Study On Damping Characteristics And Dynamic Response Of ECC/RC Prefabricated Shear Wall Structure

The dynamic responses of prefabricated shear wall structure are one of the important indexes to evaluate the safety of structural system.The dynamic responses under dynamic loads depends largely on the damping characteristics.The damping characteristics of prefabricated reinforced concrete shear wall structures is smaller due to the poor ductility,toughness and ultimate tensile strain of concrete as a common building material.Engineered Cementation Composites(ECC)has the similar compressive strength with concrete,higher material damping and energy dissipation,which can effectively dissipate the seismic energy of structures.In order to reduce the dynamic responses of prefabricated shear wall,ECC material was used in the prefabricated shear wall structure in this paper to delay the brittle failure of key parts of shear wall,which can not only exert the high energy dissipation of ECC material,but avoid the poor energy-dissipating capacity of shear wall due to premature brittle failure.In view of those,the damping characteristics and dynamic responses of ECC/RC assembled shear wall were studied based on numerical simulation and theoretical analysis.Additionally,a parameter study was conducted to investigate the influence of critical parameters on dynamic responses.The main research works and conclusions of this paper are as follows:1.Theoretical study on damping ratio of ECC and RC components.Based on the previous test results of our research group,the constitutive relationship of ECC materials was obtained in preparation for the subsequent finite element analysis.,the influencing factors and changing rules of damping ratio were analyzed using the actual measured damping ratio data of ECC and RC components in the literature.In addition,the calculation formulas of damping ratio considering other factors of RC and ECC components were proposed,and the differences between the above two formulas were compared and analyzed.2.Nonlinear damping study on ECC and RC prefabricated shear wall structures.The nonlinear damping formula and finite element model of RC assembled shear wall structure were established based on the data in literature.Additionally,the relationship between damping ratio and structural deformation was analyzed,and the finite element model and nonlinear damping formula were verified.Moreover,the ECC assembled shear wall structure model and nonlinear damping calculation formula were established using the analysis model of RC assembled shear wall structure by replacing ECC material.The proportion of material damping and structure damping of ECC and RC shear wall were compared and analyzed.The results show that the damping ratio increased with the increase of structural deformation,indicating that the structure changed from low damping stage to high damping stage.Structural damping played a major role when RC shear wall structures enter the stage of high damping performance.When ECC shear wall structure entered the stage of high damping performance,and material damping played a major role.The superiority of ECC material’s damping performance can be seen from the material damping ratio,and the damping ratio of ECC material was approximately 270% higher than that of ordinary concrete.3.Dynamic responses of ECC/RC prefabricated shear wall structure with different ECC strengthened layers.For the bottom five floors of the overall structure model,RC materials were replaced using ECC materials in the bottom one,two,three,four and five floors respectively,forming ECC/RC prefabricated shear wall structures with different ECC strengthened layers.Based on the damping ratio theory and numerical analysis model of the whole structure in this paper,the finite element analysis of ECC and RC prefabricated shear wall structures was carried out by considering the nonlinear damping performance of buildings.In addition,the static elastic-plastic analysis study was conducted through the revised demand spectrum.Considering the bidirectional seismic action,the dynamic elastic-plastic time history analysis was carried out under different seismic waves to complete the dynamic response evaluation of the structure.The calculation results of ECC/RC prefabricated shear walls with different ECC strengthened layers were compared and analyzed.The results show that the most suitable strengthened layers were about the bottom three layers,which can meet the requirement of 10% of the strengthened height for structure in the specifications.