Structural straightening with tension braces using aftershocks – Shaking table study

Straightening of a two story low damage half scale steel structure with residual drift is investigated by shake table testing. A straight structure was initially subjected to a strong shake, so that it had residual displacements after the shaking stopped. Then, several methods were applied to the structure to evaluate their effectiveness in straightening the structure naturally using aftershocks. It was found that when the frame with no brace (NB) was subjected to additional shaking with the same record, residual displacements decreased by −15% on average. Use of a buckling brace (BB) decreased the residual drift by −65% on average and it did not push the frame in the opposite direction. While application of a ratcheting brace (RB) or a gapping brace (GB) led to an average increase of residual displacements by 160% and 50% in the opposite direction respectively. A numerical model developed captured the responses well.