Aseismic Optimization Design And Analysis Of Structure Based On Design Concept Of Uniform Damage

The building structure will be deformed under external excitation such as earthquake action.If the design scheme is unreasonable,it will cause large deformation or insufficient resistance.Therefore,the structural aseismic optimization design needs to be carried out.The optimization design can not only satisfy the requirements of the seismic codes,but also ensure that the important performance indexes of the structure are optimal,realizing the performance-based seismic design concept.In many structural optimization design methods,the "fully stressed design" is very popular.For building structure,the fully stressed design can be simplified to uniform damage or uniform deformation.Under the action of wind load or multiple earthquakes,the horizontal displacement angles of all floors should be equal or similar;under the action of hurricanes or rare earthquakes,all layers will enter the plastic state at the same time,and the damage degree of each layer is equal or similar.If the uniform damage occurs,the weak layer and concentrated damage can be avoided,and the overall performance is improved in a comprehensive way,which greatly improves the safety of the structure.Based on the concept of uniform damage,seismic optimization design is carried out on continuous variable cross-section structure.The bend-shear structure is simplified as a continuous variable cross-section cantilever,and the assumed cross section functions involve the forms of natural exponential function or power function.The external excitation such as earthquake effect and wind loads are equivalent to three load modes,such as the uniform distribution,the inverted triangle distribution and the inertia correlation distribution.According to the uniform deformation criterion,the second derivative of the absolute displacement curve of the structure equals zero is taken as the optimization target,the continuous displacement equation is established and the optimization results are discussed.The analytical solution of the optimal stiffness and the cross section distribution of the bend-shear structure is obtained.According to the theoretical and numerical results,the uniform damage can be realized if the cross section function is taken as power function,and the optimal distributions of stiffness or cross sections are different for different load distribution modes.The accuracy and the practicability of the analytical solution is verified by the static-dynamic analysis based on finite element method.In view of the shortcomings of the low efficiency of the present structural optimization algorithm,a hybrid intelligent algorithm based on differential evolution algorithm and particle swarm optimization algorithm is proposed.For bend-shear frame structure,the optimization objective is the relative displacement between the structural layers,optimization design of structural floor stiffness based on hybrid intelligent algorithm,obtaining the optimal distribution of floor stiffness.On this basis,study the influence of the randomness of ground motion and the stiffness ratio of beam and column to the optimization results and the distribution of stiffness.A polynomial function is established for optimal floor stiffness ratio and optimal section size ratio.Comparison with existing research results,verifying the established experience function has high accuracy.Based on the optimization results of the above shear and flexural shear frame structures,the optimal layout design is carried out for existing structures or Uniform stiffness structures.The results show that the optimal stiffness distribution decreases from the bottom to the top,and the curve gradually decreases with the increase of architectural layers.For structure of the viscoelastic dampers,the shear area is selected to be optimized,and the optimal shear area distribution is obtained by the iterative design of the hybrid intelligent algorithm.On this basis,the influence of seismic randomness on the results is studied.The formula fitting is carried out,verifying the accuracy of the fitting formula by comparing with the real value.For the buckling restrained brace structure,based on the concept of uniform damage,the stiffness of buckling restrained brace is optimized.On this basis,the effects of seismic amplitude and seismic randomness on the results are studied.