Research On The Seismic Behavior Of The Concrete Pier With Core Of Concrete Filled Steel Tube

As the indispensable engineering buildings in the transportation, the seismic issues of the bridge are particularly important. But Throughout the destruction of bridges after the earthquake, Pier especially damaging has brought huge economic losses. In order to improve the seismic performance of the bridge piers, humans tried a lot of different structural forms and the Concrete Pier with Core of Concrete Filled Steel Tube (a new form of pier which is an Ordinary concrete pier with Core of strength Concrete Filled Steel Tube) is a new steel-concrete composite structure.In this thesis, through the quasi-static test we hope to research the seismic performance of the new form of pier under cyclic loading, such as destructive patterns, hysteresis curves, skeleton curves, energy dissipation capacity, ductility, strength degradation and stiffness degradation. Then we conducted Numerical simulation analysis on the test model, compared the experimental results and the simulation results,corrected each other to provide the trial reference and analysis data for the seismic performance of such structure, methodological guidance and credible conclusiontest for the study and also a reference for China’s pier seismic design.Firstly we elaborate the earthquake promoting the seismic theory and bridge seismic theory development. Second, in order to identify the factors that affect the performance of the pier ductility we consult a large number of quasi-static orthogonal experimental literature and review the main results and seismic behavior of the existing steel pipe concrete piers which provides the necessary reference for realizing the thesis purpose and designing the static test program. Then by the pier static test we identify and analysis the factors affecting the pier ductility. Finally, the OpenSees model is established to analyze the factors that affect the pier seismic performance. The main contents as follows:(1) Firstly, the devastating earthquakes which produce the great significance of the development of the bridge seismic theory. Then the current theoretical methods of the seismic design are proposed. Then we inspect a large number of experimental literatures and state the results of previous trials on the specimen parameters, considerations, the cross-sectional parameters and load position.(2) Pier quasi-static orthogonal test program was researched. (3) The test results were analyzed from the pier strength properties, ductility capacity and we analyzed the impact of different factors on the pier seismic behavior and ductile failure mechanism.(4) Pier quasi-static test OpenSees fiber element model about six factors (the outer concrete strength, the height of pier, longitudinal reinforcement ratio, stirrup ratio, steel ratio, axial compression ratio) was established. The impact of different factors on the pier ductility was analyzed on the Numerical simulation.