CA1180200A - Composite arch structure - Google Patents
Composite arch structureInfo
- Publication number
- CA1180200A CA1180200A CA000410729A CA410729A CA1180200A CA 1180200 A CA1180200 A CA 1180200A CA 000410729 A CA000410729 A CA 000410729A CA 410729 A CA410729 A CA 410729A CA 1180200 A CA1180200 A CA 1180200A
- Authority
- CA
- Canada
- Prior art keywords
- liner
- arch portion
- top arch
- stiffening
- composite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000002131 composite material Substances 0.000 title claims abstract description 45
- 239000000463 material Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 14
- 239000004567 concrete Substances 0.000 claims description 12
- 238000011065 in-situ storage Methods 0.000 claims description 5
- 239000011150 reinforced concrete Substances 0.000 claims description 5
- 238000005266 casting Methods 0.000 claims 2
- 238000004519 manufacturing process Methods 0.000 abstract 1
- 150000002500 ions Chemical class 0.000 description 11
- 239000002689 soil Substances 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 239000003351 stiffener Substances 0.000 description 3
- NLZUEZXRPGMBCV-UHFFFAOYSA-N Butylhydroxytoluene Chemical compound CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 NLZUEZXRPGMBCV-UHFFFAOYSA-N 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 101150034533 ATIC gene Proteins 0.000 description 1
- XKJMBINCVNINCA-UHFFFAOYSA-N Alfalone Chemical compound CON(C)C(=O)NC1=CC=C(Cl)C(Cl)=C1 XKJMBINCVNINCA-UHFFFAOYSA-N 0.000 description 1
- 241000905957 Channa melasoma Species 0.000 description 1
- 241000272470 Circus Species 0.000 description 1
- VGMFHMLQOYWYHN-UHFFFAOYSA-N Compactin Natural products OCC1OC(OC2C(O)C(O)C(CO)OC2Oc3cc(O)c4C(=O)C(=COc4c3)c5ccc(O)c(O)c5)C(O)C(O)C1O VGMFHMLQOYWYHN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000353097 Molva molva Species 0.000 description 1
- 241000022563 Rema Species 0.000 description 1
- AJLFOPYRIVGYMJ-UHFFFAOYSA-N SJ000287055 Natural products C12C(OC(=O)C(C)CC)CCC=C2C=CC(C)C1CCC1CC(O)CC(=O)O1 AJLFOPYRIVGYMJ-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- AJLFOPYRIVGYMJ-INTXDZFKSA-N mevastatin Chemical compound C([C@H]1[C@@H](C)C=CC2=CCC[C@@H]([C@H]12)OC(=O)[C@@H](C)CC)C[C@@H]1C[C@@H](O)CC(=O)O1 AJLFOPYRIVGYMJ-INTXDZFKSA-N 0.000 description 1
- BOZILQFLQYBIIY-UHFFFAOYSA-N mevastatin hydroxy acid Natural products C1=CC(C)C(CCC(O)CC(O)CC(O)=O)C2C(OC(=O)C(C)CC)CCC=C21 BOZILQFLQYBIIY-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002674 ointment Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Landscapes
- Road Paving Structures (AREA)
Abstract
COMPOSITE ARCH STRUCTURE
ABSTRACT OF THE DISCLOSURE
A composite arch structure and method of making it are taught. The composite arch structure comprises a pair of retaining wall portions (2,3) and a top arch portion (4) extending therebetween. A stiffening and load distributing member (10) is structurally affixed to the top arch portion and extends longitudinally of the composite arch structure for the majority of the length of the structure. The composite arch structure preferably also includes longitudinally extending, load spreading buttress means (7,8) on either side of the vertical axis of the structure at positions where a radial force acting on the structure forms an angle of about 45° or more to the horizontal.
ABSTRACT OF THE DISCLOSURE
A composite arch structure and method of making it are taught. The composite arch structure comprises a pair of retaining wall portions (2,3) and a top arch portion (4) extending therebetween. A stiffening and load distributing member (10) is structurally affixed to the top arch portion and extends longitudinally of the composite arch structure for the majority of the length of the structure. The composite arch structure preferably also includes longitudinally extending, load spreading buttress means (7,8) on either side of the vertical axis of the structure at positions where a radial force acting on the structure forms an angle of about 45° or more to the horizontal.
Description
COMPOSITE ARCH STRUCTURE
The invention relates to new and useful improvem~nts in composite arch structures oE relatively large dimension, and more partictllarly to the provision of a stiffening and lo~d distributing member, structurally connected to the top arch portion of the composite arch.
As used herein and in the claims, the term "composite arch structl~e" is intended to include arch structures ha~ing any one o a number o cross sectional conEiguratlons, well known in the art, such as circular, pipe arch, vertical ellipse, horiæontal ellipse, underpass, arch, low profila ~rch, high profile arch and inverted pe~r.
In recent years, c~nventional rigid arch designs have been superseded by relatively flexible designs utilizing ~lexible retaining wall struc~ures similar to those described in Unlted States o America Patent 3,282,056.
The strength o~ these structur~s is derived primnrily from the backill material located thereabout. The structure, made up of curved, corrugated sheets, must have su~1clent strength to be capable of self support during in~tallation. The strength of the metallic structurP, on the other hand, is not suficient to support the superimposed load after installation. Whila its s-trength must be adequate to earry its share oE the sup~rlmposed load a~ter ins~allation, th~ backflll ma~erial i~ in~ended to be the princip~l load be~ring and transmi~tin~ elemen~
oE the -Einishe~d structure.
The design ~eatures oE structures o~ ~his sort, u~ili2ing t`he composite ar~h principla~ are dependent upon the shear and compression values of the backill material~
the proper related curvatures o the flexible lining and the type of backfill material enveloping ~he underground structure wh~n finished. So long as the dimensions of ~he 3S composite arch s~ructure remain relatively small, no dif~culty is encountered in the backfilling procedure~
.~ , ~.~
`'~`'A~
More recently, prior art workers have turned their atten~ion to the construction of so called "long-span"
composite arch structures, generally defined as having a span greater than 15 feet to about 25 feet and a minim~tm radius of curvature of from about ~ Eeet to about 12 feet.
Examples of such long span composite arch structures are taught, for example, in United States of America Pa~ents 39508,406 and 3,735,595.
Long-span struc~ures are characterized by certain difficulties generally not encountered wit~ the smaller structures. For one thing, they ha~e less inltial stability until supported by ~he backill material and the back~illing procedure is far more critical. For example, as the backLll progresses upwardly along the flexi~le retaining wall portions of the composite arch structure, the top arch portion tends to shi~t upwardly at its center or "peak". To overcome this problem, the center part oE
the top arch portion may be loaded or held in place and in shape in~ernally by ~rame members, cables or the like.
Further difficulties are encountered when backfilling and compac~ing the soil along or around ths junctlon lines between the flex~ble retaining walls ~which ha~e a relatively sharp curvature and are situated substantially vertically) and the flexlble arch which extends therebetween. As the compa~tion proceeds, the hor~æontal component of the load becom~s greater ~han the vertical component, ~hus causlng d-Lstortion of tha structure which can only be avoided bg extrPmel~ care~ul backfilling Erom bot~ s~das~
3Q Prior art workers have developed a number o:E expedients to overcome these dlfficulties. For example, the composite arch structure may be provided with open-top bins located along the upper surface of the liner.
