Plastic collapse load of crown-hinged steel circular arches : a theoretical method

For construction purposes and to avoid detrimental influences of foundation settlements arches are not always made from a single arch-rib but are built by connecting two curvilinear elements at the crown with a hinge. These arches are also known as crown-hinged arches. This paper presents an analytical procedure to approximate the plastic collapse load of circular crown-hinged steel arches. The development of the analytical method employs the lower- and upper bound theorem of plastic theory and the kinematic admissibility requirements. The influence of normal forces on the plastic moment capacity of the steel section is taken into account. The plastic collapse load is obtained by an iterative method as there is a non-linear relationship between the acting loads and the reduction of the plastic moment capacity due to normal forces. Through a comparison with earlier studies and finite element analyses, it is concluded that the proposed iterative method gives good results. Keywords steel crown-hinged arch, plastic collapse load, yield contour, kinematic admissibility, iterative method, plastic theory