US2339925A

US2339925A - Suspension bridge

Info

Publication number: US2339925A
Application number: US228204A
Authority: US
Inventors: Haupt Wilhelm
Original assignee: Individual
Current assignee: Individual
Priority date: 1937-09-24
Filing date: 1938-09-02
Publication date: 1944-01-25
Anticipated expiration: 1961-01-25

Description

Jan. 25, 1944. w. HAUPT I 2,339,925

SUSPENSION BRIDGE Filed Sept. 2. 1938 Patented Jan. 25, 1944 SUSPENSION BRIDGE Wilhelm Haupt, Dort mund-Hoerde, Germany;

vested in the Alien Property Custodian Application September 2,

1 Claim.

In patent application Serial No. 126,471, of February 18, 1937, protection is claimed for bridge supporting structures which in the space between two roadways have a torsion-resisting foot pro- J'ecting beyond these roadways and which is capable by its torsional strength of taking up the overturning moments imparted by one-sided traffic load. In this patent application a supporting structure for suspension bridges is described, in which the torsion-resisting foot is formed by a torsion-proof stiffening supporting structure. It is absolutely essential, that the stifiening supporting structure is made proof against torsion because the overturning moments occurring in the case of one-sided traiiic loading would not otherwise be taken up.

In the suspension bridges hitherto generally known with at least two suspension rod supporting walls between which the main track is arranged, a torsion-proof construction of the stillening supporting structure is not essential because, in the case of one-sided trafiic loading, one of the suspension rod supporting walls is merely loaded slightly more than the other suspension rod supporting wall, with the result that the overturning moment is taken up.

However, in this mode of construction the objectionable fact became apparent that the roadway under one-sided tramc loading inclines to a considerable extent in the transverse direction, this transverse inclination attaining under certain circumstances for example the value of 1:30 or even more. It is obvious that such a steep transverse inclination means very great technical disadvantages for high speed traffic, for example high speed electric railways and the like. The extent of this transverse inclination can be considerably reduced if the stiifening supporting structure is made proof against torsion. It is known, that the deformations of a torsion-proof hollow body are exceptionally slight as compared with the saggings of a cable. Therefore, by the torsion-proof construction of the stifiening supporting structure it is possible to attain a transverse inclination of the bridge under one-sided traffic load of only a fraction of the value which occurs when the stiffening supporting structure is not made proof against torsion. The greater the torsional strength of the stifiening supporting structure is made, the more will the one-sided trafiic load be relieved on the nearest suspension rods supporting wall and the opposite suspension rods supporting wall is utilized for taking up the vertical load. In the optimum case the stilfening supporting structure can be made of such 1938, Serial No. 228,204

In Germany September 24, 1937 great torsional strength that, if one supporting cable is entirely destroyed, it takes up entirely the strong overturning moments then produced by the continual load. The advantage is enormous, especially in case of war, as, even in the event of a Whole cable being destroyed, the bridge does not collapse (with the result that under certain circumstance the road running under the bridge might also be blocked), but is still capable of allowing trafiic even if on a restricted scale.

The torsional strength of the stiffening sup-.

porting structure ways, for example:

(1) By connecting the upper and lower flanges of each of two vertical stiffening girders by a horizontal connection, it being evident that such a horizontal connection may consist of a solid plate or of a still roadway plate,

(2) Where the stiffening supporting structure consists of a three-flange girder or of a tube. As it is known, that the tube cross-section is the most favorable cross-section for taking up torsional stresses, the be relatively small and the tube itself can, if desired, be used directly as conduit for gas, water or other fluid.

The advantages of a torsion-proof stifiening supporting structure may be ensured even for a supporting structure partly destroyed by bombs, if instead of two vertical stiifening girders more than two such girders are arranged whose upper and lower ribs are connected by horizontal connections. If in such a stiffening supporting structure one or several stiifening girders is or are destroyed by bombs the remaining girders recan be attained in various main torsion-proof with their horizontal con nections and are still capable of appreciable extent the transverse inclination of the roadway under one-sided trafiic loading.

Referring to the drawing for a more complete disclosure:

Fig. 1 is a diagrammatic transverse view and Fig. 2 is a diagrammatic longitudinal view of a suspension bridge embodying my invention.

The bridge is suspended from two supporting cables I by means of rods or cables 2. The stiffening supporting structure below the roadway or track 3 is formed by the vertical transverse stillening girders 4, arranged at various distances apart and may be constructed as plate girders or as framework girders. On each side of the main track 3 a footway or auxiliary roadway 5 may be provided.

The torsion proof stiffening supporting structure comprises a torsion-prooftube 6 to which reducing to an diameter of this tube can the transverse girders 4 are rigidly secured, the below said roadway rigidly connected with the supporting structure being in turn rigidly conabutments against twisting for taking up the nected with the abutments I The tube 6 is 10- tilting moments occasioned by one-sided loadings cated substantially in the center of the bridge on said roadway, said torsion-proof structure and extends longitudinally the entire length of 5 comprising a. tubular member substantially in the bridge. the center of said bridge and extending longitu- I claim: dinally for the entire length of the latter, and In a suspension bridge having at least two a series of transverse girders rigidly secured to rows ofsuspension rods, a main roadway arsaid tubular member.

ranged between said rows of suspension rods, and 10 WILHELM HAUPT.

a torsion-proof stifiening supporting structure