The Future and Challenges of Large-scale Wood Structures

• Main Authors: Cheng, Ru-Yun, 鄭如妘
• Other Authors: 王彥博
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/88883787933262657731

碩士 === 國立交通大學 === 土木工程系所 === 104 === In response to global climate changes and worldwide rising awakeness for environment protection, the concepts of green buildings and materials are widely promoted among all countries, with wood structures being highly attractive as a consequence. In early days, wood structures were mostly constructed with logs so that the scale of structures was limited. Advances in wood manufacturing industry have made the erection of large-span wood structures a reality and created opportunities for the development of new construction technologies of large-scale wood structures. This study explores the current status and future on the development of wood structures, including investigation of the structural characteristics of a large arch bridge and discussion of possible challenges in the construction of high-rise wood buildings. In this study, the stochastic subspace system identification (SSI) method was adopted to identify the dynamic characteristics of a large-span arch bridge of woods subjected to pedestrians excitation simulated by moving loads. Under the disturbances of pedestrians in a steady state, the cases with higher sampling frequency prove better in terms of the number of modes identified, accuracy in the estimated damping ratio as well as the MAC values. As the boundary conditions of this wood bridge are mostly hinges, the vibration modes related to the longitudinal direction of the bridge are found difficult to excite, while the high frequencies modes are not excited with less pedestrians on the bridge simultaneously. Therefore, it is suggested to conduct field tests of pedestrian bridges in both rush hour and off-peak time so as to get more insights of the structural characteristics via system identification. On the other hand, the advances and application of Cross-Laminated Timber (CLT) provide the possibility towards the construction of high-rise wood buildings. Nevertheless, comprehensive studies are not yet available in exploring the characteristics of high-rise wood structures in earthquake-protection, fire-proof and wind-resistance. For instances, component tests of CLT wall panels were restricted to the in-plane behavior only, safety and serviceability problems introduced by large deformation and P- effects, as a result, due to the low lateral stiffness nature of wood structures, issues on ductility and deformation control of connectors, fire tests were restricted to timbers alone without the assembly with connectors as a whole, etc. The safety of high-rise wood buildings remains highly uncertain before clarification and exclusion of the aforementioned concerns. The high-rise wood structures to be named of in Europe and North America are located at cities without the threats of earthquakes and typhoons. For countries suffering from those natural hazards like Taiwan, it is not suggested to be overly optimistic on the promotion of high-rise wood buildings.