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To-date, limited number of fundamental studies on the structural behaviour of Dieh-Dou timber frames and its joint connections can be found. Hence, there is an urgency to study and evaluate the seismic performance of the existing Dieh-Dou timber frame buildings so as to prevent as much earthquake-inflicted damages as possible from occurring in the...
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The Kaybob compressor failure of 1971 was an excellent historic example of rotordynamic instability and the design factors that affect this phenomenon. In the case of Kaybob, the use of poorly designed bearings produced unstable whirling in both the low and high pressure compressors. This required over five months of vibration troubleshooting and r...
Citations
... Based on a field investigation and a series of tests, Yeo indicates that the Zuo-Dou is vulnerable under vertical and horizontal loads. [6] When the Zuo-Dou bracket system is subjected to seismic impacts, the shear force causes cracks in the Zuo-Dou connections; the connections are not only those within the bracket system but also those which are beam-to-column joints. The profile of a Zuo-Dou on the top of a column is illustrated in Figure 3. Normally, the fibre's direction of Shu is in the plane of the Dieh-Dou timber frame, while the Hang-In's orientation is perpendicular or out of the plane. ...
... These phenomena reduce the overall capacity of the Zuo-Dou connection. One of Yeo's conclusions proves that the geometric layout of the Zuo-Dou influences its mechanical properties [6,7]. To date, however, few studies have dealt with the correlation the Zuo-Dou's profile and its structural characteristics. ...
... Microscopically, the relative movement of the associated components in the Zuo-Dou generates. Yeo delineates the deformation and potential cracks of the Zuo-Dou, as can be seen in Figure 5 [6]. The deformation of the building results in the horizontal moment M and subsequent rotation and deformation, as depicted in Figure 5a. ...
This paper is focused on the retrofitting techniques of Zuo-Dou connections in Dieh-Dou timber frames in Far East Asia. The target is to develop appropriate techniques for the reinforcement and maintenance of the wooden cultural heritage. A series of full-scale tests are intended for the evaluation of the rotational and shear characteristics of the various retrofitting techniques for the Zuo-Dou joints. These retrofitting techniques are conceived by this study based on the principles of the conservation of cultural heritage. The reversible materials, invisible layouts, and structurally efficient schemes are taken into account to figure out the reinforcement strategies. Regarding the conservation targets, this study applies the self-tapping screw (STS) and the bamboo nail for reinforcement. Corresponding to the loading circumstances, moment- and shear-constraining schemes are developed. The STS and the bamboo nail are applied by means of moment- or shear-constraining strategies. Then, rotational and shear tests are carried out to estimate the structural efficiency of the conceived retrofitting techniques. With the appropriate schemes, the STS and the bamboo nail contribute to the enhancement of the structural performance of the Zuo-Dou connection. The STS in a moment-constraining profile can ameliorate the Zuo-Dou’s rotational behaviour. As far as post retrofitting and preventing reinforcing are concerned, the STS reveals considerable structural efficiency. The bamboo nail in a shear-constraining scheme can increase the shear capacity of the Zuo-Dou joint. Besides the quantitative outcomes, these retrofitting techniques exhibit ductility and enhance the deformation processes of the connections. With the alternative fasteners, the slump or vibration during the deformation becomes moderate and the severe damages, such as rocking or block shear failure, are alleviated. The techniques and associated materials used in this study exhibit compatibility and feasibility for constraining the rotation, deformation, and crack of the Zuo-Dou connection. These effects are helpful for retaining the joints’ structural behaviour and contribute to the conservation of traditional timber constructions.
... Due to the complexity of oriental timber frame construction and the lack of proper seismic evaluation methods for this type of traditional structures, the conventional practice is either to neglect or to set all timber joints as hinged, by assuming that these traditional timber connections bear no moment resistance. From the past related test results [1]- [11], it is observed that the oriental timber joint connections generally performed more like semi-rigid joints than hinges and that, oriental timber joints tend to slip when subjected to lateral force. The overall stiffness of the global structure is also found to be closely related to vertical loads, friction and partial embedment of wood fibres between contact surfaces. ...
... With reference to hysteresis loops and test observations of both static and dynamic tests [6], [11], the elastic range of the complex brackets falls around 2 to 5 kN before entering into first yielding stage. The structure then moved on to the elasto-plastic stage with an approximate range between 5 and 10 kN. ...
... The structure then moved on to the elasto-plastic stage with an approximate range between 5 and 10 kN. Signs of visible deformation, either in the form of shear fracture (horizontal, vertical or diagonal types) or friction-induced partial embedment usually will be manifested during this stage [5], [6], [11]. Base on the above observations, the initial plan was to extract three stages of the lateral force loading, namely 5, 10 and 15 kN, to find out if the predicted stress distribution of each structural component will coincide with the upcoming damage patterns as observed in the shaking table tests. ...
