Sok Yee Yeo

Shaking Table Test of the Taiwanese Traditional Dieh-Dou Timber Frame

ABSTRACT This article attempts to explore the dynamic behavior of traditional Dieh-Dou timber structure under different combinations of structural forms and vertical loads. Using time-history record (TCU 084) from the Chi-Chi earthquake, two semi full-scale specimens (Symmetric and Asymmetric) were tested. Results showed that the Symmetric specimen tends to be damaged more easily and faster than the Asymmetric one. Damage pattern generally begins from the bottom Dou members and subsequently spreading upwards to the upper Dou, horizontal Gong members, and adjoining Shu members. Friction force between the contact surfaces is crucial towards the maintenance of overall structure. Increase vertical loadings have significant effect on the natural frequencies and global stiffness of the structure. Using the Single-Degree-Of-Freedom (SDOF) system, the derived stiffness is generally in good agreement with the dynamic results of both forms. This study suggests that the effects of increasing vertical loadings should be taken into consideration for future evaluation.

Mechanical model for complex brackets system of the Taiwanese traditional Dieh-Dou timber structures

A static test was conducted to investigate the elastic and post-yielding structural behaviour of complex brackets system along the corridor frame region of the Taiwanese Dieh-Dou timber structures. One partial fully scaled specimen was loaded horizontally under different vertical loading levels. A mechanical model, focusing mainly on the rotational behaviours of bearing blocks and timber interlocking joints, was developed to estimate the global behaviour of complex brackets of the Dieh-Dou corridor frame region. By assuming each spring stiffness to behave bi-linearly, the model is only valid for the estimation of the primary and secondary stiffnesses. The force–deformation relationship is highly dependent on the rotational spring stiffness and vertical loads. Hence, when a heavier vertical load is imposed onto the structure, yielding rotation increases and subsequently, the yielding moment of the bearing block members is improved further. Generally, the predicted model was in good agreement with the observed results, up to the post-yielding loading level.

Dynamic characteristics of Taiwanese traditional Dieh-Dou timber structures

This study attempts to explore the structural behaviour of traditional Dieh-Dou timber structure under different combinations of bracket structural forms and roof dead loads. The parameters used include two different structural forms (symmetric and asymmetric) and three different levels of roof weight (1.7, 2.6 and 3.5 tons) which represent the span distance between two parallel frames at 3, 4.5 and 6 meters. Two different semi full-scale specimens, made of China Fir (Cunninghamia lanceolata), were mounted and tested on the shaking table of National Centre for Research on Earthquake Engineering (NCREE) in Taipei. Time-history record (TCU 084) from the 1999 Chi-Chi earthquake in Taiwan was used to test at a level of 20, 42, 60, 80 and 100%. System identifications were carried out between every test to monitor the integrity of the structures. Results showed that increase vertical loadings will have significant effect on the natural frequencies and global structural stiffness of the specimens. Next, the experimental results were mapped with the theoretical model for initial stiffness prediction, whereby the entire structural frame was assumed to be a lump mass system with Single-Degree-Of-Freedom (SDOF). The predicted stiffness model is generally in good agreement with the dynamic results of both structural forms. This study suggests that the effects of increasing vertical loadings should be taken into consideration during future evaluation process. Although using SDOF system to estimate the initial stiffness seems highly probable, more work still

Structural behavior of traditional Dieh-Dou timber main frame

ABSTRACT Under different combinations of horizontal and vertical loads, a total of three quasi-static cyclic tests were conducted to investigate the structural behavior of the 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 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 onward. The column-restoring force contributed mainly to the frame’s moment resistance when displacement is small. When frame deformation exceeds 1/50 rad, bending moment from the primary beam dominated the global restoring force. Hence, the 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. Based on the embedment theory and semi-rigid spring concept, a new theoretical model was developed to estimate the global behavior of the Dieh-Dou main frame. Although the prediction tends to be on the conservative side, the predicted model is generally in good agreement with the observed results.