Study On Seismic Performance And Design Method Of Monolithic Precast Concrete Shear Wall Structure

The impact of the prefabricated construction process on the seismic performance of the monolithic precast concrete structure in high-intensity areas and the difference between the seismic performance of the cast-in-place shear wall structure and monolithic precast concrete structure are unknow.And the concept of “equivalent cast-in-place” whether could be uesd.The monolithic precast concrete shear wall structure is assembled by the prefabricated concrete shear wall members through a reliable connection and integrated with the post-cast concrete and cement-based grout.In this paper,the grouting connection performance of the steel sleeves connecting the longitudinal bar is analyzed.According to the similarity theory,the 1/5 scale ratio monolithic precast concrete shear wall structure and the comparative analysis of the cast-in-place shear wall structure are designed and fabricated.The dynamic characteristics and seismic performance of the two models were compared by shaking table test.The nonlinear dynamic analysis of the prototype structure was carried out by Open Sees software.Finally,the performance level division standard and quantitative evaluation index of the shear wall structure were proposed.Design points of monolithic precast concrete shear wall structure were proposed.The main research work completed in this paper is as follows:1.The connection performance between the precast elements is the key to monolithic precast concrete shear wall structure.In this paper,the influence of steel anchorage length,grouting strength,steel bar diameter and sleeve material on grout sleevs were studied by drawing test.The damage form of each test specimen and the influence of various factors on the tensile strength of the test specimen were analyzed.Finally,according to the force mechanism of the sleeve grouting connection,the anchor length of semi-grouting sleeve steel bar connection was proposed.2.Considering the construction process of monolithic precast concrete shear wall structure,a 1/5 scale assembled monolithic shear wall model structure was designed and manufactured.According to the test results of the shaking table test,the crack shape and failure mechanism of the monolithic precast concrete shear wall structure,the dynamic characteristics such as frequency,period and vibration mode,seismic response such as acceleration and displacement,and the base shear coefficient were analyzed.The following conclusions are drawn: the typical crack shape of the structure was the horizontal crack between the prefabricated elements at the bottom or the top of overlapping joint beam;the initial damage of the connection of prefabricated elements caused the frequency to decrease greatly under the first seismic action condition;The seismic response of the structure increased with the increase of the acceleration peak in the stage of PGA of 0.035g?0.14 g.After the stage,each parameter exhibited obvious nonlinear characteristics.3.Through the shaking table test research,the differences in seismic performance between the monolithic precast concrete shear wall structure and the cast-in-place shear wall structure were compared and analyzed,including the overall structural crack morphology,failure mechanism,dynamic characteristics and seismic response parameters.The following conclusions: the typical crack of the monolithic precast concrete shear wall structure was the horizontal crack,and the cast-in-situ structure was the plastic zone of the end of the coupling beam;the initial frequency of the former was larger than that of the cast-in-place structure under the first seismic condition.However,the damping ratio and the mode of vibration coefficient were basically the same;the acceleration amplification factor of the integral shear wall structure was reduced by more than the latter;the cast-in-place structure was seriously damaged by the fourth layer in the plastic phase,and the floor displacement above the part was larger than the monolithic precast concrete shear wall structure;the inter-layer displacement angle values of them met the national standard limits;other seismic response coefficients,such as seismic action,base shear coefficient,overturning moment coefficient,hysteretic energy,equivalent lateral stiffness,etc.were exhibited obvious nonlinear characteristics under the strong earthquake.The difference in seismic response between them indicated that the design parameters of the integrated monolithic shear wall structure should be distinguished from the cast-in-place structure.4.In the Open Sees analysis platform,the analysis program of the prototype structure shear wall was compiled,and the nonlinear dynamic analysis was carried out.The prototype structure of the cast-in-place shear wall was compared with the cast-in-place model structure and the monolithic precast concrete shear wall structure.Acceleration time history curve,displacement time history curve,acceleration amplification factor,floor displacement and other hysteresis performance of the prototype structure verified the reliability of the finite element analysis model,and had better calculation accuracy.5.Based on the results of the shaking table test,the classification criteria and performance level of the seismic damage grade of the monolithic precast concrete shear wall structure and the cast-in-place shear wall structure were proposed.The performance based on the interlayer displacement angle and damage index were given.The horizontal quantization standard and the two-parameter damage calculation model were combined with the experimental phenomena to analyze the damage of the two structures under the full working condition.The calculation formula of the damage index based on the acceleration peak was given for reference.Based on the difference of seismic response of monolithic precast concrete shear wall structure and cast-in-situ shear wall structure,the design points monolithic precast concrete shear wall structure were summarized.