Out-of-plane stability of fixed concrete-filled steel tubular arches under uniformly distributed loads

Abstract

In recent years, concrete-filled steel tubular (CFST) arches have been widely used and the out-of-plane buckling of CFST arches is becoming a major concern. So far, few studies have investigated the out-of-plane behaviors of CFST arches, and no codes have given the design formula of the out-of-plane stability bearing capacity. Therefore, fixed CFST parabolic arches with the circular cross-section under uniformly distributed loads are investigated in this paper. Considering the effect of material and geometric nonlinearity, the distributions of the internal forces and deformations are observed, and on this basis, an equivalent column model is established to derive the out-of-plane effective length coefficient. In addition, based on the stability theory, the nominalized slenderness ratio of CFST arches is modified considering the influence of rise-to-span ratios and can be substituted into any available stability coefficient equations in current design codes to calculate the out-of-plane bearing capacity of CFST parabolic arches. The proposed equation which has a similar formula form as those available stability equations in existing designing codes for CFST or steel members and meanwhile has equal or higher accuracy as the equations in available literature would be easier for the designers to accept and use.