Structural behavior of traditional Dieh-Dou timber main frame

Under different combinations of horizontal and vertical loads, a total of three static cyclic tests were conducted to investigate the in-plane structural behaviour of the traditional Dieh-Dou timber frame. Typical deformation patterns include column rocking, joint rotation around the primary beam-column and column Dou-column regions, vertical shear around the upper and lower end of column mortise, embedment around primary beam-column regions and vertical shearing around the mortise regions of the Dou members. Visible deformation generally began from 1/30 rad onwards. Column restoring force contributed mainly to the main frame’s moment resistance when displacement is small. When frame deformation exceeds 1/50 rad, bending moment from the primary beam dominated the frame’s global restoring force. Hence, column restoring force and the primary beam-column connection generally undertake the primary moment-resisting mechanism while the complex bracket structures above the primary beam play a secondary role. Base on embedment theory and semi-rigid spring model, a new theoretical model was developed to estimate the global behaviour for the global system of Dieh-Dou main frame. The current model can only estimate the initial and secondary stiffness as the spring stiffness are assumed to behave bi-linearly. Hence, it is unable to predict the out-of-plane failure phenomena and ultimate failure load at this moment. Although the prediction tends to be on the conservative side, the predicted model is generally in good agreement with observed results.