B~ckfill material is compacted in layers in tha bins and around the liner, the blns serving to confine, reinorce and strengthen tha compac~ed backfill, as well as acting as sti~feners for the top arch portion of the liner to reduce initial peaking and subsequent 1attening. Such a structure i~ taught~ in the above mentionèd U.S. Patent 3,735,595.
Another expedient is to provide circu~ferential rib stiffeners about the liner. Thes~ r-lb stiffeners provide increased stifness to reduce peaking during backfilling.
They further reduce local buckling and e~cessive flattening during the remainder of the backilling procedureO
Yet another expedient is set forth in the above mentioned U.S. Patent 3,508,406 wherein longtitudinally extending load spreading buttress means are provided on the composite arch structure, located to either side of the vertical axis thereof at positions where the radial ~orce acting on ~he s-tructure orms an angle oE about 45 or more to the horizontal. These buttress means anchor the base o the top arch portion of the structure and provide lengths of consolidated material at the locations where compaction and backfilling equipment cannot effectively work, enabling the baekfilling procedure to continue without distortion of the structure. For vPry wide arches~ one or more sti~ening members extending between the buttress means and over the top arch portion of ~he structure m~y be provided, the top arch portlon o~
the structure being affixed ~o the sti~ening me~bers.
T~e American Association of State High~ay and Transportation OEic1als (A~SH~O) has devised a serles o~
standard specifications ~or hi~hway bridges, includlng long-span composite arch struc~ures o~ the ~ype to which the present invan~i~n i9 direc~ed. ~o date; such struc~ure~ have been bullt with sp~ms up to 51 Eee~ ~16m).
It is presently generally accepted that the top arch portion o~ such structures is limited to from about a 60 to ~bout an ~0 central angle.
AASHTO Standards also set forth the minimum amount of cover or backfill to be located over the structure in order for the structure to per~orm properly. Where less than minimum overhead cover is applied~ loads are not properly distributed through the soil and the soil or backfill does not sustain its preponderant share of the load. For example, under live load such ~s that lmposed S by a vehicle, failure can occur b~cause this load is localized and applied to the area of the arch immediately below the point of load application. In situatlons where only minimum or less than minimum backfill can be applled to the top arch portion of the liner structure, prior ~rt workers ha~e provided an elongated slab of reinforced concre~e located ~bove the liner structure and near or immedlately below the surface of the road extending across - the shallow back~ill cover. The elongated slab extends sub~tantially the leng~h oE the l-Lne~ s~ruc~ure and serves as a load spreading device.
The present invention is based upon the discovery that if, in a long span composite arch structure, a longitudinally extending stiffening element is structurally connected to the center of the top arch structure, extending substantially the length of the structure, a number o~ sdvantages are obtained. First of all, the stif~ning element, being structurally connected to the center oE the top arch portion o~ the linPr structure~ ser~es as an arch "interrupter". In other words, that portion o~ the arch to which the stlf~ening elemen~ is connected is~ itsel, stiE~ened. ~he remalnder o~ the arch structure rema m 9 ~lexible~ cap.~bla of ylelding to develop adequa~e soil arching. Nevertheless, the central angle of the structure has been subdivicled into ~Q lesser angles9 a~ ~as the chor~ of the top arch portion. As a result, the top arrh portion has baen additionally rigidi~ied. ~he top arch portion rlgidity is approximately an inverse function of the square o the chord length or the angles subtended by the top arch portion ~nd the s~gments into which it is divided. As a result of this, through the practice of the present invention the central angle of long span structure can safely be increased up to ~0 or more and the span width may be increased up to about 60 fee~.
Fur~hermore, the stiffening element can s~rve as top weighting for the structure, minimizing or preventing peaking during the backfilling operation. The stif~ening element will serve as a live~ thermal and dead load dis~ribu~or, providing a sound structure even in circums~ances where less than minimum recommended bac~
cover must be used.
According to the invention there is provided a - composite arch s~ructure of the type comprising an elongated, relatively thin gauge liner with c3mpacted backfill thereabout, said llner comprising flrst and second flexible retaining wall portions and a 1exible top arch portion extending therebetween, said first and second retaining walls having longitudinally ex~endlng upper edges, said top arch portion having longitudinally extending upper edges, said top arch portion having longitudinally extending lateral edges afixed respectively to said upper edges of said first and second retaining ~all portions, characterized by a stif~enlng and load distributing member structurally connected to said top arch portion and extending cantrally and lon$1tudinall~ o~ sa~d top arch portion Eor ~he majority at least oE the langth thareo.
In one ~mbodiment, tha stlf~ening and load distributing mem~er comprises a relnorced concreta slab cast along the cent~rmost part o~ the top arch portion~ on the upper side thereo~
In another embodiment a longitudinally extending pair of structural mem~ers such as angles are afixed to the top arch portion ln parallel spaced relationlship, su~stantially equidistant from the centerline of the top arch portion.
~8~
The in~ention further provides a method o~ constructing a composite arch structure of the type comprising an elongated relatively thln gauge liner with compacted back~ill thereabout, said liner comprising a pair of ~lexible retaining ~all por~ions connected a~ their upper longitudinal edges to a top arch portion ex~ending therebetweeng comprising the steps of assembling said liner in sltu~ characterized by struc~urally connecting to said top arch portion o said liner an elongated stiffening and load distributing member longitudinally and centrally of said top arch structure and back:Eilling and compacting backfill material about said liner and said sti~fening and load distributing member.
Reference i~ made to the accompanying drawings wherein:
Figure l is a transverse, cross sectional, elevational view of a composl~e areh structure of the present invention sho~n in situ.
Figure 2 is a fragmentary, enlarged, cross sectional view, illustrating the central part of the top arch portion of the structure o~ Figure 1 with the sti~fening and load distributing member structurally connected thqreto .
Figure 3 is a longi~udinal, cross sectional, elev~ional view of the composite arch structure of Figure 1.
Figure 4 is a ~ragmentary perspective vlew o the composite arch structure o:E Figure 1 provided with transverse stiffening members extending between the bu`ttress means and t~rough the sti~ening and load distri~utin$ memeber of the present invention, Flgure 5 ls a ~ragmentary cross sectional view illustrating an alterna~e form of ~he stifening and load distributing member o the present invention.
Figures 6 through lO are fragmentary cross sectional 3S vie~s illustrating alternate orms of stiffeners to be used in place of the buttress means of Figures 1 through 3.
Refarence is made to igures l, 2 and 3 wherein like parts have been given like index numerals. As is most clearly seen in Figure 1, the composi.te arch structure comprises a liner ~generally indicated at l), having a pair o~ flexible retaining wall portions 2 and 3 and a top arch por~ion 4 extending therebetwe~n, The liner is made of relatively thin gauge corrugated metallic pla~es having their edges lapped and bol~ed together. While the Figures do not illustrate the indivldual plates of the liner, this construction is conventional and well known in the ar~.
For purposes of an exemplary showing, the liner 1 is illustrated as being o~ the high profile arch type. It will be understood by one skilled in the art that the lnv~ntion is applicable to liners of . any o the well known cross sec~ional configurations mentloned above.
