Experimental Study On Seismic Capacity Of Precast Prestressed Concrete Frame Structures

Precast concrete frame, whose beam elements and multistory column elements were connected using post-tensioned prestressing tendons, has advantages of precast systems, such as high construction speed, low pollution, assurance of quality and durability, etc. Furthermore, it also has following merits of its own. First, it's helpful to realize the"beam end plastic hinge failure mechanism". Second, the damage of structure induced by earthquake is easy to estimate. Third, it has high restoring capacity and small residual displacement after earthquake, and can be repaired conveniently. Although the precast assembled prestressed concrete frame structures have bright future of development and application, study on its seismic capacity and design methods is few. To study the seismic performance of the precast prestressed concrete frames, four precast prestressed beam-column subassemblages of two types, which were call bonded and partially debonded precast prestressed frames respectively, were tested under cyclic loading. And then theoretical analysis of the beam column connections and the whole frame were carried out utilizing Drain-2DX procedure. Based on the experimental and theoretical studies above, the load-bearing capacity, failure mechanism, hysteresis curves, ductility behavior and also the energy dissipation and self-centering capacity of the beam-column connections and the whole frame were investigated. The main contents of this dissertation can be concluded as follows.By comparing the seismic capacity of precast prestressed concrete frame with that of the cast-in-place prestressed concrete frame, advantages of the former were presented, and then the shear resistant mechanism of the beam-column connections of two kinds of assembling forms were analyzed.Processes of the experiments results and studies on the failure mechanism and seismic capacity of partially debonded post-tensioned precast concrete frame beam-column joint were conducted. According to the behavior of the assemblages, an analytical model using the elements of the computer program DRAIN-2DX was developed for the beam-column assemblage. Afterwards, parametrical analyses were carried out to study their effect on the seismic characters of the joint assemblage.An analytical model of partially debonded post-tensioned precast concrete frame structure was designed using the proposed design approach, and then nonlinear push-over analysis under triangular distributed lateral forces was conducted to the frame to evaluate its seismic capacity. The experimental study and theoretical analysis indicated that the concept of connecting precast concrete beam and column elements using post tensioned prestressing tendons debonded through the joint and for a distance on either side should reduce joint shear stresses, as a result, the beam- column joint could be protected and remain quasi-elastic under seismic actions. Designed rationally, these frame structures could satisfy the seismic requests and have high self-centering capacity with little residual displacement, and thus the initial stiffness would be restored.