Nonlinear behaviour of pitched roof steel frames subjected to sequential loads

This paper investigates the importance of sequential loads on the ultimate behaviour of pitched roof steel frames. In most previous studies related to inelastic or advanced analysis, loads are assumed to apply proportionally, which contrasts to the more realistic cases of invariant gravitational loads and varying lateral loads due to wind and seismic forces. Based on the previous work on the inelastic and large deflection analysis, the tangent modulus method is coded in a computer program. Numerical examples are given to demonstrate the discrepancy between these two approaches and to indicate the potential danger of using the over-simplified proportional load assumption in design and analysis of semi-rigid pitched roof steel frames.