Research On Seismic Performance Of Precast Segmental Concrete Filled Steel Tube Column

In recent years, infrastructure construction has stept into a new stage in China. Bridge engineering is an important part of transportation infrastructure, which will also usher in an important period of development opportunities. The existing RC bridge design, build, and maintaining are based on the cast-in-place concrete technology, which will certainly make some economic and social disadvantages to surrounding environment and existing traffic. Therefore, it is vital to make some innovation and development for present RC bridge, in order to develop more efficient, fast, safe, durable bridge construction technology. Accelerated bridge construction is expected to become the direction of next generation's bridge development. Post-prestressed precast RC structure is based on the self-centering and rapid recovery concept, which is still in the phase of fundamental theory research and has less engineering practice, design specification and reference. Key technologies and seismic performance of post-prestressed precast RC bridge are still immature. It needs to explore reasonable structure and evaluate the seismic ability, and set up corresponding structure seismic design method.In view of the above mentioned situation, this paper introduces the concrete filled steel tube (CFST) to solve the problems about the prefabricated segment assembling column segments, the author comes up with two precast segmental concrete filled steel tube column, one adopts post-tensioned prestessing while the other adopts high-strength bolt to connects the adjacent segments. Considering the critical facto such as the arrangement and the bonded state of prestressing tendons and energy dissipation, the author has studied the key technology and seismic performance of the self-centering post-tensioned precast segmental concrete filled steel tube column. This paper was carried out from three aspects:theoretical analysis, experimental verification and numerical optimization analysis, the main research contents and conclusions are as follows:(1) The author carried out the research work of domestic and foreign prefabricated bridge assembly structure of the lower part of the key technology and basic research, summarized the research status based on the calculation theory and the research to be further carried out of the technology of prestressed precast column, research status of experimental tests and numerical simulation analysis, proposed the main content and technical scheme of this paper.(2) According to the characteristics of segmental precast concrete filled steel tube columns, the author summed up the single plastic hinge model, and determined the critical force of the segment opening and the critical force of prestressing tendon secondary tensioned. By studying the relationship between the openings of each precast segment, the self-centering segmental precast column multi plastic hinge model was obtained, and the relational expression of top force-displacement relation of each segments and bending moment-curvature was derived.(3) The author designed the test of posttensioned self-centering segmental precast concrete filled steel tube columns, while considering the critical facto such as the arrangement and the bonded state of prestressing tendons and energy dissipation, the position of the prestressed tendon and the thickness of the steel pipe. After the test plan design, pouring processing and site assembly, pseudo static test was carried out.(4) Accoding the pseudo-static test, the author obtained the phenomena of the test columns, focused on the Macroscopic mechanical behavior such as the opening and horizontal malposition between the segments, horizontal shear deformation and bending deflection, evaluated the detail mechanics performance such as the hysteretic behavior, ductile capability, resist lateral stiffness, seismic residual deformation, pre-stress variation, strain of the steel tube.(5) Based on the ABAQUS solid element model, two posttensioned self-centering segmental precast concrete filled steel tube columns were simulated to verify the regularities of this experiment. The author also made detailed analysis and parameter optimization for unbonded prestressed and bolted joint effect of posttensioned self-centering segmental precast concrete filled steel tube columns, and eventually found suitable parameter ranges of column which could make the column have a good self-reset ability, increase the energy dissipation capability, exert the good self-centering performance characteristics of prestressed tendon, concrete filled steel tube and steel pipe connection.In this paper, the key technologies for the improvement of self-centering performance and energy dissipation capacity of precast concrete columns were proposed. The validity and reliability of the proposed schemes are verified by test and numerical simulation. This paper also provided theoretical basis for the technical development and engineering practice of the substructure of the prefabricated assembly bridge.