Seismic behaviour of Taiwanese timber complex brackets subjected to out-of-plane loading

The Taiwanese Dieh-Dou-type complex brackets used in traditional timber buildings are commonly believed to sustain both in-plane and out-of-plane loadings of the main frame during seismic events. From past statistical investigation, single-tier, double-tier and triple-tier asymmetric bracket designs were chosen as test subjects. A series of quasi-static cyclic tests was applied to full-scale specimens to evaluate their seismic behaviour when subjected to out-of-plane loading. The test specimens generally exhibited significantly higher resistance when all horizontal members sustained compression. The Gong members functioned like braces and subsequently led to enhanced resistance. However, when the global structure was subjected to tension, the joints of Gong, purlin support and purlin members were more likely to be pulled out. The counter-resistance force observed from the tension side resembled that of rigid-body rotation. The triple-tier specimen sustained more serious damage than the other two types, where the middle Dou member was more prone to split due to stress concentration. The proposed bi-linear semi-rigid spring models were in good agreement with the test results, so the general assumptions made were valid.