Ultimate Strength Formula for Steel Arches

Abstract

Effective slenderness ratios for inelastic lateral buckling of throughtype arches are determined by utilizing an analogy between an arch and a column. A designer can use the effective slenderness ratio to obtain an ultimate stress for arches by substituting it into a column strength formula. The applicability of the proposed formula is examined by comparing its predictions with those of computer simulations. The computer simulations are carried out for isolated single arches of box section and through‐type braced arch bridges composed of twin box‐section ribs. The shape of the arch axis is either parabolic or circular in elevation and the rise‐to‐span ratios are in the range between 0.1 and 0.2. The cross section of the arch member is either uniform or variable along the longitudinal axis. Combined use of steels of different grade, longitudinal residual stresses and the initial lateral crookedness of the arch members are considered. Subject to the limitations for which it was derived, the proposed formula is shown to be sufficiently accurate for preliminary design purposes.