The lowermost edges of the 1exible retainlng wall portions 2 and 3 may be suppor~ed by Eooters 5 and 6 which may be o the type described in U.S. Patent 3,508,406 or U.S. Patent 4,~10,617. The precise nature of foo~ers 5 20 and 6 can vary and doe~ not constitute a limitation of the prese.nt invention. Some composite arch structures do not need footers.
While not required, it is preerred that the liner l be provided with lonxitudinally extending buttress means 7 and 8, o~ tha type dascribed in the above mentioned U.S.
Patent 3,$08,406. The buttress means 7 and 8 are generally reinforced concrete members shear connected to the linex 1 and normally CRS~ in place once the compacted ~ck~ill material 9 has reached a he~ght on each side o 3n the struc~ure ~ust below t~e positlon o buttress means 7 and ~.
Buttress means 7 and 8 generally extend the majority of the length of liner 1 (see Figure 3) and are located alon`g the ~unc~ure of the flexible retaining wall portions
The invention relates to new and useful improvem~nts in composite arch structures oE relatively large dimension, and more partictllarly to the provision of a stiffening and lo~d distributing member, structurally connected to the top arch portion of the composite arch.
As used herein and in the claims, the term "composite arch structl~e" is intended to include arch structures ha~ing any one o a number o cross sectional conEiguratlons, well known in the art, such as circular, pipe arch, vertical ellipse, horiæontal ellipse, underpass, arch, low profila ~rch, high profile arch and inverted pe~r.
In recent years, c~nventional rigid arch designs have been superseded by relatively flexible designs utilizing ~lexible retaining wall struc~ures similar to those described in Unlted States o America Patent 3,282,056.
The strength o~ these structur~s is derived primnrily from the backill material located thereabout. The structure, made up of curved, corrugated sheets, must have su~1clent strength to be capable of self support during in~tallation. The strength of the metallic structurP, on the other hand, is not suficient to support the superimposed load after installation. Whila its s-trength must be adequate to earry its share oE the sup~rlmposed load a~ter ins~allation, th~ backflll ma~erial i~ in~ended to be the princip~l load be~ring and transmi~tin~ elemen~
oE the -Einishe~d structure.
The design ~eatures oE structures o~ ~his sort, u~ili2ing t`he composite ar~h principla~ are dependent upon the shear and compression values of the backill material~
the proper related curvatures o the flexible lining and the type of backfill material enveloping ~he underground structure wh~n finished. So long as the dimensions of ~he 3S composite arch s~ructure remain relatively small, no dif~culty is encountered in the backfilling procedure~
.~ , ~.~
`'~`'A~
More recently, prior art workers have turned their atten~ion to the construction of so called "long-span"
composite arch structures, generally defined as having a span greater than 15 feet to about 25 feet and a minim~tm radius of curvature of from about ~ Eeet to about 12 feet.
Examples of such long span composite arch structures are taught, for example, in United States of America Pa~ents 39508,406 and 3,735,595.
Long-span struc~ures are characterized by certain difficulties generally not encountered wit~ the smaller structures. For one thing, they ha~e less inltial stability until supported by ~he backill material and the back~illing procedure is far more critical. For example, as the backLll progresses upwardly along the flexi~le retaining wall portions of the composite arch structure, the top arch portion tends to shi~t upwardly at its center or "peak". To overcome this problem, the center part oE
the top arch portion may be loaded or held in place and in shape in~ernally by ~rame members, cables or the like.
Further difficulties are encountered when backfilling and compac~ing the soil along or around ths junctlon lines between the flex~ble retaining walls ~which ha~e a relatively sharp curvature and are situated substantially vertically) and the flexlble arch which extends therebetween. As the compa~tion proceeds, the hor~æontal component of the load becom~s greater ~han the vertical component, ~hus causlng d-Lstortion of tha structure which can only be avoided bg extrPmel~ care~ul backfilling Erom bot~ s~das~
3Q Prior art workers have developed a number o:E expedients to overcome these dlfficulties. For example, the composite arch structure may be provided with open-top bins located along the upper surface of the liner.
B~ckfill material is compacted in layers in tha bins and around the liner, the blns serving to confine, reinorce and strengthen tha compac~ed backfill, as well as acting as sti~feners for the top arch portion of the liner to reduce initial peaking and subsequent 1attening. Such a structure i~ taught~ in the above mentionèd U.S. Patent 3,735,595.
Another expedient is to provide circu~ferential rib stiffeners about the liner. Thes~ r-lb stiffeners provide increased stifness to reduce peaking during backfilling.
They further reduce local buckling and e~cessive flattening during the remainder of the backilling procedureO
Yet another expedient is set forth in the above mentioned U.S. Patent 3,508,406 wherein longtitudinally extending load spreading buttress means are provided on the composite arch structure, located to either side of the vertical axis thereof at positions where the radial ~orce acting on ~he s-tructure orms an angle oE about 45 or more to the horizontal. These buttress means anchor the base o the top arch portion of the structure and provide lengths of consolidated material at the locations where compaction and backfilling equipment cannot effectively work, enabling the baekfilling procedure to continue without distortion of the structure. For vPry wide arches~ one or more sti~ening members extending between the buttress means and over the top arch portion of ~he structure m~y be provided, the top arch portlon o~
the structure being affixed ~o the sti~ening me~bers.
T~e American Association of State High~ay and Transportation OEic1als (A~SH~O) has devised a serles o~
standard specifications ~or hi~hway bridges, includlng long-span composite arch struc~ures o~ the ~ype to which the present invan~i~n i9 direc~ed. ~o date; such struc~ure~ have been bullt with sp~ms up to 51 Eee~ ~16m).
It is presently generally accepted that the top arch portion o~ such structures is limited to from about a 60 to ~bout an ~0 central angle.
AASHTO Standards also set forth the minimum amount of cover or backfill to be located over the structure in order for the structure to per~orm properly. Where less than minimum overhead cover is applied~ loads are not properly distributed through the soil and the soil or backfill does not sustain its preponderant share of the load. For example, under live load such ~s that lmposed S by a vehicle, failure can occur b~cause this load is localized and applied to the area of the arch immediately below the point of load application. In situatlons where only minimum or less than minimum backfill can be applled to the top arch portion of the liner structure, prior ~rt workers ha~e provided an elongated slab of reinforced concre~e located ~bove the liner structure and near or immedlately below the surface of the road extending across - the shallow back~ill cover. The elongated slab extends sub~tantially the leng~h oE the l-Lne~ s~ruc~ure and serves as a load spreading device.
The present invention is based upon the discovery that if, in a long span composite arch structure, a longitudinally extending stiffening element is structurally connected to the center of the top arch structure, extending substantially the length of the structure, a number o~ sdvantages are obtained. First of all, the stif~ning element, being structurally connected to the center oE the top arch portion o~ the linPr structure~ ser~es as an arch "interrupter". In other words, that portion o~ the arch to which the stlf~ening elemen~ is connected is~ itsel, stiE~ened. ~he remalnder o~ the arch structure rema m 9 ~lexible~ cap.~bla of ylelding to develop adequa~e soil arching. Nevertheless, the central angle of the structure has been subdivicled into ~Q lesser angles9 a~ ~as the chor~ of the top arch portion. As a result, the top arrh portion has baen additionally rigidi~ied. ~he top arch portion rlgidity is approximately an inverse function of the square o the chord length or the angles subtended by the top arch portion ~nd the s~gments into which it is divided. As a result of this, through the practice of the present invention the central angle of long span structure can safely be increased up to ~0 or more and the span width may be increased up to about 60 fee~.
