The Effect of Initial Geometric Imperfection on the Load Bearing Capacity of Double Layer Barrel Vault Space Structures

Abstract eng:
The existence of some geometrically imperfect members in space structures are almost inevitable, beside that there are some imperfections in botching the structures and the fact that they are effective in producing internal forces is undeniable. When a compressing member yields, in spite of that, continues bearing a lot of load, on the other hand the buckled compressive member goes to a critical situation and losses its stiffness and shed its load on the other members, causing a progressive collapse. Double layer barrel vaults which have statically highly indeterminate degree , may cause this phenomena because of unsuitable members .As the members initial curvature is the most popular geometric imperfection which is common in practical structures , in this thesis has chosen as an effective imperfection ,for research. We have tried to study this effect on the load bearing capacity of model structure. The selected model is a double layer barrel vault which is subjected to uniform concentrated load applied vertically downward to each node of the upper layer and members assumed to be pin-ended .The ratio of pure height of structure to pure opening mouth is 0.22 and the kind of layers decoration is a square on square. Two forms of analysis carried out; one for monotonous imperfections and the other for 30 cases of random imperfections which based on Monte Carlo Methods. After analysis, the ratio of maximum reduction to common case was about %41, also the suitable way of certain conclusion is presented with Monte Carlo Method.

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