Lightweight modular, truss-deck bridge system

A modular bridge for placement between spaced apart supports comprising:

• a plurality of side-by-side truss-deck modules, each module having spaced apart upper and lower chord plates and intermediate, chord plate connecting web means, the web means having a width substantially equal to the width of the upper chord plate, the upper chord plate simultaneously defining a deck for supporting vehicular traffic;
• load distributing beams having a length substantially equal to the combined width of the modules, the beams being disposed intermediate points of attachment between the upper chord plates and the web means, the beams having a relative stiffness when subjected to vehicular loads in a transverse bridge direction which exceeds the stiffness of the upper chord plate in that direction;
• and means for rigidly securing the load distributing beams to an underside of the chord plate only;
• whereby the beams in connection with the web members distribute vehicular loads in a transverse bridge direction over a substantial width of the bridge to reduce the stress induced by the vehicular load on the upper chord plate.

A lightweight, high efficiency modular bridge constructed of a plurality of pre-assembled bridge modules, the bridge comprising:

• a plurality of longitudinally extending side-by-side modules, each module having spaced apart upper and lower chord plates, at least the upper chord plate being constructed of corrugated plate;
• a plurality of chord plate connecting diagonal web members arranged over the length of the chord plates, the web members being constructed of corrugated plate;
• means for attaching the web members to the chord plates, the attaching means securing the web members to the chord plates over substantially the full width thereof so as to intermittently support the upper chord plate with the web members over its substantially full width;
• and lateral load distributing means connected to an underside of the upper chord plate at locations about midway between adjacent attaching means for the web members for distributing vehicular loads at such midway locations over an extended lateral width of the upper chord plate, the load distributing means including a load distributing rib having a moment of inertia ##EQU2## k = a constant in the range of between about 2 to 120;
• I.sub.1 = the average moment of inertia of the corrugated upper chord plate per inch width (in in.sup.4);
• S.sub.1 = the spacing between adjacent web member attaching means (in inches);
• S = the spread of a vehicular load over a given width of the upper chord plate (in inches) due to the effective height of the upper chord plate and the width of vehicle wheels;
• and means for securing the ribs to the underside of the upper chord plate.

A lightweight, high efficiency module for constructing a modular bridge by arranging a plurality of pre-assembled bridge modules side-by-side, the module comprising:

• spaced apart upper and lower chord plates, at least the upper chord plate being constructed of corrugated plate;
• a plurality of chord plate connecting diagonal web members arranged over the length of the chord plates, the web members being constructed of corrugated plate;
• means for attaching the web members to the chord plate, the attaching means securing the web members to the chord plates over substantially the full width thereof so as to intermittently support the upper chord plate with the web members over its substantially full width;
• and lateral load distributing means for connection to an underside of the upper chord plate at locations about midway between adjacent attaching means for the web members for distributing vehicular loads at such midway locations over an extended lateral width of the upper chord plate and for securing the modules to each other when placed side-by-side, the load distributing means including a load distributing rib having a moment of inertia ##EQU3## k = a constant which is a factor of (L'/L) . (S/12);
• L = the vehicular wheel load (in lbs.);
• L' = (l/sw) (in lbs./ft. width of the upper chord plate);
• Sw = the lateral bridge width over which L is to be distributed (in ft.);
• I.sub.1 = the average moment of inertia of the corrugated upper chord plate per unit width (in in.sup.4);
• S.sub.1 = the spacing between adjacent web member attaching means (in inches);
• S = the spread of a vehicular load over a given width of the upper chord plate (in inches) due to the effective height of the upper chord plate and the width of vehicle wheels;
• and means for securing the ribs to the underside of the upper chord plate only.