Fur~hermore, the stiffening element can s~rve as top weighting for the structure, minimizing or preventing peaking during the backfilling operation. The stif~ening element will serve as a live~ thermal and dead load dis~ribu~or, providing a sound structure even in circums~ances where less than minimum recommended bac~
cover must be used.
According to the invention there is provided a - composite arch s~ructure of the type comprising an elongated, relatively thin gauge liner with c3mpacted backfill thereabout, said llner comprising flrst and second flexible retaining wall portions and a 1exible top arch portion extending therebetween, said first and second retaining walls having longitudinally ex~endlng upper edges, said top arch portion having longitudinally extending upper edges, said top arch portion having longitudinally extending lateral edges afixed respectively to said upper edges of said first and second retaining ~all portions, characterized by a stif~enlng and load distributing member structurally connected to said top arch portion and extending cantrally and lon$1tudinall~ o~ sa~d top arch portion Eor ~he majority at least oE the langth thareo.
In one ~mbodiment, tha stlf~ening and load distributing mem~er comprises a relnorced concreta slab cast along the cent~rmost part o~ the top arch portion~ on the upper side thereo~
In another embodiment a longitudinally extending pair of structural mem~ers such as angles are afixed to the top arch portion ln parallel spaced relationlship, su~stantially equidistant from the centerline of the top arch portion.
~8~
The in~ention further provides a method o~ constructing a composite arch structure of the type comprising an elongated relatively thln gauge liner with compacted back~ill thereabout, said liner comprising a pair of ~lexible retaining ~all por~ions connected a~ their upper longitudinal edges to a top arch portion ex~ending therebetweeng comprising the steps of assembling said liner in sltu~ characterized by struc~urally connecting to said top arch portion o said liner an elongated stiffening and load distributing member longitudinally and centrally of said top arch structure and back:Eilling and compacting backfill material about said liner and said sti~fening and load distributing member.
Reference i~ made to the accompanying drawings wherein:
Figure l is a transverse, cross sectional, elevational view of a composl~e areh structure of the present invention sho~n in situ.
Figure 2 is a fragmentary, enlarged, cross sectional view, illustrating the central part of the top arch portion of the structure o~ Figure 1 with the sti~fening and load distributing member structurally connected thqreto .
Figure 3 is a longi~udinal, cross sectional, elev~ional view of the composite arch structure of Figure 1.
Figure 4 is a ~ragmentary perspective vlew o the composite arch structure o:E Figure 1 provided with transverse stiffening members extending between the bu`ttress means and t~rough the sti~ening and load distri~utin$ memeber of the present invention, Flgure 5 ls a ~ragmentary cross sectional view illustrating an alterna~e form of ~he stifening and load distributing member o the present invention.
Figures 6 through lO are fragmentary cross sectional 3S vie~s illustrating alternate orms of stiffeners to be used in place of the buttress means of Figures 1 through 3.
Refarence is made to igures l, 2 and 3 wherein like parts have been given like index numerals. As is most clearly seen in Figure 1, the composi.te arch structure comprises a liner ~generally indicated at l), having a pair o~ flexible retaining wall portions 2 and 3 and a top arch por~ion 4 extending therebetwe~n, The liner is made of relatively thin gauge corrugated metallic pla~es having their edges lapped and bol~ed together. While the Figures do not illustrate the indivldual plates of the liner, this construction is conventional and well known in the ar~.
For purposes of an exemplary showing, the liner 1 is illustrated as being o~ the high profile arch type. It will be understood by one skilled in the art that the lnv~ntion is applicable to liners of . any o the well known cross sec~ional configurations mentloned above.
The lowermost edges of the 1exible retainlng wall portions 2 and 3 may be suppor~ed by Eooters 5 and 6 which may be o the type described in U.S. Patent 3,508,406 or U.S. Patent 4,~10,617. The precise nature of foo~ers 5 20 and 6 can vary and doe~ not constitute a limitation of the prese.nt invention. Some composite arch structures do not need footers.
While not required, it is preerred that the liner l be provided with lonxitudinally extending buttress means 7 and 8, o~ tha type dascribed in the above mentioned U.S.
Patent 3,$08,406. The buttress means 7 and 8 are generally reinforced concrete members shear connected to the linex 1 and normally CRS~ in place once the compacted ~ck~ill material 9 has reached a he~ght on each side o 3n the struc~ure ~ust below t~e positlon o buttress means 7 and ~.
Buttress means 7 and 8 generally extend the majority of the length of liner 1 (see Figure 3) and are located alon`g the ~unc~ure of the flexible retaining wall portions
2 and 3 and the Elexible top arch portion 4. Stated anot~er way? the buttress means 7 and 8 are located on ~ 2 ~ ~
either ~ide oE the liner l at positions where a radial force acting on the struc~ure forms an angle of about 45 or ~ore to the horizontal...
Buttress means 7 and 8 serve a number of important purposes. First of all, they tend to anchor the base parts of top arch portion 4 and the upper parts of retaining wall portions 2 and 3. The bu~tress means provide s~pport and a vertical wall against which the backfill material can be compacted, spreading the load over a greater area a~ this vi~al point oE the back~illing and compactin~ procedures. Since ~he top arch portion 4 is flexible, care must be taken during this portion o the back~illing and compacting procedure up to and including but~ress means 7 and 8 to prevent the top arch portion from shifting upwardly at itq center or "peaking". On the other hand~ when the top cover portion oE the backfill is located in place and compacted~ the top arch portion 4 will tend to move downward. At the present time, it is generally accepted t~at the angle A subtended by the top arch section 4 should not exceed about 80. With s~ructuras o:E relatively large span, the above mentioned U.S. Patent 3,50~,406 recom~ends the provision o~ arcuate curved reinforcing and stabili~ing members over-spanning the top arch portion 4 and a~Eixed at their ends ~o buttress means 7 and 8. These stl~Eening ~embars are curved to ~ollow the curvature oE the top arcll portlon 4 an~ are afEixed thereto~
Ano~her considera~ion in ~h~ construction oE
long-span ~tructure~ o the typa contemplàted by this inven~ion has to do with the amoun~ of cover or backfill placed and compacted over the top oE the top arch portion 4. The cover should be sufficient to enable the backfill to accept its proponderant portion of the load to which the composite arch structure will be subjected.
-35 Otherwise, the liner l will be subjected to a p~
disproportionate amount of load which might lead to defor~ation or failure. AASHTO specifications set forth minimum cover stan,dards for structures of various sizes utilizing liners of various gauges.
