US3027687A

US3027687A - Bridge construction

Info

Publication number: US3027687A
Application number: US753456A
Authority: US
Inventors: Giorgio A Baroni
Original assignee: Reynolds Metals Co
Current assignee: Reynolds Metals Co
Priority date: 1958-08-06
Filing date: 1958-08-06
Publication date: 1962-04-03
Anticipated expiration: 1979-04-03

Description

April 3, 1962 G. A. BARoNl BRIDGE: CONSTRUCTION 4 Sheets-Sheet 1 Filed Aug, 6, 1958 maman INV ENTOR.

GIORGIO A. BARONI TTORNEYS.

April 3, 1962 G. A. BARONI BRIDGE CONSTRUCTION 4 Sheets-Sheet 2 INVENTOR.

GIORGIO A. BARON! lFil Filed Aug. 6, 1958 O O o D 0 April 3, 1962 G. A. BARON! BRIDGE CONSTRUCTION 4 Sheets-Sheet I5 Filed Aug. 6, 1958 INVENTOR.

GIORGIO A. BARON! ATTORNEYS;

April 3, 1962 G. A. BARONI 3,027,687

BRIDGE CONSTRUCTION Filed Aug. 6, 1958 4 Sheets-Sheet 4 INVENTOR.

GIORGIO A. BARON! United States Patent f 3,027,637 BRIDGE CONSTRUCTION Giorgio A. Baroni, New York, N.Y., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed Ang. 6, 1958, Ser. No. 753,456 6 Claims. (Cl. 541-290) The invention relates to bridge construction, bridge beam components and a prefabricated modular system for rapid erection of lightweight bridges especially adapted to highway and public road building.

Progressive highway and public road experts have long desired a lightweight bridge which could be easily fabricated and transpolted to the bridge site, speedily erected and which would be practically free of maintenance needs. I have invented a bridge which will more adequately satisfy these objectives than will any other practical construction heretofore available to highway engineers.

My bridge construction includes a lbeam of inverted ,channel form having a series of shear connectors spaced along the top of the beam to key the beam directly to a concrete roadway and the like as a compression chord of the composite structure, `and having strengthened bottom edges to form tension chords. The beam has curved sides which resist buckling even when made of thin sheet metal such as aluminum. By special formation of the beam with high strength tension chords at its bottom edges and with a relatively light upper portion, I have devised what may perhaps be most simply described as a tension-biased beam component. Then by providing effective shear connector means along the top of this special beam component to key the top of the channel to a concrete roadway and the like, the material of the roadway constitutes a substantial element of the compression chord comprised by the composite channel and roadway structure and tends to compensate for the initial tension bias of the beam component. By this means more effective use is made of the high tensile kstrength properties of the lower chords of the beam component as constituted, for example, by special aluminum extrusions at the bottom edges of the channel, while the upper portion of the beam can be made quite light instead of being designed as a conventional compression chord. This feature may be more clearly understood by thinking of a conventional highway bridge construction using ordinary I-beams in which the cross section of the beam is such as to provide a balanced moment of inertia about its neutral axis as distinguished from my tension-biased construction which, once effectively keyed to the material of the roadway, will afford greater strength per unit weight of the beam component. Thus the material of the beam is used more effectively so that the bridge can be lighter in weight and its components more readilytransported to the erection site.

In my preferred construction, flanged diaphragms are secured transversely within the beams and other flanged diaphragms aresecured transversely between the beams. Permanent forms are ,provided `for the concrete roadway by deck sections extending between the upper parts of the beams and resting on the transverse diaphragms. Also,' in mypreferred construction these deck sectionsgare constructed of corrugated aluminum arranged with the corrugations parallel to the beam component, or substantially so. In the combined structure the material of the roadway and the aluminum deck sections as bonded together, and the material of the roadway as keyed to the tops of the channels, constitute substantial elements of the compression chord comprised by the metal channel, deck and roadway structure. To the extent that this particular interrelationship of the channel, deck and roadway structure compensates for the initial tension bias of 3,@2787 Patented Apr. 3, 1962 the beam components, an improvement is achieved over bridge constructions utilizing conventional beams and over any other bridge construction where the compression strength of the road material is not utilized through redistribution of the beam material in a manner to yield a more effective weight-strength ratio in the composite structure. An optimum weight-strength ratio is considered to be the most important single objective ofI economical highway bridge construction.

