Research Of Seismic Behavior For Concrete-Filled Steel Tube Laced Column High-Pier And Long-Span Continuous Rigid-Frame Bridge

Concrete-filled steel tube (CFST) laced column is becoming a new structure type of bridge pier. Due to its excellent mechanical properties, CFST laced column has been applied to high-pier of long-span continuous rigid-frame bridge. At present, Heishigou grand bridge and Labajin grand bridge, which are located at active seismic zone, have used this new type pier over100m high. If the bridges were damaged in earthquake, it would be very difficult to restore transport because of the specific landform environment. Moreover, the earthquake relief work will be severely affected and the losses caused by the secondary disaster of earthquake will be greatly increased. Therefore, it is necessary to carry out a research on bending properties of CFST laced column and it is significant to evaluate seismic behavior of CFST laced column high-pier and long-span continuous rigid-frame bridge.This thesis takes Heishigou grand bridge as engineering background. Evaluation, according to the code, of the seismic behavior of CFST laced column high-pier and long-span continuous rigid-frame bridge are made by using method with the combination of test research and analysis calculation. The main work is as follows:1) To research bending properties of CFST laced column, bending failure test and whole process simulation by finite element program ANSYS are carried out on the scale model of the high pier of Heishigou grand bridge.2) Seismic response analysis of main bridge is performed by finite element program MIDAS.3) Maximum displacement of pier top and axial force-moment-curvature curves of pier bottom are calculated by nonlinear analysis of main piers.4) According to the code of Guidelines for Seismic Design of Highway Bridges, the seismic behavior of CFST laced column high-pier and long-span continuous rigid-framed bridge is evaluated.Results show that CFST laced column with ductile failure in the test have a good plastic deformation ability. The finite element method used in this paper is a relatively accurate method to calculate the ultimate flexural load carrying capacity of CFST laced column. The ratio of displacement of pier top to pier height is less than2/1000under E1earthquake action, which is less than4/1000under E2earthquake action. Attention should be paid on the pier with lower height which is more likely damaged in the earthquake because of its larger internal force and smaller section size. Since the checking results of main piers under both E1and E2earthquake actions meet requirements of code, the main bridge has good seismic behavior.