正交胶合木(CLT)荷载持续作用效应及影响机理研究

正交胶合木（CLT）作为主要承重材料建造中高层建筑已成为世界木结构行业研究热点和重要发展战略。在发展装配式建筑和中高层木结构建筑背景下，CLT在国内也呈现很好发展趋势。荷载持续作用效应（DOL）是木结构设计中的重要问题，荷载和湿度变化长期共同作用下，CLT特殊构造特征和横向层滚动剪切对CLT力学性能DOL效应产生复杂的影响。针对CLT长期力学性能基础数据和理论不完善，国内关于CLT力学性能DOL效应研究仍为空白，项目从锯材宏观构造,CLT构造特征，温湿度环境和混合结构等角度全面阐明CLT受弯和受剪力学性能DOL效应影响机理，同步采用声发射和DIC系统，揭示CLT构件的DOL破坏机理；分析不同加载方式下CLT构件的DOL效应，建立适合CLT材料特性的DOL模型和DOL系数。项目研究成果将完善CLT材料性能研究，为CLT长期力学性能设计提供基础数据和基本理论依据，促进国内中高层木结构建筑发展。

The research of using Cross-laminated timber (CLT) as structural elements of mid- and high-rise timber building has been the research hotspot and development strategy of timber structure industry in the world. CLT will also has good potential development in China due to the development of prefabricated buildings and mid- and high-rise timber structures. The duration of load (DOL) effect is an important problem in the design of timber structure. Under the long term of load and humidity change, the technical characteristics of CLT and the rolling shear of transverse layers have significant and complicated influences on the mechanical properties of CLT. As the basic data and theory of CLT’s long-term mechanical properties are not perfect, and the DOL effect research on CLT’s mechanical properties in China is still blank, the influence mechanisms of DOL effect in the bending and shear properties of CLT will been studied in this project, which include the cross section macroscopic characteristics of timber, structural characteristics of CLT transverse layer, the configurations of hybrid CLT, as well as the effects of bonding line and the temperature and humidity. The failure mechanism of CLT during the DOL tests will been revealed by the acoustic emission and digital image correlation (DIC) methods. The influences of different loading modes on the DOL effects of CLT will been analyzed. Finally, the new DOL model and DOL coefficient, which suitable for the characteristics of CLT material, will been established. The research results of this project will improve the research on the long-term mechanical properties of CLT, provide basic data and basic theoretical basis for the long-term mechanical properties design of CLT, and promote the development of mid- and high-rise timber buildings in China.