Research On Reinforcement Design Of Shear Walls With Complex Cross Section Considering Shear Lag Effect

With the accelerated urbanization of modern society, the development of high-rise building becomes the inevitable trend of modern architecture; the reinforced concrete shear-wall is widely used in high-rise structures due to the advantages of its lateral stiffness and large capacity. To satisfy the requirements of engineering, the cross-section form of shear walls becomes more and more complex, at the same time, the bearing capacity of complex cross-section shear walls has always been a problem. The reinforcement design given in the current codes does not consider the complex cross-section shear wall as a whole, besides, because the shear lag in core tube shear walls are usually lack of consideration and research, the relevant values of effective flange width are not sufficiently validated. Therefore, there are insecurity and economic problems.Under the action of horizontal loads, a shear flow would be developed between the web and the flange panels and ,due to the existence of the shear deformations, the strain distribution of the cross-section of core tube shear walls no longer satisfies the plane section assumption, the normal stress in the flange section of the corner is larger than the middle, which leading to the reduction of the effectiveness of the webs and flanges and the inaccurate calculation of bearing capacity. So in the projects, the concept of effective flange width is brought in as a discount of the flange width to measure the degree of shear lag. In order to study the shear lag factors of the core tube walls and give some recommendations to the values of effective flange width, a series of finite element core tube wall models are simulated and parametrically analyzed in the paper. The main contents and conclusions of the paper are as follows:(1) Through a series of finite element analysis of the parametric models, a detailed description of the distribution of stress and strain of the web and the flange is made, the impact of the axial load ratio, shear span ratio, and the stiffness of coupling beam on the shear lag effect is studied, the core tube shear lag effect of the different factors in the variation is presented, and the mechanism of shear lag phenomenon is deeply explored;(2)The calculating method of effective flange width in elastic stage is proposed, the approximate values of effective flange width are obtained by numerical simulation model of the core tubes under different conditions, the capacity skeleton curves are drew, the relevant reinforcement methods results are proposed and compared to the existing research, as a reference to the engineering design.