ADVANCED ANALYSIS AND DESIGN OF SPATIAL STRUCTURES

Modem limit-state design codes are based on limits of structural resis tance. To determine the 'true' ultimate load-carrying capacity of spat ial structures, an advanced analysis method which considers the intera ction of actual behaviour of individual members with that of the struc ture is required. In the present work, a large-displacement inelastic analysis technique has been adopted to compute the maximum strength of spatial structures considering both member and structure instability. The actual behaviour of individual members in a spatial structure is depicted in the form of an inelastic strut model considering member in itial imperfections as 'enlarged' out-of-straightness. The maximum str ength of the strut is computed based on a member with 'equivalent out- of-straightness' so as to achieve the specification's strength for an axially loaded column. The results obtained by the strut model are sho wn to agree well with those determined using plastic-zone analysis. Th e nonlinear equilibrium equations resulting from geometrical and mater ial nonlinearities are solved using an incremental-iterative numerical scheme based on generalised displacement control method. The effectiv eness of the proposed advanced analysis over the conventional analysis /design approach is demonstrated by application to several space truss problems. The design implications associated with the use of the adva nced analysis ape discussed. (C) 1997 Elsevier Science Ltd.