The present invention is based upon the discovery that a stiffening and load distributing member~ when structurally connected to the top arch portion 4 of the liner by shear connectors or other appropriate means, will rigidify the top arch portion 4 so that it will maintain its proper configura~ion during the backfilling and compacting procedures, enabling structures of greater span to be produced, and in shallow cover situations reducing the minimum amount of cover required. The top stiffening and load distributing element can be of any appropria~e material, made in any appropriate manner so long as it possesse's certain structural performance characteristics such as adequate compression characteristics tthrust reslstance), adequate shear resistance (resistance to transverse movement with respect to the liner 1) and ~0 moment characteristics (adequate stiffness or bending strength). All of these characteristics should be present under live~ thermal and dead load conditions. T~e top - sti~ening and load distributing member could, for example, itself be abricated oE metal or th~ like. For purposes o~ an exemplary illustration, t~e ~op stiE~ening and load distrlbuting member will 'be described as an elongated, rainfor~ed~ concrete slab or beam. Such a concre~e slab or beam has a number of advan-~ages in ~a~
it is ea~ An~ lnexpenslve ~o manu~aa~ure and has su~icient wei~h~ or mass ~o serve as a top loading alement ~o minimize pea~ing during ~he early stages oE the backfilling and compacting procedure. Such a concrete stiffening and load distributing member is shown in Figures 1 through 3 at l~. As will be evident from Figure 3S 3, the slab lO ex~ends substantially the length of liner ~'V~
1, along the center of the top arch portion (see also Figure 1).
It is important that t~e slab 10 be af~ixed to the top arch portion 4 by shear connectors or other S appropriate means. When shear connectors are used they may be of any well known type. For example, they may constitute bolts affixed to the top arch portion 4 and extending thereabove, or they may be elements welded to the upper surface of the top arch portion 4. Such welded shear connectors are illustrated in Figure 2 at 11.
Figure 2 also illustrates relnforc;ng members or bars located within the slab 10. The bars 12 exten~
longitudinally of the slab and additional barq extend transversely of the slab, one of which is shown at 12a.
That p~rt of top arch portion 4 immediately beneath slab 10 is now rigid and no longer ~lexible because o the connection of slab 10 to that part of top arch portion 4.
The original flexible arch subtending angle A has now been divided in~o two shorter equal flexible top arch portions 4a and 4b, each subtending a small angle B. Thus, slab 10 serves as an "interrupter", dividing the single flexible top arch portion 4 into t~o smaller flexible top arch portions 4a and 4b. The rigidi~y of top arch portion 4 is approximately an înverse unction o the square of the angle subtended thereby. Thus, the rigidi~y (R) o~ top arch por~ion 4 may be ~et Eorth as ollows:
R = ~A)2 Thus, 1~ angla ~ is 80 and aach Q~ the an~les B is abou~
30 3 the top arch portion 4 i9 llOW about 7 times more rigid by ~irtue o the pra~ance o;~ slab lQ. A~ a result o this~ the central angle A oE structures o ~his sort can~ in the practlce o~ ~he present invention, be increased safely up to about 90~ or more. In addi~ion, long span structurAes can be made safely having a span ! 35 width up to abou~ 60 ~eet.
2~GI
For purpo~es of an exemplary showing, the composite arch structure of Figure3 1 through 3 is illu~trated in a shallow cover configuration surmounted by a roadway surface 13.
A ~rue soil arch is not formed until the amount o cover backfill reaches the point that, adding more will not increase the load on the liner 1. As indicated above, M SHT0 standards have been set for minimum cover for variou sizes o~ structure and gauge of metal used in the liner. Below these l~mits, ~he live~ thermal and dead load~ could exceed the design capability o~ the liner~
resulting in failure of the structure. In situations -having le.qs than minimum overhead cover, the~e loads are not distr~buted over the entire structure and failure can occur because some of these load~ can become localized and applied directly to the liner 1. For example, in the embodiment illustrated in Figures 1 through 3, the live load of a vehicle pa~sing over the structure could be localized ~nd applied to the area of the liner immediately below the point o application. However, with the slab 10 mounted on the liner, 3uch a load is distributed substantially over the entire liner with the result that minimum or less than minimum cover can be sa~ely used. -` In the embodlment o Figures 1 through 3, the slab can be poured immediately after as3embly of liner l.
Preferably, however, the s~ab 10 or lOa is poured at about the same time the buttress mean~ 7 and 8 are poured, if.
buttress means axe used~ The slab 10, for example, can be . poured using a crane with a concrete bucket or concrete trucks with chutes. It would not be neces~ary to drive a concrete truck onto the crown or top arch portion 4 o liner 1.
Figure 4 is a perspective view of a composite arch structure similar to ~hat of Fi~ure l but having a span in excess of abou~ 50 feet~ The liner is gener~lly indicated `
...~ . ~
2~ ~
at lh~,and comprises a pair of 1exlble retaining wall portions 15 and 16 and a top arch portion 17. As in the case of the structure of Figure 1, ~he composite arch structure of Figure 4 is provided with footers 18 and 19 and buttress means 20 and 21.
In structur2s having a maximum span greater than about 50 eet it has often been found advantageous to provide a plurality of transverse stifenin~ members of the type taught in the above mentioned U.S. Patent
either ~ide oE the liner l at positions where a radial force acting on the struc~ure forms an angle of about 45 or ~ore to the horizontal...
Buttress means 7 and 8 serve a number of important purposes. First of all, they tend to anchor the base parts of top arch portion 4 and the upper parts of retaining wall portions 2 and 3. The bu~tress means provide s~pport and a vertical wall against which the backfill material can be compacted, spreading the load over a greater area a~ this vi~al point oE the back~illing and compactin~ procedures. Since ~he top arch portion 4 is flexible, care must be taken during this portion o the back~illing and compacting procedure up to and including but~ress means 7 and 8 to prevent the top arch portion from shifting upwardly at itq center or "peaking". On the other hand~ when the top cover portion oE the backfill is located in place and compacted~ the top arch portion 4 will tend to move downward. At the present time, it is generally accepted t~at the angle A subtended by the top arch section 4 should not exceed about 80. With s~ructuras o:E relatively large span, the above mentioned U.S. Patent 3,50~,406 recom~ends the provision o~ arcuate curved reinforcing and stabili~ing members over-spanning the top arch portion 4 and a~Eixed at their ends ~o buttress means 7 and 8. These stl~Eening ~embars are curved to ~ollow the curvature oE the top arcll portlon 4 an~ are afEixed thereto~
Ano~her considera~ion in ~h~ construction oE
long-span ~tructure~ o the typa contemplàted by this inven~ion has to do with the amoun~ of cover or backfill placed and compacted over the top oE the top arch portion 4. The cover should be sufficient to enable the backfill to accept its proponderant portion of the load to which the composite arch structure will be subjected.
-35 Otherwise, the liner l will be subjected to a p~
disproportionate amount of load which might lead to defor~ation or failure. AASHTO specifications set forth minimum cover stan,dards for structures of various sizes utilizing liners of various gauges.
