Second order analysis of 3D structures

摘要

The use of rigorous second-order analysis is not a panacea and whatever method of allowing for second-order effects is used, the impact of using inherently less stiff moment resisting frames to resist lateral loads needs to be considered: 1. the first requirement is understanding - the Steel Construction Institute runs an excellent course on "Frame Stability" that deals with second-order effects and on a number of occasions CSC have been called upon to provide half-day seminars on this topic. 2. if λ_(cr) is > 4 be aware of the downsides of using rigorous second-order analysis as a substitute for the clearer and equally effective simple methods given in BS 5950-1: 2000 3. if λ_(cr) is < 4 and hence BS 5950-1: 2000 forces you into using rigorous second-order analysis, consider the impact on constructability, cost effectiveness and behaviour at ultimate and working loads before reaching for that button. 'Floppy' frames can be designed efficiently and effectively to provide robust and safe buildings.