Performance degradation of glued-laminated timber beams under multi-factor environmental aging and sustained load

IF 2.4 3区 农林科学 Q1 FORESTRY
Xueliang Wang, Xiao Zhang, Mingrong Zhang, Frank Lam, Minghao Li, Zhe Chen
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Abstract

Structural performance of timber buildings can be adversely affected by exposed harsh environment and sustained load. This study investigates bending performance degradation of glued laminated timber (GLT) beams (50 mm × 50 mm × 950 mm) that are exposed to unfavorable environmental conditions. The experiments consider eight scenarios, including various climate cycling periods, duration, and stress levels. Eight groups of GLT beams were exposed to the different scenarios for four stages, then loaded by short-term bending to obtain the MOR and MOE. The results showed that coupling effects of sustained loading and the environmental factors such as UV-light and mist spraying aggravated the pronounced damage on the laminates and gluelines and caused the degradation of strength and stiffness. The highest degradation rate occurred in the first stage. In the relatively mild environments, some performance recovery was observed in the later stages, most specimens exhibited ductile failure accompanied by the significant increase of the ultimate deflection with the exposure time. While in the harsh environments, the MOR and MOE degradation was evident and continuous, more specimens experienced brittle failure, and the increase of the ultimate deflection slowed down greatly with the exposure time. Additionally, the effects of sustained loading period were significantly exacerbated under the harsh environmental conditions, the specimens loaded by less than 50% stress level exhibited the distinguished degradation in 24 days.

多因素环境老化和持续荷载作用下胶合层合木梁的性能退化
暴露的恶劣环境和持续荷载会对木结构建筑的结构性能产生不利影响。本研究研究了暴露在不利环境条件下的胶合层压木材(GLT)梁(50mm × 50mm × 950 mm)的弯曲性能退化。这些实验考虑了八种情景,包括不同的气候循环周期、持续时间和压力水平。对8组GLT梁进行了4阶段的不同工况暴露,并进行了短期弯曲加载,获得了MOR和MOE。结果表明:持续载荷与环境因素(如紫外线照射、雾喷等)的耦合作用加剧了层合板和胶合线的明显损伤,导致层合板和胶合线的强度和刚度退化;降解速率最高的是第一阶段。在相对温和的环境中,后期性能有所恢复,大部分试件表现为延性破坏,极限挠度随暴露时间的增加而显著增加。而在恶劣环境下,试件的MOR和MOE降解明显且持续,脆性破坏较多,且极限挠度随暴露时间的增加幅度大大减缓。此外,在恶劣环境条件下,持续加载时间的影响显著加剧,加载低于50%应力水平的试件在24 d内表现出明显的降解。
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来源期刊
European Journal of Wood and Wood Products
European Journal of Wood and Wood Products 工程技术-材料科学:纸与木材
CiteScore
5.40
自引率
3.80%
发文量
124
审稿时长
6.0 months
期刊介绍: European Journal of Wood and Wood Products reports on original research and new developments in the field of wood and wood products and their biological, chemical, physical as well as mechanical and technological properties, processes and uses. Subjects range from roundwood to wood based products, composite materials and structural applications, with related jointing techniques. Moreover, it deals with wood as a chemical raw material, source of energy as well as with inter-disciplinary aspects of environmental assessment and international markets. European Journal of Wood and Wood Products aims at promoting international scientific communication and transfer of new technologies from research into practice.
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