Seismic Analysis Methods For Prestressed Precast Frame Structures

The industrialization of construction and disaster recovery are the goals and trends of structural engineering development. Design and construction of prestressed precast structures is an effective way to achieve this goal. At present, the study of prestressed precast structures is mainly concentrated in the component level, rare in structure seismic performance.In this paper prestressed precast connections are taken as the research object. The unbonded high-strength prestressed reinforcement is located in the central and mild steels are located in upper and lower position, in order to balance the relations between structure damage control and energy dissipation capacity. This paper focuses on the overall seismic performance of the prestressed precast structures, carrying out the following work accordingly.First of all, summarizes the modeling method of prestressed precast connection. Based on OpenSEES, the Truss element is adopted to model prestressed reinforcement. In order to simulate the cracking behavior of beam column interface, the beam end region is set to only pressure area and determine the reasonable value range of the length of the region. By comparing with the hysteresis curve of the test, proving the reliability of the connection modeling method.Secondly explore the design principle of prestressed precast structures. In order to compare the seismic performance with cast-in-suit structure, this paper proposes the same cross section size of column and beam section and the principle of the same maximum sectional resistance moment. At the same time the area of prestressed reinforcement under different prestressing degree and the mild steels are given. According to the current specification, design a common four layer cast-in-situ concrete frame and prestressed precast frame.Finally through the nonlinear analysis of prestressed precast frame and cast-in-suit frame, compare the seismic performance and the influence of mild steel ratio. Through the Pushover analysis, compare the displacement-base shear curve of two frames based on equivalent section flexural performance. The study shows that under small deformation the curve of two frames is basically in coincidence. As the increase of displacement, the resistance performance of prestressed precast frame is lower than the cast-in-suit frame. Through nonlinear time history analysis, find that under the same maximum sectional resistance moment, the maximum response of structures is basic same, but the residual deformation of the prestressed precast structure is much less than cast-in-suit structure; increase the mild steel area causing little effects on the performance of the structure.