Study On Structure Optimization And Seismic Design Method Of High Damping Concrete Composite Core Walls

Core wall is widely used in super high-rise buildings,but the current state of experimental research lags behind engineering applications.The existing experimental researches mainly focus on the axial compression ratio,geometry dimension and reinforcement ratio,however there are few experimental researches on improving seismic performance of core wall.In the experimental research of improving seismic performance of core wall,the scheme of steel-concrete composite(SCC)core wall is mainly put forward,but the research of structural optimization and design method of SCC core tube is insufficient.Therefore,in order to improve the seismic performance of the core wall,this paper proposes a high damping concrete composite(HDCC)core wall.In this thesis,the HDCC core wall is taken as the research object,and the structure optimization and seismic performance design method are the focus of this research,and the seismic behavior of HDCC core wall is studied by means of pseudo-static loading test and numerical simulation.The main contributions are summarized as follows:(1)The quasi-static loading test of HDCC core wall was completed.Five HDCC core walls with different configurations were presented,and the parameters mainly include the setting forms of steel plate bracings and the configurations of boundary elements.The effects of test parameters on failure modes were analyzed.The indexes of bearing capacity,deformation capacity and energy dissipation capacity were compared and evaluated.The feasibility of HDCC core wall to improve the seismic performance of core wall was demonstrated.(2)The influence of the setting form of steel plate bracings on seismic performance was compared and analyzed.The test results indicate that the X-type steel plate bracings should be set in each floor,as the bearing capacity,ductility,accumulative energy and other seismic indicators are larger.After the numerical analysis,it is found that the deformation and energy dissipation capacity of specimen with steel plate bracings in each floor is significantly improved with high axial compression ratio.(3)The improvement of seismic performance by using dense stirrups in boundary elements was discussed.The experiment results show that the dense stirrups in boundary elements can improve the deformation and energy dissipation capacity,but the improvement effect on bearing capacity is not obvious.Numerical analysis indicate that when dense stirrups in boundary elements are adopted with different axial compression ratio,the improvement of the bearing capacity of HDCC core wall is limited,but that of the deformation performance of HDCC core wall can be effectively improved.This phenomenon is similar to that in previous researches on frame column.At the same time,the suggestive values of stirrup characteristic value are proposed for the HDCC core wall and frame column.(4)The improvement of seismic performance by using profile steel and concrete-filled steel tube(CFST)column in boundary elements was discussed.The test results show that the using profile steel and CFST column in boundary elements of core wall both increase the bearing capacity,displacement ductility and accumulated energy dissipation,and the HDCC core wall showed good seismic performance.In addition,compared with way of setting profile steel in boundary elements,the improvement of seismic performance indicators of specimen with CFST column in the boundary elements is much more notable.Numerical analysis manifest that the seismic performance of HDCC core wall can be improved significantly by using the two methods mentioned above under the condition of high axial compression ratio.The effect of steel ratio of inner boundary elements on bearing capacity and stiffness is more obvious,and the steel ratio of corner boundary elements has a certain effect on deformation capacity.(5)The finite element(FE)models of the HDCC core walls were established.Compared with the test results and experimental data of core wall and shear wall with flange of previous literatures,the proposed FE model was verified.By using the validated FE model,the difference of seismic performance for five HDCC core walls under different axial compression ratio was analyzed.At the same time,taking the specimen CW3X-2 as an example,the influence of different embedded details of steel on seismic performance was discussed.After that,the order of the percentages of steel in different components on seismic behavior of HDCC core walls was arranged after the orthogonal analysis.The results show that among the components of the profile steel frame,the steel plate bracing is an important factor affecting the seismic performance of the HDCC core wall.(6)Based on the FE model,the influence of coupling ratio on the seismic performance of HDCC core walls was studied.According to the analysis result of orthogonal design,the order of influence of coupling beam section size,wall limb section size and number of floors on seismic indexes was arranged.Based on the key factor,the reasonable range of coupling ratio was discussed.Furthermore,the influence of single factor on seismic indexes was analyzed in this range,which provided the basis for the preliminary design of HDCC core walls.(7)The performance state of HDCC core wall was divided into 5 levels,which presented as basically intact(including intact),slightly damaged,slightly-moderately damaged,moderately damaged and not-severe damaged based on the method of skeleton curve.Based on 348 numerical results,the parameter analysis was conducted to discuss the influence of impact factors on drift ratio limits at each performance level.The test result show that axial load ratio,span-to-depth ratio of coupling beam and the steel ratio of steel plate bracings have a significant impact on drift ratio;Furthermore,the drift ratio limit under each performance level is presented to provide a reference for seismic performance design of HDCC core walls.