A series of in-plane structural studies of the traditional timber structures have been conducted since the 1999 Chi-Chi earthquake. Most of these studies were largely based on quasi-static tests, limited modelling studies are found on the dynamic behaviour of these structural types, in particular, the complex bracket systems. Owing to its complexity and the lack of proper seismic evaluation methods for this type of oriental timber structures, structural engineers often assume these timber connections bear no moment resistance, and thus, will tend to simplify them to two idealized extreme forms – fully rigid or fully-hinge/pin joint. Hence, the predicted outcomes often appeared to be unrealistic as they do not truly reflect the actual behaviour of the oriental timber structures. Under-estimation not only give the public a misguided perception that traditional timber structures are weak and not durable; it also undermines its true seismic capability. From past experimental results, it is understood that oriental timber joints generally behaved like semi-rigid joints than hinges or pin, and the overall stiffness of the global structure is related to vertical loads, friction and partial embedment of wood fibers between contact surfaces. Close-form analytical models have been derived and the predictions fit well with the test results. For verification sake, the above models were subjected to two examinations. Firstly, the models’ assumptions and calculated values were cross-validated with past dynamic tests of complex bracket sets with various vertical loads and structural system designs. Next, the calculated assumptions were applied to conventional numerical modelling software and the predictions were cross-referenced with test results. Preliminary results from the above examinations revealed that the predicted models and anticipated weak points of the global structures were generally in good agreement with the dynamic test results; hence the assumptions made generally work well in both static and dynamic tests.
... A total of three full-scale specimens were tested to study the in-plane structural behaviour of the Dieh-Dou internal main frame. The building width interval of the Dieh-Dou timber frame has been studied (Yeo 2016) and can be broadly sorted into three main categories: 3, 4.5 and 6 m. Base on Shih's (2014) roof dead load calculation, the estimated roof weights for 3-, 4.5-and 6-m building width intervals were 20, 31 and 40 kN, respectively (Table 1). ...
... For simplicity sake, a schematic global spring model (Figure 13b) will be used for the rest of the discussion. Detailed explanation and derivation of rotational springs and the mechanical modelling for the internal main frame have been described in Yeo (2016 and2016b) and will not be repeated in this paper. 7 ...
... Figure 1. A typical Taiwanese Dieh-Dou timber building layout design (Yeo 2016). Figure 2. Typical damages observed in Dieh-Dou timber frame after the Chi-Chi earthquake: Joint dislocation occurring at (a) timber column base-stone column (Tsai 2009) and (b) timber column-beam region (NCKURDF 2001) and, (c) Shear crack causing misalignment of complex brackets (NCKURDF 2001). ...
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.
... Overview of a typical single Taiwanese Dieh-Dou timber frame [1] In the case of Taiwan, the Dieh-Dou type and Chuan-Dou type traditional timber frames are commonly found in temples, ancestral halls and residential houses, as shown in Figure 2. : Butt-joint is commonly used for the primary beamcolumn connection for the Dieh-Dou type internal main frame [1] Considering both Taiwan and Japan encounter similar natural calamities such as earthquakes and typhoons on a yearly basis, the general analytical concepts developed by the Japanese academics might be Half-penetrating beam (a) more applicable to the Taiwanese context, hence the Japanese approach was used in this study. ...
... Overview of a typical single Taiwanese Dieh-Dou timber frame [1] In the case of Taiwan, the Dieh-Dou type and Chuan-Dou type traditional timber frames are commonly found in temples, ancestral halls and residential houses, as shown in Figure 2. : Butt-joint is commonly used for the primary beamcolumn connection for the Dieh-Dou type internal main frame [1] Considering both Taiwan and Japan encounter similar natural calamities such as earthquakes and typhoons on a yearly basis, the general analytical concepts developed by the Japanese academics might be Half-penetrating beam (a) more applicable to the Taiwanese context, hence the Japanese approach was used in this study. ...
The structural performance of the Taiwanese traditional timber frame is studied in order to clarify the effects of the column, beam and Dou region in the global frame. Cyclic horizontal loading test with constant vertical force was applied to the China Fir specimens. Results shown that the moment-resisting effect of the 'full-penetrating beam' tests is generally twice that of the 'half-penetrating beam' case. The material properties of structural members such as Dou and beam have critical impact on the overall performance of the timber frame. The Cha-Jiao member, a commonly neglected member, was found to have significant moment resistance in the 'pull-in' tests of the 'half-penetrating beam' case. This study suggests that the Cha-Jiao member should be taken into consideration during structural evaluation in future.
