Min Fu Hsu

Rotational performance of traditional Nuki joints with gap I: theory and verification

The Nuki joints in Taiwan and Japan are similar in appearance; however, due to lack of wedges used in Nuki joints in Taiwan, the gap between the column and beam increases the complexity of timber joints. In this article, the rotational performance of traditional timber joints is reported. A theoretical model considering Hook’s law and Hankinson’s formula was developed for predicting the rotational performance of Nuki joints with gaps. A total of 24 specimens was tested and used to verify the rotational performance of timber joints. The proposed model not only predicts the rotational stiffness of Nuki joints, but can also estimate the initial slip of these joints. Good agreement was found between predicted and experimental data.

On mechanical behavior of traditional timber shear wall in Taiwan I : background and theory derivation

The objectives of this study were to explore the mechanical behavior of traditional timber shear walls in Taiwan and to propose a theoretical model to predict their lateral force resistance. An extensive field investigation was conducted, and the dimensions, tectonic detail, and materials used were recorded. The data collected were used as the reference for theoretical derivation and experimental design. In the theoretical model, the moment resistance of entire shear walls was derived from the contributions of the moment-resisting capacity supplied not only by embedment and friction action between board units and beams but also the dowel action of bamboo nails. Timber shear walls with various geometric conditions and material properties are considered. The theoretical model demonstrated in this study can be used to predict the mechanical behavior of timber shear walls and will be verified by experiments in our next article.

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

On mechanical behavior of traditional timber shear wall in Taiwan II: Simplified calculation and experimental verification

In the previous report of this ongoing study, results of an extensive field survey were collated and a theoretical model was proposed to predict the mechanical behavior of timber shear walls of traditional design in Taiwan. The initial objective of the present report was to propose a simplified calculation method for estimating the initial stiffness and yield strength of traditional timber shear walls. Based on the results of the field survey, a total of 15 full-scale specimens were tested to verify the theoretical model and simplified calculation proposed previously. Good agreement was found from comparison of analytical and experimental results. The results of this study show that the friction behavior between board units and beams plays the major role in resisting the lateral force applied on the timber shear wall, followed by the resistance supplied by embedment. The resistance provided by bamboo nails is minor due to the small section. Another trend found was that for set dimensions of a timber shear wall, the board width can be increased to obtain higher stiffness and strength of the shear wall.

A new proposal to reinforce planked timber shear walls

Timber is one of the most common materials used in traditional buildings worldwide. Our previous research has suggested that timber shear walls play an important role in resisting external loadings, such as earthquakes. Thus, improving the structural performance of in-filled shear walls can also improve that of the entire structure. In the traditional Taiwanese timber shear wall system, the embedment strength of beams and friction between wooden planks and beams significantly affect the strength of the shear wall. This article proposes a new method of reinforcing traditional timber shear walls in Taiwan by inserting teak and padauk strips into the grooves between wooden planks and beams to increase the embedment strength of beams and the friction between wooden planks and the hardwood strips. A total of 18 full-scale specimens were tested under reversed cyclic loading. The results revealed that the strength and energy dissipation capacities of a wooden shear wall can be significantly increased by inserting teak and padauk strips into the grooves between planks and beams. Furthermore, the simplified calculation method proposed in this study can be used to calculate the strength of both reinforced and unreinforced wooden shear walls with satisfactory agreement.

Phantasmagoric Venues from the West to the East: Studies on the Great Exhibition (1851) and the Taiwan Exhibition (1935)

Abstract This research focuses primarily on the Taiwan Exhibition (1935) with particular reference to its archetype, the Great Exhibition (1851). Through these, this paper considers the concepts and appearance of world exhibitions. It also discusses how they became a spatial venue to show ″modernity″ and ″colonialism″ in the nineteenth and early twentieth centuries. It starts with a description of the history and concepts of world exhibitions, and follows with a discussion of modernity and colonialism. Since the nineteenth century, world exhibitions have been regarded as the most meaningful invention of ″modernity″. These not only present the exhibition of commodities, but also reflect the turning point in industrialization. However, camouflaged by the cover of modernization, world exhibitions essentially revealed the ideologies of imperialism and colonialism. Although postdating the Great Exhibition by almost eighty years, this essay will suggest that the Taiwan Exhibition, the greatest exhibition held in Japanese colonial territories, conveyed the same ideologies of modernity and colonialism. It seems that there are unexpected similarities between these two events in completely different times, 1851 and 1935, and places, the west and the east.

In-situ Evaluation Of Timber Roof Structures Of Historic Buildings

Condition assessment is an important step before repairs of timber structure. In the past, the experienced master carpenters carried out these works in Taiwan. This paper addresses the inadequacy of the traditional evaluation method, and proposes a new methodology to evaluate a roof structure by taking into account the structural performance. The method can be divided into three steps, first the visual inspection was conducted to record necessary information for further structural studied. Secondly, the structural analysis of the trusses was carried out in order to obtain the stresses in members. Comparing the resultant stress under loading with allowable stress, safety factor in each member was calculated. Finally, the unsafe and suspect members are designated for further nondestructive testing - the drill resistance. After considering the structural performance of the roof structure and condition in each member, the members that cannot meet the requirement will be found and recommended for replacement. Furthermore, the proper minimum section of each member that should be replaced is also proposed in this paper.

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.