Study On Seismic Performance Of Composite Bridge Piers With Concrete Filled Steel Tubular Column Embedded Inside

Earthquake has occurred show that the phenomenon of bridge seismic damage is seriously, as an essential part of lifeline engineering, the bridge damage result in not only a huge direct economic loss, but also hamper the earthquake relief and reconstruction work for traffic disruption. Therefore, it is necessary to research on bridge seismic performance and guiding the seismic design.Girder bridge is the most commenly used bridge type in construction for it’s many advantages, such as high economic indicator, short construction period, etc., but it also the bridge type which injured most seriously in earthquake. The seismic performance of girder bridge depends on the key component—pier, whose serious damage may lead to falling beams, bridge collapse, and difficult to repair after earthquake. Therefore, how to improve the seismic performance of piers is one of the key issues in bridge seismic researching. On the basis of constant research and innovation, Prof. Qiu in Dalian University of Technology first proposed a new type of composite pier, which was formed by embedding concrete filled steel tubular (CFT) column in reinforced concrete (RC) pier, and the seismic performance of RC pier could be improved significantly.Engineering practice of the composite columns focus on the field of high-rise building, related research concentrate on the axial compression performance under static loads. Bridge structure has a different structure system, load type and force transmission mechanism compare to high-rise building, composite columns must have some distinctive performance characteristics as a component of bridge, but related research document is rare. The purpose of this paper is to deeply understand and grasp the seismic behavior of the new type composite piers, the main work and achievements are as follows:(1) Investigate the research findings on how to improve the seismic performance of pier, and propose embedding concrete filled steel tubular column into ordinary RC pier to improve the seismic performance of girder bridge;(2) The pseudo-static comparative test of composite columns was carried out, and seven factors (axial load index, stirrup ratio, longitudinal reinforcement ratio, steel tube diameter and length, concrete strength and shear span ratio) were taken into consideration, a detailed description of the experiment design, test procedure and damage develop of model specimens were given;(3) After the analysis of test data, a evaluate was done about the influence of factors described above affect on seismic performance indicators, such as ductility, strength, energy dissipation and residual displacements; (4) Based on numerical analysis software OpenSees platform, fiber element model were established to simulate quasi-static test process and a comparison was made between numerical result and test data;(5) By taken regression analysis of a considerable number of data, a formula for calculating the equivalent yield moment of composite pier was put forward, hope to provide useful reference for the seismic design of such piers.