A method for erecting a relatively lightweight slab-type bridge truss-deck comprising the steps of forming an upper chord plate having a width and a length sufficient for placement of the plate between bridge supports, the upper chord plate having longitudinally extending corrugations;

• forming a lower chord plate having a width and a length substantially equal to that of the upper chord plate;
• forming a plurality of webs from corrugated sheet metal having a given corrugation pitch and depth, the web having a center section and at least one integrally constructed crest section protruding from an end of the center section, angularly inclining the crest sections relative to the center section by incrementally curving a portion of the web from a point spaced from an end of the end section towards the center section about an axis that is perpendicular to the corrugations of the web by furnishing a pair of opposing, complementary concave and convex forming dies having a profile corresponding to the corrugations of the web, the dies having a curved length with a curvature radius corresponding to the desired curvature radius of the curved portion between the crest section and the center section, the curved length extending over an arc which is substantially less than the desired arc length of the curved portion, placing the web between the dies so that only part of the curved portion is disposed between the dies, thereafter forcing the dies against each other to thereby flow-form the curvature in the curved portion, moving the dies apart, advancing the web in a direction parallel to the corrugations by a distance no greater than the curved die length, thereafter repeating the steps of forcing the dies against each other, moving the dies apart, and advancing the web parallel to the corrugations a sufficient number of times until the desired full arc length has been formed in the web;
• placing a plurality of webs end to end between the upper and lower chord plates so that the crown sections contact the chord plate and the corrugations of the webs and of the chord plates are in mutual alignment;
• securing the respective crown sections to the chord plates to thereby form the slab section having an undulating, diagonally oriented web support between the chord plates;
• thereafter placing a number of slab sections onto the bridge support so that the bridge has the desired overall width as defined by the combined width of all slab sections;
• and securing the sections to each other and to the bridge supports.

A lightweight high efficiency modular bridge constructed of a plurality of pre-assembled bridge modules, the bridge comprising:

• a plurality of longitudinally extending, side-by-side modules, each module having a width less than about 48 inches, spaced apart upper and lower chord plates, and a chord plate connecting sinusoidal support structure alternatingly connected to the upper and the lower chord plates, the support structure having a web-like configuration defined by serially arranged center sections and upper and lower crown portions connected with the center sections, the support structure further having a width substantially equal to the width of the chord plates;
• means for fastening the crown portions to the chord plates over substantially their full width;
• the chord plates and the support being constructed of corrugated metal plate defining longitudinally running corrugations, the corrugations of the chord plates and of the support nesting in each other, the corrugations further having a trapezoidal cross-section, a corrugation depth of at least about 51/2 inches and a corrugation pitch larger than the corrugation depth;
• load distribution ribs positioned intermediate fastening points between the crown portions and the upper chord plate, being oriented perpendicular to the upper chord plate corrugations, and having a width so as to contact all modules of the bridge;
• means for rigidly securing the load distribution ribs to the upper chord plates only;
• the load distribution ribs having a section modulus which is sufficiently large so that vehicular point loads applied to the upper chord plate in the vicinity of a load distribution rib are transferred by the load distribution rib onto the upper chord plates of the bridge over a width of several feet so as to cause a more even distribution of the vehicular point load on the upper chord plates and thereby reduce the stressing thereof;
• a plurality of spaced apart upright posts located proximate lateral sides of the outermost modules of the bridge;
• means rigidly connecting the posts with each of the upper and the lower chord plates so that a portion of the post protrudes above the upper chord plate;
• a guard rail extending over the length of the bridge and secured to the protruding portions of the upright posts to define lateral safety barriers for the bridge;
• and a road bed placed on top of the upper chord plate to define a surface on which vehicular traffic can move.

A method for erecting a relatively low cost, lightweight modular bridge comprising the steps of:

• forming from flat sheet corrugated plate of a unitary width;
• forming from the plate at least an upper chord plate and a plurality of diagonal webs;
• forming a lower chord plate;
• alternatingly attaching the diagonal webs to the upper chord plate and to the lower chord plate so as to assemble finished bridge modules;
• placing the finished modules side-by-side onto spaced apart supports at a site for the bridge, whereby the combined width of the upper chord plates of the modules defines the overall width of the bridge;
• interconnecting the modules to prevent relative lateral movements of the modules;
• and applying a road bed onto the upper chord plate to thereby finish the bridge;
• whereby the upper chord plate simultaneously forms the load bearing member of a truss and the traffic carrying deck of the bridge.