The present invention is based upon the discovery that a stiffening and load distributing member~ when structurally connected to the top arch portion 4 of the liner by shear connectors or other appropriate means, will rigidify the top arch portion 4 so that it will maintain its proper configura~ion during the backfilling and compacting procedures, enabling structures of greater span to be produced, and in shallow cover situations reducing the minimum amount of cover required. The top stiffening and load distributing element can be of any appropria~e material, made in any appropriate manner so long as it possesse's certain structural performance characteristics such as adequate compression characteristics tthrust reslstance), adequate shear resistance (resistance to transverse movement with respect to the liner 1) and ~0 moment characteristics (adequate stiffness or bending strength). All of these characteristics should be present under live~ thermal and dead load conditions. T~e top - sti~ening and load distributing member could, for example, itself be abricated oE metal or th~ like. For purposes o~ an exemplary illustration, t~e ~op stiE~ening and load distrlbuting member will 'be described as an elongated, rainfor~ed~ concrete slab or beam. Such a concre~e slab or beam has a number of advan-~ages in ~a~
it is ea~ An~ lnexpenslve ~o manu~aa~ure and has su~icient wei~h~ or mass ~o serve as a top loading alement ~o minimize pea~ing during ~he early stages oE the backfilling and compacting procedure. Such a concrete stiffening and load distributing member is shown in Figures 1 through 3 at l~. As will be evident from Figure 3S 3, the slab lO ex~ends substantially the length of liner ~'V~
1, along the center of the top arch portion (see also Figure 1).
It is important that t~e slab 10 be af~ixed to the top arch portion 4 by shear connectors or other S appropriate means. When shear connectors are used they may be of any well known type. For example, they may constitute bolts affixed to the top arch portion 4 and extending thereabove, or they may be elements welded to the upper surface of the top arch portion 4. Such welded shear connectors are illustrated in Figure 2 at 11.
Figure 2 also illustrates relnforc;ng members or bars located within the slab 10. The bars 12 exten~
longitudinally of the slab and additional barq extend transversely of the slab, one of which is shown at 12a.
That p~rt of top arch portion 4 immediately beneath slab 10 is now rigid and no longer ~lexible because o the connection of slab 10 to that part of top arch portion 4.
The original flexible arch subtending angle A has now been divided in~o two shorter equal flexible top arch portions 4a and 4b, each subtending a small angle B. Thus, slab 10 serves as an "interrupter", dividing the single flexible top arch portion 4 into t~o smaller flexible top arch portions 4a and 4b. The rigidi~y of top arch portion 4 is approximately an înverse unction o the square of the angle subtended thereby. Thus, the rigidi~y (R) o~ top arch por~ion 4 may be ~et Eorth as ollows:
R = ~A)2 Thus, 1~ angla ~ is 80 and aach Q~ the an~les B is abou~
30 3 the top arch portion 4 i9 llOW about 7 times more rigid by ~irtue o the pra~ance o;~ slab lQ. A~ a result o this~ the central angle A oE structures o ~his sort can~ in the practlce o~ ~he present invention, be increased safely up to about 90~ or more. In addi~ion, long span structurAes can be made safely having a span ! 35 width up to abou~ 60 ~eet.
2~GI
For purpo~es of an exemplary showing, the composite arch structure of Figure3 1 through 3 is illu~trated in a shallow cover configuration surmounted by a roadway surface 13.
A ~rue soil arch is not formed until the amount o cover backfill reaches the point that, adding more will not increase the load on the liner 1. As indicated above, M SHT0 standards have been set for minimum cover for variou sizes o~ structure and gauge of metal used in the liner. Below these l~mits, ~he live~ thermal and dead load~ could exceed the design capability o~ the liner~
resulting in failure of the structure. In situations -having le.qs than minimum overhead cover, the~e loads are not distr~buted over the entire structure and failure can occur because some of these load~ can become localized and applied directly to the liner 1. For example, in the embodiment illustrated in Figures 1 through 3, the live load of a vehicle pa~sing over the structure could be localized ~nd applied to the area of the liner immediately below the point o application. However, with the slab 10 mounted on the liner, 3uch a load is distributed substantially over the entire liner with the result that minimum or less than minimum cover can be sa~ely used. -` In the embodlment o Figures 1 through 3, the slab can be poured immediately after as3embly of liner l.
Preferably, however, the s~ab 10 or lOa is poured at about the same time the buttress mean~ 7 and 8 are poured, if.
buttress means axe used~ The slab 10, for example, can be . poured using a crane with a concrete bucket or concrete trucks with chutes. It would not be neces~ary to drive a concrete truck onto the crown or top arch portion 4 o liner 1.
Figure 4 is a perspective view of a composite arch structure similar to ~hat of Fi~ure l but having a span in excess of abou~ 50 feet~ The liner is gener~lly indicated `
...~ . ~
2~ ~
at lh~,and comprises a pair of 1exlble retaining wall portions 15 and 16 and a top arch portion 17. As in the case of the structure of Figure 1, ~he composite arch structure of Figure 4 is provided with footers 18 and 19 and buttress means 20 and 21.
In structur2s having a maximum span greater than about 50 eet it has often been found advantageous to provide a plurality of transverse stifenin~ members of the type taught in the above mentioned U.S. Patent
3,508,406. Two such stiffening members are shown in Figure 4 at 22 and 23. The stiffening ~embers conform to the shape of the top arch portion 4 and overspan the top arch portion in parallel spaced relationship. The ends oE
stiffening members 22 and 23 are appropriately affixed to buttress means 20 and 21. If desired, the top arch portion 17 can be connected.to the stifening members 22 and 23 by bolts or other appropriate fastening means.
The embodiment of Figure 4 is also provided with the stifening and load distributing member of thP present invention~ indicated at ~4. For purposes oE an exemplary showing, the stifening and load distributin~ member 24 is illustrated as being a reinforcad concrete sl~b poured in place and d~rectly over sti~ning members 22 and 23 which extend therethrou~h. In thls way, the s~iEfenlng m2mbers serve as additional reinQr~man~ or the slab 2~ as well as reiaforcing and stabilizillg means for the ~op arc~
~ortion~ preventing ~agglng o -~he top arch portion dua t~
the s~atic load inharen~ ln the cons~ructlQn oE such long~span structures.
~s indica~e~ above, ~he stlE~ening and load distrubutlng member oE the presPnt invention need not take the form of a reinorced concrete slab. Figure S is a ragmentary cross sectional view oE top ~rch por.ion 4, similar to Figure 2. In this instance~ the slab 10 has ~een replaced by pairs o longitudinally extending angles 25-26 and 27-28. Angles 25~26 are located directly opposite each other on the top and bottom surfaces of the top arch portion 4, as shown. The same is true of angles ` 27-28. The angle palrs 25-26 and 27W28 are loca~ed in p~rallel spaced relationship and are substantially equally spaced to eit~er side of the centerline of ~he top arch portion 4. The angle pairs may be attached to the top arch portion 4 by a plurality of bolts (two of which are shown at 29 and 30), or by any other appropriate fastening means. The angle pairs 25~26 and 27-28 serv~ to align the corrugatlons of the adjacent liner plates andl together with that part of top arch portion 4 extending between the angle pairs, form an "I-beam" which serves substantially the same purposes as does slab 10 of Fi~ure 2. It would also be within the scope of the invention to provide angles 25 and 27 only or angles 26 and 28 only, depending upon the span of the liner. For longer span structures the provision of pairs of angles ~5-26 and 27-28 is preferred.