Another aspect of my invention provides a prefabricated beam construction comprising beams of inverted channel form having a series of shear connectors spaced along the length of the top of the beams, the beams being nestable in their complete prefabrica'ted form. Flanged diaphragms attachable transversely within and between the beams also are nestable in their complete prefabricated form. The assembled parts leave the shear connectors projecting above the tops of the diaphragms to key the beams to the material of the roadway.

With reference to the drawings, I shall now describe the best mode contemplated by me for carrying out my invention.

FIG. l is a perspective view of a bridge construction according to my invention. Portions of the roadway and beams are broken away to reveal hidden construction.

FIG. 2 is a side elevational view of the same bridge, with the roadway and intermediate portions of the span omitted.

FIG. 3 is an end elevational view of the same.

FG. 4 is a detail view similar in aspect to FIG. 3 but showing a modified construction.

FIG. 5 shows how the beams nest.

FIG. 6 shows how the diaphragms nest.

FIG. 7 shows how the bottom edges of adjacent beams are connected together. In this transverse section we see the form of the special extruded tension chords of the beams.

FIG. 8 is a perspective view of one of the transverse shear connectors welded to the top of :a beam.

Referring to FIGS. 1-3, we see bridge beams 9 of inverted channel form having a series of shear connectors 10 spaced along the length of the top of each beam to key it directly to a concrete roadway 11 and the like as a compression chord of the composite structure, and having strengthened bottom edges 12 to form tension chords. The bottom edges 12 are conveniently made as aluminum extrusions of the special form shown in FIG. 7, welded to the curved sheet metal sides 13 of the beam. The shear connectors, FIG. 8, also conveniently made as aluminum extrusions, include attaching flanges 14, upwardly projecting webs 15 extending transversely of the beam, iand horizontal vflanges 16 at the tops of the webs. Webs 15 are of increasing thickness toward their bases compatible with the diagram of horizontal shear.

Flanged diaphragms 17, which may, if desired, be made with one or more center openings for lightness and to receive pipe lines or other facilities, are secured transversely within the channels of the beams, as by means of blind rivets, Huck fasteners, or otherwise. Other

flanged diaphragms

18 and 19 are secured in a similar manner between the beams and at the outsides thereof. Corrugated aluminum deck sections 20 are assembled in positions between the upper parts of the beams and resting on the tops of diaphragms 1S with shear connectors 10 exposed to key the beams directly to the roadway 11. The material of theroadway and the deck sections 2i] as bonded together, and the material of the roadway as keyed to the tops of the beams 9, constitute substantial elements of the compression chord comprised by the composite metal channel, deck and roadway structure. Having regard to this, I build the tension portions of my beams 3 heavier than the compression portions thereof, creating the tension bias of which I have spoken. Thus it becomes possible to take substantial advantage of the compression-keyed construction of the composite structure, and, through a corresponding reduction in weight of the beams, to gain an improved weight-strength ratio.

As shown in FIGS. 1 and 2, the diaphragms are spaced progressively closer together toward the ends of the span. This spacing preferably is related to the shear diagram for maximum support toward the ends where shear loading is the greatest.

FIGS. 5 and 6 show how the beams and diaphragme, respectively, can be nested together in their complete prefabricated forms. In the case of channel diaphragms 17 this is made possible by the parabolic shape of the tlanged edges of the diaphragms. In the case of the intermediate diaphragms 18 nesting is made possible by turning the curved side -ilanges one way and the straight top anges the other. Thus the several components can be completely fabricated in the shop, nested compactly for shipment to the bridge site and speedily assembled with the use of conventional field equipment such as wrenches and blind rivet guns. All special metal forming and/ or weld ing operations having been'performed on the prefabricated components, the bridges can be assembled on location in a matter of hours or days instead of the days or weeks formerly required with conventional girder construction. No temporary supports of the beams are necessary during erection or during molding of the concrete deck, as the beams are designed to take the erection deadload with minimum deflection yand stresses.

