Dynamic Collapse of Frames Under Wind Disturbances

A parametric numerical analysis is conducted on strain-hardening multi-story frames subjected to wind disturbances generated by amplifying a recorded fluctuating wind pressure. The effect of spreading and diminishing of the strain-hardening regions has been taken into account in the one dimensional finite element formulation employed here. The dynamic behavior including in particular the dynamic collapse behavior is extensively examined and the details are presented for the first time. The effect of a fluctuating wind disturbance on a frame may be represented by the required overall plastic strength, the therefore measured by a multiplier (load factor) of the basic design wind loads. There exists a critical frame which just exhibits the dynamic collaps behavior under a wind disturbance. The corresponding critical value of the multiplier has been called the dynamic collapse gust load factor. The factor provides a rational basis for a practical safety factor and is therefore recommended for a more rational method of wind resistant design of ductile structures.