~igures 6 through 10 illustrate varlous types of longitudinal extending load spreading means which may be substituted or buttresses 7 and 8 in Figures l and 3. In Figure 6 liner 1 is shown ragmentarily, made up of retain~ng wall portion 2 and ~op arch portion ~. In ~his Figure buttress me~ns 7 has h~en replaced by a longitudinally extanding ang.le 31~ The lower leg o~ angle 31 ls a.~ixed ~o li~er 1 by an~ appropria~e means such as bol~s~ on~ o w~ich is shown at 32. ~hat leg o angle 31 abuttlng liner 1 may be sli~htly curved ~o conform to the 3U liner, i;E d~sired.
In Flgure 7 like parts hava baen given like index numerals and buttress means 7 has been replaced by a longitudinally extending T-beam 33 affixed to liner l by bolts or o~her appropriate means (not shown).
In Flgure 8 ~as in Eigures 9 and lO to be described hereina~ter) like p~rts have again been given like index 2~)~
, numerals. In this instance buttress means 7 has been replaced by a plurality of longitudinally extending, transversely curved corrugated me~al plates (two oE which ~re shown at 34 and 35) joined ~ogether by bolts ~one of which is shown at 36) and joined to the liner 1 by additional bolts (two of which are shown a~ 37 and 38).
The structure of Figure 8 may be filled with concrete or other consolidated material, if desired.
Figur~ 9 illustrates an H-beam 39 as a replacement ~or b1~ttress means 7. The H-beam 39 is af~ixed to liner 1 by a plurality of bolts (two of which are shown at 40 and 41) or other fastening means.
In Figure 10, buttress means 7 has been replaced by one or more longitudinally extending corrugated metalllc plates 42 connected to liner 1 by bolts 43 ~or other appropriats fastening means) lcca~ed along the longitudin~l edges and valleys of the plate 42.
EXAMPI.E
A composite arch structure o~ the type shown in Figures 1 through 3 was constructed. The liner was made of 1 gauge corrugated steel plates having a high arch profile~ a maximum span of 33 feet 1 inch and a height ~bove the ooters o 21 feet 6 inches. Buttresses of the type shown at 7 and 8 were provided~ and the stiEfening and load distributing member 10 constituted a reinEorced concrete member pourad at sub~-tantiall~ the same ~ime as tha but~ress means 7 and 8 were poured. The concre~e slab 10 was shear connec~ed to ~he ~op arch portion oE the struc~ure by w~lded shear conn~e~ors spaced on 24 inch centars along both the width and length o~ the concre~e slab. The concrete slab was 8 Eeet wida and 12 inches thick at the topmost portion of the top arch sec~ion. The slab extended subs~antially the entire length of the topmost part of the top arch portion, i.e., 32 feet. The bottom`center line length of the liner was 92 feet and the , top center line length thereof was 52 feet.
The AASHTO standard specifications call for a minimum cover or this type of structure of 3 feet. In the particular ;nstallation, as a roadway 'bridge over a railroad, a three foot cover would require too steep a grade for vehicles crossing the bridge. By virtue of ~he stifferling and load dis~ribu~ing concrete slab, a cover of from between 15 and 18 inches was placed over ~he s tructure .
During construction~ the structure maintained its shape well and in service tests after comple~ion have shown that the structure has maintained its shape and ''~emonstrated adequate strength Eor the loads to which it is subjected.
Modifications may be made in the lnvention wlthout departing from th~ spirit of it.
stiffening members 22 and 23 are appropriately affixed to buttress means 20 and 21. If desired, the top arch portion 17 can be connected.to the stifening members 22 and 23 by bolts or other appropriate fastening means.
The embodiment of Figure 4 is also provided with the stifening and load distributing member of thP present invention~ indicated at ~4. For purposes oE an exemplary showing, the stifening and load distributin~ member 24 is illustrated as being a reinforcad concrete sl~b poured in place and d~rectly over sti~ning members 22 and 23 which extend therethrou~h. In thls way, the s~iEfenlng m2mbers serve as additional reinQr~man~ or the slab 2~ as well as reiaforcing and stabilizillg means for the ~op arc~
~ortion~ preventing ~agglng o -~he top arch portion dua t~
the s~atic load inharen~ ln the cons~ructlQn oE such long~span structures.
~s indica~e~ above, ~he stlE~ening and load distrubutlng member oE the presPnt invention need not take the form of a reinorced concrete slab. Figure S is a ragmentary cross sectional view oE top ~rch por.ion 4, similar to Figure 2. In this instance~ the slab 10 has ~een replaced by pairs o longitudinally extending angles 25-26 and 27-28. Angles 25~26 are located directly opposite each other on the top and bottom surfaces of the top arch portion 4, as shown. The same is true of angles ` 27-28. The angle palrs 25-26 and 27W28 are loca~ed in p~rallel spaced relationship and are substantially equally spaced to eit~er side of the centerline of ~he top arch portion 4. The angle pairs may be attached to the top arch portion 4 by a plurality of bolts (two of which are shown at 29 and 30), or by any other appropriate fastening means. The angle pairs 25~26 and 27-28 serv~ to align the corrugatlons of the adjacent liner plates andl together with that part of top arch portion 4 extending between the angle pairs, form an "I-beam" which serves substantially the same purposes as does slab 10 of Fi~ure 2. It would also be within the scope of the invention to provide angles 25 and 27 only or angles 26 and 28 only, depending upon the span of the liner. For longer span structures the provision of pairs of angles ~5-26 and 27-28 is preferred.
~igures 6 through 10 illustrate varlous types of longitudinal extending load spreading means which may be substituted or buttresses 7 and 8 in Figures l and 3. In Figure 6 liner 1 is shown ragmentarily, made up of retain~ng wall portion 2 and ~op arch portion ~. In ~his Figure buttress me~ns 7 has h~en replaced by a longitudinally extanding ang.le 31~ The lower leg o~ angle 31 ls a.~ixed ~o li~er 1 by an~ appropria~e means such as bol~s~ on~ o w~ich is shown at 32. ~hat leg o angle 31 abuttlng liner 1 may be sli~htly curved ~o conform to the 3U liner, i;E d~sired.
In Flgure 7 like parts hava baen given like index numerals and buttress means 7 has been replaced by a longitudinally extending T-beam 33 affixed to liner l by bolts or o~her appropriate means (not shown).
In Flgure 8 ~as in Eigures 9 and lO to be described hereina~ter) like p~rts have again been given like index 2~)~
, numerals. In this instance buttress means 7 has been replaced by a plurality of longitudinally extending, transversely curved corrugated me~al plates (two oE which ~re shown at 34 and 35) joined ~ogether by bolts ~one of which is shown at 36) and joined to the liner 1 by additional bolts (two of which are shown a~ 37 and 38).
The structure of Figure 8 may be filled with concrete or other consolidated material, if desired.
Figur~ 9 illustrates an H-beam 39 as a replacement ~or b1~ttress means 7. The H-beam 39 is af~ixed to liner 1 by a plurality of bolts (two of which are shown at 40 and 41) or other fastening means.
In Figure 10, buttress means 7 has been replaced by one or more longitudinally extending corrugated metalllc plates 42 connected to liner 1 by bolts 43 ~or other appropriats fastening means) lcca~ed along the longitudin~l edges and valleys of the plate 42.