Prefabrication may be advanced another step to include attachment of beam diaphragms in the shop. To accomplish this the intermediate diaphragms are made in two pieces 21 and 22, FIG. 4. Thus the prefabricated beam construction includes diaphragms 17 secured transversely within the channel of the beam and other diaphragms secured in positions projecting transversely from opposite sides of the beam and adapted to be connected at the bridge site to the transversely projecting diaphragrns of .another prefabricated beam of like construction, as by means of fastenings 23 where the mating diaphragms come together. This alternate construction will still further reduce the time required for erection while nevertheless holding the prefabricated components to a size which can be easily transported and handled.

The terms and expressions which I have employed are used in a descriptive yand not a limiting sense, and I have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the purview'of the claims.

I claim:

1. A prefabricated beam construction for bridges, comprising -beams of inverted channel form having a series of shear connectors spaced along the length of the top of the beams, said beams being nestable in their complete prefabricated form, transverse diaphragms attachable within the channels of the beams, other transverse diaphragms attachable between the beams, and deck sections for assembly in positions between the upper parts of the beams and resting on said other transverse diaphragms with said shear connectors exposed to key the beams directly to a concrete roadway and the like.

12. A prefabricated beam construction for bridges, comprising beams of inverted channel form having a series of shear connectors spaced along the length of the top of the beams, said beams being nestable in their complete prefabricated form, anged diaphragms attachable transversely within the channels of the beams, and other anged diaphragms attachable transversely between the beams, said flanged diaphragrns being nestable in their complete prefabricated form, and said other flanged diaphragms likewise being so nestable.

3. Prefabricated nestable beams and nestable diaphragms to go transversely within and lbetween the beams, said nestable beams in their prefabricated form including shear connectors spaced along the length of the top of the beams, and said nestable diaphragms in their prefabricated form comprising attaching flanges to secure them to the beams, the assembled parts leaving said shear connectors projecting above the tops of 'the diaphragms to key the beams directly to a concrete road- -way and the like.

4. A Aprefabricated beam construction for bridges, comprising va beam of inverted channel form having a series of shear connectors spaced along the length of the top Vof the beam, diaphragms secured transversely within the channel of the beam and other diaphragms secured in positions projecting transversely from opposite sides of the beam and adapted to be connected .at the bridge site to the transversely projecting diaphragms of another prefabricated beam of like construction.

5. A prefabricated beam construction for bridges, comprising a beam of inverted channel form, diaphragms secured transversely within `the channel ,of the beam and other diaphragms secured in positions projecting transversely from opposite sides of the beam and `adapted to be connected at the bridge site to the transversely projectingdiaphragms of another prefabricated beam of like construction. f

6. .A prefabricated beam construction for bridges, comprising lightweight tension-biased bridge beam cornponents consisting essentially of an inverted laluminum channel having strengthened bottom edges to form high strength tension chords and having relatively light upper portions ywhich along the length ofthe tops of the channels are provided with effective shear connector means to key the tops of the channels to a concrete roadway and the like, and `corrugated aluminum deck sections for assembly `in positions between the upper parts of the beam components with the corrugations thereof vsubstantially -parallel tothe beam components, by virtueof all of which the material of the roadway and the valuminum deck sections as bonded together, and the material of the roadway as keyed to the tops of the channels, constitute substantial elementsof the compression chord comprised by the composite metal channel, deck and roadway structure, and tend to compensate for the initial tension bias of the beam components.

References Cited in the tile of this patent UNITED STATES PATENTS 494,157.6 Lewis Apr. 4, 1893 602,274 Sill Apr. l2, 1898 1,079,045 Hammett Nov. 18, 1913 1,380,613 Wall June 7, 1921 2,096,921 Sahlberg Oct. 26, 1937 2,731,824 Hadley Jan. 24, 1956 FOREIGN PATENTS 560,336 GreatBritain Mar. 30, 1944 v811,033 Germany Aug. 16, 1951