Stress Analysis And In-Plane Stability Of The Gable Portal Frame Members

This paper gives researches and analyses on the tapered members which are widely used in gable portal frame. The researches about this kind of members mainly focus stress analysis and in-plane inelastic stability. The web of the members referred to this paper changes gradually in the direction of the length, but, the dimension of the flange and the thickness of the web plate are changeless, and the I-section of the members are symmetrical in two axes. Analyses of this paper are as follows:Firstly: the shear and normal stresses of tapered members under the transverse load or axial load are done, and the stresses formulas are obtained. The results show that: (1) Tapered members under the transverse load: the stresses formulas of the tapered members and those of the prismatic ones are identical. So, the latter can substitute the former when calculating the stress of the tapered member because the tapering ratios are little in most projects; The difference between the shear formulas of the tapered members and those of the prismatic ones is bigger and bigger as the tapering ratio changing bigger. (2) Tapered members under the axial load: The stresses formulas of the tapered members and those of the prismatic ones are identical.Secondly: Based on the theory of nonlinear finite element, this paper builds a finite element model by software ANSYS8.0, and calculates the ultimate load-carrying capacity. Based on the theory of numerical integration method and the stability, this paper gives a program which can calculate the ultimate load-carrying capacity of the tapered members. This program has a nice accuracy by comparing with the new version of Code for Design of Steel Structure.Thirdly: Based on the program of this paper, the ultimate load-carrying capacity is calculated on the condition of eccentricity e= 1000mm, and the result is compared with that of finite element method and Technical Specification for Steel...