Buckling behaviour of composite double-layer braced barrel vaults

Investigation of different potential instability phenomena is an essential part of a study of the structural behaviour of double-layer braced barrel vaults. In this context, the effects of the use of a reinforced concrete (RC) topping in composite action with double-layer grid-works on the instability behaviour of such structures were studied. Two types of double-layer flat grids and barrel vaults were considered: without any integral RC topping (non-composite grid-works) and with a RC topping in composite action with the spatial grid (composite grid-works). The primary models were selected and designed adopting a consistent procedure utilising the weight–density method. Initially, elastic buckling analyses were performed. Complementary studies included a series of non-linear finite-element analyses accounting for geometric and material non-linearities emphasising structural stability and the post-buckling behaviour. It was found that the presence of a rather thin layer of RC covering, in composite action with double-layer grids, increased both the initial buckling and the ultimate strengths of such structures substantially, and also significantly improved their post-buckling behaviour, resulting in much improved reliability against progressive failure and sudden loss of strength.