Plastic Damage Research And Yield Mechanism Optimization Of Shear Wall With Shock-absorbing Coupling Beam

Shear walls have relatively high lateral stiffness and strength but insufficient deformation capacity.The shear wall with shock-absorbing coupling beam（SACB）adjusts its stiffness of the coupling beam by setting a damper on the coupling beam to optimize the yield mechanism.Currently,most of the dampers used in SACB are metal or viscoelastic dampers,which have disadvantages such as complex force transmission mechanism and difficult recovery after deformation.The purpose of this thesis is to use the geometric nonlinearity of the multistable structure to design a new type of SACB,which doesn’t require material yielding or plastic deformation,and to study the yield mechanism optimization of the shear wall based on the multi-stable structure.We firstly deduced the mechanical model and strain formula of variable crosssection bistable supports（VCBS）through the chained beam constraint model（CBCM）.Then we designed a new type of SACB damper and the corresponding new SACB using the geometric nonlinearity of VCBS.And finally we put forward an optimization method of the yield mechanism using this new SACB.The main research work and results of this thesis are summarized as follows:（1）We derived the CBCM applicable to the VCBS and the calculation formula of axial normal strain under this model.We also carried out the FE verification and 8 variable cross-section bistable support verification experiments.The FE and experimental verification results show that the CBCM and the derived strain calculation formula are accurate and effective.（2）We uses the CBCM to study the relationship between the geometric and mechanical parameters of VCBS,and then develop and design a new type of SACB damper using the VCBS and the viscoelastic material in parallel,as well as the corresponding SACB.FE verification shows that the new type of SACB damper can illustrate quasi-zero stiffness characteristics as expected,and the designed SACB has the characteristics of flexible adjustment of stiffness according to the demand.（3）We proposed a method by which the yield mechanism of shear walls can be optimized using the new SACB with different stiffnesses.We derived a design formula for optimizing the yield mechanism of the shear wall using the flexibly adjustable stiffness character of the SACB,and put forward a modification method that focuses more on the mechanical performance.Another method for improving the optimal design by strengthening the SACB on the top of wall is given.The results show that the shear wall with "lower strong and upper weaker" coupling beams has more uniform stress distribution.The proposed optimization design methods can optimize the yield mechanism of the shear wall as required.The main innovations of this thesis are:（1）A simplified calculation method for designing SACB with VCBS.The CBCM is derived to calculate the strain formula of VCBS.Based on this,we designed two SACB dampers for adjusting the stiffness coupling beam and optimizing the yield mechanism of the shear wall.A lever-type SACB was designed using bistable support dampers;（2）The design method and idea of using the SACB to optimize the yield mechanism of the shear wall.Using the above-mentioned SACB with bistable support dampers,we proposed a method for optimizing the plastic yield mechanism by SACB with different stiffness in a shear wall and subsequent improvement idea.The geometrically nonlinear character of VCBS can be used in yield mechanism optimization of the shear wall coupling beam.