Ultimate capacity of completely overlapped tubular joints. II: Behaviouralstudy

This paper presents numerical results on the ultimate strength behaviour in terms of load-displacement characteristics and failure mechanisms of compl etely overlapped tubular joints. The effect of the gap length on the behavi our of the joints is also investigated. In the study, the end of the lap br ace was axially loaded. Criteria were set up to determine the minimum failu re load. It was found that a joint subjected to compression load gave the l owest ultimate capacity. The geometric parameters of the chord were shown t o have an insignificant impact on the joint behaviour. The joint strength i ncreased as the gap reduced. A sharp increase in the joint strength at smal l gap was noted for a relatively high beta (TL)(=d(L)/d(T)=0.768). The Y-jo int capacity was reached at a sufficiently large gap. tau (TL)(=t(L)/t(T)) had a crucial influence on the joint failure behaviour. A relatively mild b eta (TL)(=d(L)/d(T)=0.616) and tau (TL)(=t(L)/t(T)=0.560) resulted in lap b race failure prior to joint collapse. The failure mechanisms changed from " chord" (through brace) bending, followed by localised plastification of the through brace face to yielding of the lap brace when the gap was reduced f rom a large gap to a small gap of 51 mm. (C) 2001 Elsevier Science Ltd. All rights reserved.