Theoretical And Experimental Research On Precast Concrete Shear Wall Isolation Structure

Most high-rise residential buildings are reinforced concrete shear-wall structures in China. With the development of housing industrialization, precast concrete shear wall structure (PCSW structures) will get a widely application. Hence, innovative PCSW structures need to be proposed and studied urgently.Base isolation technology is an effective, economical and practical seismic technology. Many earthquake experiences at home and abroad show that the base isolation technique can improve the seismic performance of the buildings effectively.In this paper, a new type of assembled horizontal connection was proposed, which has the advantages of simple installation and easy construction. Focus on the performance of the new assembled horizontal connection and the PCSW structure, shaking table tests were used to study the seismic performance of the PCSW fixed structure and the PCSW isolation structure. Then incremental dynamic analysis was used to study seismic property and seismic fragility performance of the PCSW isolation structure. Finally, directly displacement-based design method (DDB design method) of the PCSW isolation structure was proposed. The main research contents and the main research results obtained are shown as follows.(1) Shaking table test of PCSW fixed structure with the new type assembled horizontal connections was conducted.In order to investigate seismic properties of PCSW fixed structure, two 1/4 scale shaking table tests were designed and conducted, which were a PCSW fixed structure and a cast-in-situ concrete shear wall fixed structure (CCSW fixed structure). Firstly, the new horizontal connection of precast shear wall was proposed and introduced detailedly. Then, the dynamic properties and structural responses of the two structures were compared using shaking table test. The experimental results indicate that the new horizontal connection of precast shear wall is useful and effectively, which can meet the connection requirement under rare earthquake. Under earthquakes, the PCSW fixed Structure and the CCSW fixed structure have similar dynamic characteristics, failure process and earthquake responses.(2) Shaking table test of PCSW isolation structure was conducted creatively.In order to investigate seismic properties of PCSW isolation structure, a 1/4 scale shaking table test was designed and conducted. The structure with high damping rubber bearings and that without high damping bearings are called PCSW isolation structure and PCSW fixed structure, respectively. The dynamic properties and structural responses of the two structures were compared. The experimental results indicate that the control effect on acceleration, displacement, and shear force is remarkable. The frequencies of the PCSW isolation structure are less than those of the PCSW fixed structure; the damping ratios of PCSW isolation structure are higher than those of the PCSW fixed structure. Maximum accelerations, inter-storey drifts and base shear force for the PCSW fixed structure were significantly reduced with the addition of a HDR isolation system.(3) Numerical simulation of shaking table tests was done using self-compiling programme for precast concrete shear walls.In order to simulate the earthquake responses of the PCSW structures, finite element models of the PCSW isolation structure and PCSW fixed structure were established using software OpenSees. Then, the dynamic properties and structural responses of the two structures were studied using numerical simulation. The numerical results indicate that the numerical results of acceleration responses and displacement responses agree well with the test results. With increase of PGA, acceleration errors and displacement errors between the numerical results and measured results increase. When PGA is 400 gal, acceleration errors and displacement errors between the numerical values and measured values are around 11%.(4) Incremental dynamic analysis was used to evaluate the collapse resistance capacity of the PCSW isolation structures.In order to study the seismic properties of PCSW isolation structure under rare earthquakes, incremental dynamic analysis and seismic fragility analysis of PCSW isolation structures were conducted. Firstly, finite element model of the PCSW isolation structure was established using software OpenSees. Then, far field ground motions (FF the ground motions), near field with pulse ground motions (NFWP ground motions) and near field with no pulse ground motions (NFWNP ground motions) were used in the incremental dynamic analysis. Lastly, seismic fragility analysis was used to study the collapse resistance capacity of the PCSW isolation structure. The results indicate that stiffness hardening effect of the HDR isolation bearings, field characteristics and pulse characteristics of the ground motions have little effect on the seismic property of PCSW isolation structure under rare earthquakes. In the seismic vulnerability analysis, ground motion parameter Sa(T1,?1), which is acceleration response spectrum value corresponding to the first period Y1 of the PCSW isolation structure with damping ratio ?1, is an ideal independent variable to form probability seismic demand model of the PCSW isolation structure, and the ground motion parameter Sa(TF, ?f), which is acceleration response spectrum value corresponding to the first period TF of the PCSW fixed structure with damping ratio ?F, is an ideal independent variable to form the probability seismic demand model of the PCSW fixed structure. Collapse resistance capacity of the PCSW isolation structure is better than that of the PCSW fixed structure.(5) Direct displacement-based design method of PCSW isolation structure was proposed.Based on the properties of HDR isolation bearing and deformation mode of the PCSW structure, direct displacement-based design method (DDB design method) of PCSW isolation structure was proposed. Firstly, performance objectives of the PCSW isolation structure were chosen, which were assigned by the designer to achieve given performance levels, expressed in terms of maximum displacement of the isolation system and maximum inter-story drift. Then, based on the elastic-plastic state of the upper shear wall structure, damping ratio of the whole structure was calculated. Lastly, a numerical example was used to introduce the whole process of the DDB design method, which was verified by the results of dynamic elastic-plastic time history analysis. The results indicate that maximum shear strain of the HDR isolation bearing and maximum inter-story drift of shear wall are two effective structure-performance parameters in the design of the PCSW isolation structure. And the results of the DDB design method are envelopes of nonlinear time history analysis results; therefore DDB design method is a conservative design.