EXAMPI.E
A composite arch structure o~ the type shown in Figures 1 through 3 was constructed. The liner was made of 1 gauge corrugated steel plates having a high arch profile~ a maximum span of 33 feet 1 inch and a height ~bove the ooters o 21 feet 6 inches. Buttresses of the type shown at 7 and 8 were provided~ and the stiEfening and load distributing member 10 constituted a reinEorced concrete member pourad at sub~-tantiall~ the same ~ime as tha but~ress means 7 and 8 were poured. The concre~e slab 10 was shear connec~ed to ~he ~op arch portion oE the struc~ure by w~lded shear conn~e~ors spaced on 24 inch centars along both the width and length o~ the concre~e slab. The concrete slab was 8 Eeet wida and 12 inches thick at the topmost portion of the top arch sec~ion. The slab extended subs~antially the entire length of the topmost part of the top arch portion, i.e., 32 feet. The bottom`center line length of the liner was 92 feet and the , top center line length thereof was 52 feet.
The AASHTO standard specifications call for a minimum cover or this type of structure of 3 feet. In the particular ;nstallation, as a roadway 'bridge over a railroad, a three foot cover would require too steep a grade for vehicles crossing the bridge. By virtue of ~he stifferling and load dis~ribu~ing concrete slab, a cover of from between 15 and 18 inches was placed over ~he s tructure .
During construction~ the structure maintained its shape well and in service tests after comple~ion have shown that the structure has maintained its shape and ''~emonstrated adequate strength Eor the loads to which it is subjected.
Modifications may be made in the lnvention wlthout departing from th~ spirit of it.
Claims (20)
1. A composite arch structure of the type comprising an elongated, relatively thin gauge liner with compacted backfill thereabout, said liner comprising first and second flexible retaining wall portions and a flexible top arch portion extending therebetween, said first and second retaining walls having longitudinally extending upper edges, said top arch portion having longitudinally extending lateral edges affixed respectively to said upper edges of said first and second retaining wall portions, characterized by a stiffening and load distributing member structurally connected to said top arch portion and extending centrally and longitudinally of said top arch portion for the majority at least of the length thereof.
2. Composite arch according to claim 1, characterized in that said stiffening and load distributing member comprises a reinforced concrete slab affixed to the upper surface of said top arch portion.
3. Composite arch according to claim 1, characterized by first and second pairs of angles, said angles of said pairs extending longitudinally of and substantially the length of said top arch portion, said angles of said first pair being located respectively above and below said top arch portion directly opposite each other, said angles of said second pair being located respectively above and below said top arch portion directly opposite each other, said first and second pairs of angles being affixed to said top arch portion directly opposite each other, said first and second pairs of angles being affixed to said top arch portion in parallel spaced relationship to either side of the centerline of said top arch portion, and substantially equidistant from said centerline, said first and second pairs of angles and that part of said top arch portion extending between said first and second angle pairs comprising said stiffening and load distributing member.
4. Composite arch according to claim 1, characterized by first and second angles extending longitudinally of and substantially the length of said top arch portion, said first and second angles being affixed to the upper surface of said top arch portion in parallel spaced relationship to either side of the centerline of said top arch portion and substantially equidistant from said centerline, said first and second angles and that part of said top arch portion extending therebetween comprising said stiffening and load distributing member.
5. Composite arch according to claim 1, characterized by first and second Angles extending longitudinally of and substantially the length of said top arch portion, said first and second angles being affixed to the lower surface of said top arch portion in parallel spaced relationship to either side of the centerline of said top arch portion and substantially equidistant from said centerline, said first and second angles and that part of said top arch portion extending therebetween comprising said stiffening and load distributing member.
6. Composite arch according to claim 1, characterized by a pair of load spreading means comprising elongated bodies extending longitudinally of said liner, said load spreading means being affixed to the exterior of said liner on either side of the vertical axis thereof at positions where a radial force acting on said liner forms an angle of about 45° or more to the horizontal.
7. Composite arch according to claim 6, characterized in that said load spreading means comprises an elongated concrete body.
8. Composite arch according to claim 6, characterized in that each of said load spreading means comprises an elongated angle member.
9. Composite arch according to claim 6, characterized in that each of said load spreading means comprises an elongated T-beam.
10. Composite arch according to claim 6, characterized in that each of said load spreading means comprises an elongated H-beam.
11. Composite arch according to claim 6, characterized in that each of said load spreading means comprises at least one pair of elongated, transversely curved, corrugated metallic plates joined together at one of their longitudinal edges and affixed to said liner at the other of their longitudinal edges, forming an inverted V-shaped member affixed to said liner.
12. Composite arch according to claim 6, characterized in that each of said load spreading means comprises at least one elongated transversely corrugated metallic plate affixed to said liner.
13. Composite arch according to claim 6, characterized by plurality of arcuate stiffening members, each of said stiffening members having its ends affixed to said pair of load spreading means and overspanning said top arch portion, said top arch portion being affixed to said arcuate stiffening members.
14. Composite arch according to claim 13, characterized in that said stiffening and load distributing member comprises a reinforced concrete slab cast in situ, said arcuate stiffening members passing therethrough.
15. A method of constructing a composite arch structure of the type comprising an enlogated relatively thin gauge liner with compacted backfill thereabout, said liner comprising a pair of flexible retaining wall portions connected at their upper longitudinal edges to a top arch portion extending therebetween, comprising the steps of assembling said liner in situ, backfilling and compacting backfill material against the exterior surface of both sides of said liner to positions thereon where a radial force on said liner forms an angle of about 45° or more to the horizontal, characterized by structurally connecting to said top arch portion of said liner an elongated stiffening and load distributing member, locating said stiffening and load distributing member longitudinally and centrally of said top arch portion, and continuing backfilling and compacting backfill material to cover said liner and said stiffening and load distributing member.
16. The method according to claim 15, characterized in that stiffening and load distributing member comprises a reinforced concrete slab.
17. The method according to claim 16, characterized by the step of casting said slab in situ.
18. The method according to claim 16, characterized by the step of pre-casting said slab.
19. A method of constructing a composite arch structure of the type comprising an elongagted relatively thin gauge liner with compacted backfill thereabout, said liner comprising a pair of flexible retaining wall portions connected at their upper longitudinal edges to a top arch portion extending therebetween, comprising the steps of assembling said liner in situ, characterized by structurally connecting to said top arch portion of said liner an elongated stiffening and load distributing member longitudinally and centrally of said top arch structure and backfilling and compacting backfill material about said liner and said stiffening and load distributing member.
20. The method according to claim 19, characterized in that said stiffening and load distributing member comprises a reinforced concrete slab.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410729A CA1180200A (en) | 1982-09-03 | 1982-09-03 | Composite arch structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000410729A CA1180200A (en) | 1982-09-03 | 1982-09-03 | Composite arch structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180200A true CA1180200A (en) | 1985-01-02 |
Family
ID=4123524
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000410729A Expired CA1180200A (en) | 1982-09-03 | 1982-09-03 | Composite arch structure |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1180200A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111255488A (en) * | 2020-03-18 | 2020-06-09 | 福建工程学院 | High-strength corrugated plate structure and method for tunnel reinforcement |
-
1982
- 1982-09-03 CA CA000410729A patent/CA1180200A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111255488A (en) * | 2020-03-18 | 2020-06-09 | 福建工程学院 | High-strength corrugated plate structure and method for tunnel reinforcement |
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