The Study Of Geometric Nonlinear Element Stiffness Matrix And The Analysis Of Deforming Behavior Of Portal Frame With Tapered Members

Portal frame structure with tapered members had a lot of advantages, such as lightweight, fast constructing, high economic benefit, etc. It had become a very important branch in steel structure buildings. Therefore, many domestic and foreign specialists were interested in investigating the geometric nonlinear behavior of such structures.This paper introduced the development of Finite-Element-Method, and generally reviewed the remarkable geometric nonlinear Finite-Element-Method studying results.Based on beam element stiffness matrix derivation, analyzed the weakness of traditional element stiffness matrix, which the assumed displacement curve function was uncompleted, thus brought up a new method of applying high-ordered polynomials to construct stiffness matrix. Compared by examples, the new matrix could effectively supply the traditional one.Applied Virtual Work Principles and Minimum Potential Energy Theory to verify the nonlinear stiffness matrix, and found out thediscrepancies of geometric stiffness matrix k_σ.Analyzed whether or not the tapered member fit the classical formula of EI(x)·y" = M(x), then argued that the formula could be applied in appropriate conditions. Via it to derive the stiffness matrix, and then...