The Seismic Capacity Evaluation Of Long-Span Concrete Filled Steel Tubular Arch Bridges

In the past decades, The CFST arch bridge is being develoment rapidly in our country. These bridges are distributed in many areas including seismic zone in domestic. With the increase of the span, The seismic capacity evaulation of CFST arch bridge can not be ignored.Now, The research of the CFST arch bridges is focused on seismic response in performance, However, It is scarce about the seismic capacity assessment of CFST arch bridges. In this paper, Based on finite element software and some theory methods, According to two long span CFST arch bridge in guangxi(Longan Huazhou Bridge is a 129m CFST arch bridge and Nanning Yonghe Bridge is a 346m CFST arch bridge), The seismic capacity evaulation is researched. The main contents are as follows:1. Based on ABAQUS software,The CFST cross-section are analyzed under axial compression, bending and axial tension. And Further, The CFST cross-section are analyzed under complex stress state. Then the yield curve is drew up of CFST cross-section.2. Based on numerical simulation results, each yield stage is defined according to the yield process, and The cross-section formula of the bearing capacity is derived.Then combining the N-M curve and each yield stage, the curve of seismic capacity evaluation of arch rib curve is obtained. Thus evaluated the seismic capacity assessment of CFST arch rib. Finally, Taking Nanning Yonghe Bridge for example, its seismic capacity is assessed.3. According to the structural characteristics of CFST arch, failure modes of all parts such as arch rib, web member, horizontal contact, suspender, suspender beam and so on are determined.4. Based on the failure modes of all parts of CFST bridges, the earthquake damage criteria are studied, and the earthquake damage assessment models of all parts are built. The damage assessment indexes of all parts are calculated separately. Finally, the earthquake damage of the whole bridge is assessed.5. According to the research of earthquake damage assessment model, In this paper, the damage index are calculated according to introduce the combinatorial coefficient of the biggest axial force and moment, so the actual stress state is considered, making the damage assessment model more perfect and more reasonable.6. Taking Nanning Yonghe Bridge (that is a 346m CFST arch bridge) and Longan Huazhou Bridge (that is a 129m CFST arch bridge)for Example, the seismic capacity and earthquake damage of the members of each parts are analyzed, the results show that under the 10M earthquake action, the maximum damage index of three kinds of model with Nanning Yonghe Bridge is 0.329, the damage index of Longan Huazhou Bridge is 0.463, according to different extent of damage, The main component of concrete-filled steel tube arch bridge are in plastic. These bridge can use after reinforcement.