Experimental Research On Seismic Behaviors Of Squat RC Shear Walls Subjected To Freeze-thaw Cycles

Application of shear wall structure began in the late 1970 s in our country.The shear wall structure is mostly adopted in high-rise building and the reservoir in the industrial buildings.As time goes on,the degradation of frost resisting of these shear wall structures which often store water,directly contact with ground water,rain or steam have appeared gradually.For now,the research on performance of concrete after freezing and thawing focus on the level of concrete material properties.Moreover,based on the research results of concrete material properties,the deterioration law of seismic behaviors of structure or member after freezing and thawing cannot be accurately predicted.Therefore,it becomes particularly important to study on the seismic behaviors of structure or member subjected to freeze-thaw cycles.The main contents in this paper are as follows:(1)Four batch of 8 squat shear walls with shear span ratio of 1.14 were subjected to 0,100,200 and 300 times of freeze-thaw cycles in artificial climate room respectively.And the changing of compressive strength and relative dynamic elastic modulus of concrete after freeze-thaw cycles was analyzed.(2)To study the influence of freeze-thaw,the concrete compressive strength and axial compression ratio on the seismic behaviors of squat shear walls,quasi-static tests were conducted.Based on the experimental results,failure process and pattern of the squat shear walls were described.Some performance indications,such as carrying capacity,ductility,plastic rotation,strength attenuation,stiffness degradation,and cumulative hysteretic energy dissipation,were used to evaluate the deterioration laws of seismic behaviors of squat shear walls.(3)Based on the test results,the skeleton curve of the squat shear walls can be simplified as a trilinear model without descending branch.Then the statistical formulas of characteristic model parameters are established and restoring force models are proposed.Compared with test data,it shows that the restoring force models could correctly simulate the hysteresis curves of squat shear walls which are subjected to freezethaw cycles.