Mechanic Model And Newmark-precision Time History Analysis On Short-leg Shear Wall Structure

Short-leg shear wall structure has the advantages of frame and shear. However, mechanical model, dynamic behavior and analytical method on this structure need to be researched more deeply.Precise time integration method is applied in short-leg shear wall, and a new scheme is put forward which is referred as Newmark-precision time history method. Basic assumption of Newmark-β method is introduced into dynamic equation and acceleration vector is eliminated from the dynamic balance equation. As a result the order of the equation is reduced to one order. Then precise time integration method and three-point integral format of Gauss are applied to integrate step by step. Interval formula of Newmark-precision time history method is also developed in this paper. Compared with precise time integration method being applied directly, the order of the equation is reduced to half of it by the scheme in this paper. Effect of decreasing order to matrix is apparent, which is of positive significance to dynamic equation of real large-size structure. It can be found that Newmark-precision time history method has some precision from comparing its calculated results to exact solution.According to mechanical property and deformation feature of short-lag shear wall, special-shaped multi-component model is put up. A new cross section displacement function and degree of freedom of nodes are introduced and improved which consider the effect of shear-lag. Space stiffness matrixes of T-shape and L-shape short-leg shear wall are derived by variational principle and they are corrected because of flexure-shear deformation correlation. It can be found that the model built in this paper accurately reflect the mechanical behavior of short-leg shear wall.On the bases of theory and method, a program is developed by MATLAB. The program is able to draw t time history curve of displacement, speed and acceleration of the building under action of earthquake. Maximum inter-story shear and maximum inter-story displacement can be also calculated. An example is analyzed applying the program, whose results are compared with those of Wilson- θ method. The analyticalresults show that the model in this paper is rational and the method can solve better time history of seismic response. Therefore they can be applied and promoted in analysis of earthquake response.