Abstract:Although Indonesians have for many years used wood to build traditional houses, currently it is difficult to find new traditional houses made from wood. Since wood is too expensive for local people, concrete becomes the major construction material instead. However, wood is considered a sustainable material that is eco-friendly, recyclable, and has less of an environmental impact than concrete. In this study, an innovative and cost efficient waste-wood composite structure was proposed with the intention of fulfilling local demand for the construction of traditional wooden houses, as well as supplying a sustainable and cost-efficient wooden product in the construction sector. Four small pieces of waste wood connected with steel nails or self-tapping screws were assembled into a rectangular waste-wood composite, serving as secondary beam, column, or brace. These waste-wood composites are considered recyclable and low-cost, and provide an alternative solution for local people that achieves an affordable and sustainable construction system. The assembled wood components were tested under single shear in order to clarify the structural performance of connection and the failure modes. The comparison of the experimental results and predicted results showed that the predicted strength is considered in a conservative manner for further application. In addition, the cost estimation and comparison between a solid wood structure and the waste-wood composite structure indicated that the price of the waste-wood composite structure is potentially competitive and cost-efficient for the local people, which was optimistic for future development.

In Taiwan, most of the existing historic wooden buildings built in the Japanese colonial period have become culturally important. These properties preserve the historical atmosphere and culture of local communities. Unfortunately, some of these buildings have been abandoned or have suffered serious damage during earthquakes; and, others have not been well maintained. The conservation and retrofitting of these historic wooden buildings have recently become valued and recognized by authorities. Some of these buildings have been retrofitted, becoming exhibition galleries, restaurants, or even local landmarks. However, changes in the functions of the building have resulted in some safety issues, such as additional fire loading or demolished shear walls. In this paper, adaptive reuses of these retrofitted buildings are discussed based on a field investigation. Factors that directly influence the structural safety are emphasized, and a potential issue affecting these factors -the lack of professional education and experience -is also discussed.

Hybrid structures known as timber–steel composites (TSCs) have been extensively studied due to their potential use as alternative construction materials that can satisfy demands related to sustainability. In addition to load capacity, fire resistance is a major consideration regarding the extensive use of TSCs. In this study, 12 specimens were tested using a glulam timber material covering cold-formed steel at the center. Specifically, the TSCs were fabricated from two timber blocks and an I-shaped steel core assembled using dowels or glue as a major structure. In order to use additional timber as a fire protection layer to protect a major structure by its charcoal produced after being burned, an additional timber with 5 cm in thickness was used to cover the major structure. The 1-h fire testing of TSC following the ISO 834-1 standard was applied, in order to achieve the potential application for a 4-story timber building. The results showed that temperatures at the steel flange increased by more than 300 °C for the final 5 min in 10 out of the 12 TSC specimens, indicating that the fire protection provided by the timber structure was not sufficient. The charcoal layer surpassing the extra timber was originally set and entered the steel structure of the TSC, which was expected to retain its physical qualities after a fire. Methods for evaluating the charring properties, based on the conventional method for wood and the standard specification set by Eurocode 5, were used to assess the structural degradation of TSCs. The conventional assessments showed a divergence from the actual performance of TSCs. Such variations demonstrated the limitations of models for conventional wood in assessing the structure of a TSC. A realistic assessment was conducted to expand knowledge related to this composite under destructive processes and provide fire reference values for the practical implementation of TSCs.

Due to improvements in the use of recyclable materials in construction, timber-steel composite (TSC) beams demonstrate high potential for future construction. In this study, a proposed simulation modeling, which was adopted from the simulation modeling of a timber I-shape composite, was applied to estimate the initial stiffness of TSC beams. The strength of each beam could be determined once the initial stiffness was estimated. In addition, a series of experiments were performed to examine the accuracy of the proposed simulation modeling, including the effects of different shapes of steel members, fasteners, and applying and not applying a dowel connection. The results indicated that the simulation modeling could adequately determine strength at a deflection of 1/360 of the span. The ratio of difference between the experimental results and the simulation modeling results was less than 10% if a dowel connection at the web was applied. However, the ratio of difference reached 26% and 24% in the TSC beams without a dowel connection at the web that were fastened with screws and nails at the flange, respectively, revealing the importance of applying a dowel connection at the web. Moreover, the strength of the TSC beams with a dowel connection at the web that were fastened by screws was approximately 15% higher than that of TSC beams without screw fasteners. In conclusion, the proposed simulation modeling can provide designers with a method for estimating the initial stiffness and strength of TSC beams within a deflection of 1/360 of the span, supporting the future application of TSC beams in construction.

Wooden Composite is assembled with semi-circular waste wood by fastener, in order to provide local Indonesian affordable construction components potentially. Considering wooden composite, the withdrawal resistance affect the shear resistance ability under short-term lateral load, therefore withdrawal test is carried out in this study. The withdrawal test shows that steel nail and self-tapping screw work properly to attach each specimen when considering the assembly of wood composite. The observation results indicate different types of fasteners affect the test result significantly. For the fasteners connected with hardwood, the test result shows higher withdrawal resistance than softwood, both using self-tapping screw and steel nail. Based on the test results, there are 3 main failure modes that is concluded, which are fastener failure, material failure, and conditional failure. The test result of self–tapping screw also shows that this kind of fastener is able to withstand 3.5 times stronger than steel nail.