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Practical Method to Compute Lateral Load Distribution on Girder Bridge
Zhang Shi-duo
1984, 3(1):
35-45.
While the ratio between the width and the span of the girder bridge is less than 0.5(B/l≤0.5), lateral deflection curve under live load is assumed to be a straight line,then the eccentric compression method (rigid diaphragm method) is usually adopted in the calculation of load distribution on girder bridge. Further, if bending and torsion are coupling, a revised formula could be derived also. As has been proved theoretically and experimentally, the bending rigidity of diaphragms is for from absolute rigid, even under theratio of B/l≤0.5, the lateral deflection line is also curved, (Here, it is assumed to bein parabolic form.) Practically, T sections or unsymmetric I sections are often used in R.C. and P. C. girder bridges, torsional rigidities of these sections compared with bend ing can be neglected. In this paper, regardless the lateral position of live load across the bridge, the parabolic curve on lateral deflection is presumed. Applying the energy approach and principle of virtual work, a revised expression is finally reached to compute the lateral load distribution on girders. The author wishes that the derived expression can befunctioned not only for B/l≤0.5, but also extended to B/l≤1. in place of G. M, andrigid-slab method already in existence in bridge design.
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