Structural modelling of support scaffold systems

Abstract

In this paper, accurate three-dimensional advanced analysis models are developed to capture the behaviour of support scaffold systems, as observed in full-scale subassembly tests consisting of three-by-three bay scaffold systems with various combinations of lift height, number of lifts and jack extension. The paper proposes methods for modelling spigot joints, semi-rigid upright-to-beam connections and base plate eccentricities. Material nonlinearity is taken into account in the models based on the Ramberg–Osgood expression fitted to available experimental data. Actual initial geometric imperfections including member out-of-straightness and storey out-of-plumb are also incorporated in the models. The ultimate loads from the nonlinear analyses were calibrated against failure loads and load–deflection responses obtained from full-scale subassembly tests. The numerical results show very good agreement with tests, indicating that it is possible to accurately predict the behaviour and strength of complex support scaffold systems using material and geometric nonlinear analysis. The paper highlights the main difficulties in the numerical modelling of support scaffold systems, and describes mechanical models for implementing base plate, U-head and spigot joints in the analysis.