Result Comparisons Between Simplified Design Method And Advanced Non-Linear Analysis For Steel Frames

Traditional anslysis and design methods have many limitations. With the development of computer technology and theories of structural analysis and design, the advaced analysis and design method must be an important trend in future analysis and design practices. But it is great significance and engineering benefit to improve and perfect the excisting simplified analysis method at present.In this paper, in order to check the second-order elastic method that adding a notional lateral loads, some direct imperfection models were established. By this way, the accuracy method in considering the initial imperfections with the notional lateral loads was studied. At the same time, the influences of the the ratio of vertical and lateral load to the simplified method , and the influences of the ratio of frame height and span to the simplified method were studied. The following are the mian contents in detail.Firstly, a nonlinear analysis method that can considering the initial geometric imperfections and residual stress was given. The constitutive laws equation was derived based on the CRC tangent modulus theory, then constitutive-curve was got by a numerical solution, and was used to consider the residual stresses.Secondly, some frame models were selected, then the finite element analytical models were established according to the simpilified method and the accurate method separately. The accuracy of the simpilified method was studied by comparing the results of the two methods, and the influence rules of the parameters were found. And also, whether the notional lateral loads can well consider the initial imperfections were studied.Thirdly, some braced-frame models were selected, then the finite element analytical models were established according to the simpilified method and the accurate method separately, the members were checked according to the seismic provisions or the non- seismic provisions. The applicability of the simpilified method to braced-frames were studied by comparing the results of the two methods, and the influence rules of the parameters were found.