Advanced analysis and design of spatial structures

Abstract

Modern limit-state design codes are based on limits of structural resistance. To determine the 'true' ultimate load-carrying capacity of spatial structures, an advanced analysis method which considers the interaction of actual behaviour of individual members with that of the structure 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 initial imperfections as 'enlarged' out-of-straightness. The maximum strength 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 shown to agree well with those determined using plastic-zone analysis. The nonlinear equilibrium equations resulting from geometrical and material nonlinearities are solved using an incremental-iterative numerical scheme based on generalised displacement control method. The effectiveness 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 advanced analysis are discussed. © 1997 Elsevier Science Ltd.