Seismic cracking mechanism and control for pre-stressed concrete box girders of continuous rigid-frame bridges: Miaoziping bridge in Wenchuan earthquake as an example

Abstract The box girder of the Miaoziping Bridge, a three-span prestressed concrete continuous rigid-frame bridge, suffered serious crack in its section’s web near 1/6 to 1/2 length side span and middle-span 1/4 3/4, as result 2008 Wenchuan earthquake, which also caused large lateral residual displacements at both ends span. In this study, eight strong-motion records bridge site two other (El Centro Taft) are selected inputs for time-history analysis bridge. cantilever construction process initial stress considered model seismic numerical simulation. Further, simulation results compared with actual earthquake damage. cracking mechanism, influencing factors control damage discussed. high-stress zones agree observed, even various considered. findings reveal that maximum (principal) tensile exceeds strength under excitations, cracks occur. Under input directions ground motions, proportion main stresses induced by shows differences. After failure shear keys transverse direction decrease mid-span. However, beams spans revealed displacements. Considering uplift beam ends, axial torque girder’s greatly reduced. Setting bi-directional friction pendulum bearings on transition pier is an effective damping measure mid-span drifts ends.