Seismic Performance and Damage Control of Large-Span Prestressed Concrete Rigid-Frame Bridges with High Piers Crossing Strike-Slip Faults

Abstract

Post-earthquake surveys show that fault-crossing simply supported beam bridges or continuous beam bridges suffer from severe seismic damage, such as falling beams and even collapse. Currently, there is a lack of understanding of the seismic performance of fault-crossing prestressed concrete rigid-frame bridges (PCRFBs). In this study, a representative PCRFB was used as a case study, and typical strike-slip fault cases were discussed, including fault-crossing angles and permanent displacement. The results revealed that different from other bridge structure types, the mid-span section was prone to yield failure because of the significant plastic deformation demands when the fault crossed the middle span. Positive and negative moment failures of the mid-span girder occurred when the fault-crossing angle was greater than or less than 90°, respectively. The fault-crossing angle is an important factor that affects the seismic performance of PCRFBs. A value of 90° is a favorable fault-crossing angle with minimal damage. The deformation demands of the mid-span were larger than the internal force effects when there was an increase in the permanent ground displacement of the fault. The proposed shock-absorbing hinge system (SAHS) can effectively reduce the vertical displacement of the girder and can significantly avoid the occurrence of plastic hinges, so the main girder is protected.

Keywords: large-span rigid-frame bridge with high piers, strike-slip fault, fault-crossing bridge, fault-crossing angle, Seismic performance, permanent ground displacement, shock-absorbing hinge system (SAHS)