Research On The Seismic Performance And Performance Index Limits Of I-section RC Shear Wall With Low Shearspan Ratio

Performance-based seismic design is the most advanced seismic design method in the word.It is capable to control damage and evaluate the cost of repair under different seismic hazard level.The key step of this design method is to attain the numerical performance criteria which evalutate the damage state of structural elements.At present,the seismic design code in our country has adoped the PBSD method.However,it lacks the numericad permance criteria which represent as deformation such as rotation or drift for structural elements.In high-rise buildings,the reinforced concrete shear walls are the main components of the lateral force resistance.In practical projects,the shear walls are always set flanges at the end.So we call these flanged shear walls as I-section shear walls.There are many low shear-span ratio shear walls in structure.For examples,squat walls may be set in low-rise buildings for same purpose,which aspect ratios is less than or equal to 1.5.In addition,in the frame-support shear wall structure,the level of shear stress is high at the bottom of shear walls which support by the frame,because the rotation of these walls have to be coordinated with walls which link with the ground.Therefor,these two type of shear walls always have small shear-span ratio.This paper study the seismic performance and acceptable deformation limits of I-section RC shear wall with low shear-span ratio by testing.The research mainly includes:(1)Designing eight I-secion RC shear walls which need the requirements of building codes.These specimens include tow aspect ratios,two axial-force ratios and tow vertical reinforment steel ratios in boundary elements.This paper describes the failure phenomenon,the deformation properties,the energy dissipation and the degradation of stiffness of the eight specimens.The test result show that the failure mode of the eight specimens was shear failure after the longitudinal reinforcement yielded,which have considerable deformation.(2)Defining the deformation limit values of six performance levels based on the skeleton curve which were attained by quasistatic tests.According to the failure phenomenon recorded during tests,establishing the relationship between the deformation limits and the damage state of elements.(3)Establishing the deformation limits of I-section RC shear walls controlled by shear by regression analysis.Evaluating the deformation limits which given in this paper and which given in ASCE41-13 based on the test results.The deformation limits given in this paper are more reasonable because they are closer to the test results than those given in ASCE41-13.(4)According to test results of other members in our group,which include rectangular section and other I-section shear walls,comparing the deformation capacity between these two type sections.It shows that the ultimate deformation of I-section shear walls is similar to rectangular section while the failure mode is shear failure.The unltimate deformation of Isection shear walls is 1.37 times of rectangular secton while the failure mode is flexure-shear failure or flexure failure.