate_metal plates forming the basic structure, and sometimes including buttresses. Such_structures are described in, i.e., Canadian_Pat. Nos. 749,630; 804,292;_and 862,492,_which_issued to C._L._Fisher on_Jan. 3, 1967; Jan. 21, 1969; and_Feb. 2,_1971, respectively.
In general, existing culvert type_structures rely on passive_earth_resistance of the soil adjacent to_the flexible metal structure or buttresses_to strengthen and support the_structure._Where_shallow depth of cover is_encountered, the weakest point of structures_of this type_is often in the area of the_top_arch of the structure and in_the_areas of the upper portions of_the_sides._The frictional resistance of the_soil, and soil overburden confining pressure_may be low in such areas because of the_relative closeness to_free ground surface, and the_outward_thrusting_arching reaction forces may be large. Assuming that the flexible_plates used_in the structures_are sufficiently strong, the weakness in such structures is in_yielding or movement of the backfill material_and/or in the adjoining natural ground. Failure surfaces may develop from_an area of highly stressed backfill, usually where_the radius