Experimental Study On Seismic Behavior Of Dry-jointed Precast Concrete Shear Wall

As an important part of building industrialization,precast concrete structures(PCS)has good prospect of application due to its easy construction,energy saving and environmental protection.With the continuous promotion and in-depth study of the PCS,the assembly technology of precast shear wall structure is becoming more mature.Unbonded prestressing connections are widely used in the world as a kind of dry joint so far.Because of the tension of prestressing steel bar increases the difficulty and limits the efficiency of assembly,unbonded prestressing connections can not give full play to quick disassembly and assembly of dry joint.Referring to the joint form of steel structure,two dry joints connected by bolts are proposed to realize rapid disassembly and assembly of the precast shear wall.We made corresponding full-scale shear wall specimens and finished the seismic test.The effect of semi-rigidity of joints on the deformation of specimens was studied by theoretical method.Based on the test results and theoretical analysis,suggestions for seismic design of dry-jointed precast shear walls were put forward.The main contents are as follow:1?H-section steel joint and box-section steel joint were proposed as the new type dry joints.We have designed and manufactured the precast shear wall specimens with H-section steel joint and box-section steel joint respectively.After quasi-static cyclic loading test has been finished we observed the bending failure of shear wall specimensand the displacement angles meet the requirements of seismic code.Deformation of joints showed obvious semi-rigid characteristics during loading.Comparing the hysteretic curves of precast shear walls with H-section steel joint box-section steel joint we knew that the curve of the specimen with H-section steel joint is fuller.In other words,precast shear wall with H-section steel joint have stronger integrity and better seismic performance.2?A simplified mechanical model of joints was established by component method and a calculation method of rotational stiffness which can reflect the semi-rigid characteristics of joints was established.The theoretical model was proved by experimental data.In addition,we modified the theoretical model to four-parameter power function model to improve the accuracy of theoretical calculation.The lateral displacement of specimens was divided into two parts: cracking deformation and wall rotation.Then we calculated percentage of lateral displacement caused by joints' rotation by the improved theoretical model.Effective bending stiffness was introduced to consider stiffness weakening of precast shear walls with semi-rigid joints.It is concluded that the reduction coefficient of stiffness of precast shear walls with H-section joint and box-section joint are 0.816 and 0.641 respective.3?We put forward the suggestions of seismic design suggestion.Precast shear wall structure layout should be simple and regular,stiffness distribution should be uniform and continuous.The top lateral displacement was limited to meet the usability requirements of the precast structure.Meanwhile the maximum applicable height of precast structure should be reduced on the basis of cast-in-place structure.The limit of displacement angle should be moderately relaxed on the safety assurance of the precast structure.The related work completed in this paper enriches the research of precast concrete structure and provides the basis for revising the code of precast concrete structure.It is of great significance to the popularization and development of precast concrete structures.