Experimental and numerical investigations on out-of-plane ultimate resistance of parallel twin-arch under uniform radial load

摘要

Studies on out-of-plane buckling of parallel twin-arch with lateral braces are lacking in contrast to free-standing arches, although they have been widely used in the engineering practice. This paper deals with experimental investigations into out-of-plane ultimate resistance of fixed circular parallel twin-arch under uniform radial load. Seven parallel twin-arch consisting of two steel tubular arch ribs connected by lateral braces are tested under symmetric radial loading. A loading frame comprising a reaction beam, sliding supports and distribution beams is used to apply five-point radial loads over the full span of the arch ribs. Initial out-of-plane imperfections are generated by a push rod before loading. The test results show that all of the specimens fail in an out-of-plane symmetric C-shaped buckling mode, and the lateral displacements are much larger than the vertical displacements. It is also found that the stiffness of the lateral braces have great effects on the ultimate resistance of the parallel twin-arch. The ultimate resistance increases as the cross-section diameter of lateral braces increase. A finite element model is also developed. Comparisons of the FE results for the out-of-plane elasto-plastic behaviour of parallel twin-arch with the experimental ones indicate that the finite element model can predict the elasto-plastic out-of-plane buckling response of parallel twin-arch very well.