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The investigation of the DOL (Duration of Load) effect to the timber structure in consideration of the influence of environmental conditions

考虑环境条件影响的木结构 DOL（荷载持续时间）效应研究

基本信息

批准号：
11460082
负责人：
IIJIMA Yasuo
金额：
$ 7.1万
依托单位：
Akita Prefectural University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

项目摘要

The purpose of this research is to establish the method of designing the timber structure where reliability is guaranteed over a long period of time. In the member of a timber structure, when physical partial damage of wood accumulates with the increase in load time also under comparatively mild atmosphere conditions, an on-the-strength performance falls gradually. DOL (Duration of Load) factor is the allowable stress adjusting method for such influence.However, in Japan, annual change of environmental factors, such as temperature and humidity, changes greatly with areas. Therefore, introduction of this system which made only physical external force the index may produce the difference by the environment of an area in the resistance or deformation of structure.Moreover, by the Limit State Designing method which becomes the mainstream of the future timber structure designing method, both load and resistance of structure are dealt with as a random variable according to the estimated usable period of a structure. However, the relation between time progress and on-the-strength reduction is not clear.Therefore, research on the following three items was done in this research.1.Experimental investigation of DOL effect to timber structure in consideration of influence of environmental conditions2.The influence prediction to strength degradation by biological attack3.Creation of simulation model of degradation of strength required for establishment of Limit State Designing Method Consequently, it was suggested that the function model in consideration of probability could express the tendency of the strength degradation of members by DOL and biological attack. The effect by the environmental factor is considered that the further analysis is required although judged as what the influence cannot disregard from the collected data.

本研究的目的是建立木结构设计的方法，在很长一段时间内的可靠性得到保证。在木结构构件中，当木材的物理部分损伤随着载荷时间的增加而累积时，即使在相对温和的大气条件下，强度性能福尔斯也逐渐下降。DOL（Duration of Load）系数是考虑这种影响的容许应力调整方法，但在日本，温度、湿度等环境因素的年变化因地区而异。因此，引入这种仅以物理外力为指标的体系，可能会使结构的抗力或变形因地区环境的不同而产生差异，而成为未来木结构设计方法主流的极限状态设计法，则根据结构的预计使用年限，将结构的荷载和抗力都作为随机变量处理。然而，时间进展与强度减少之间的关系并不明确。因此，本文主要研究了以下三个方面的内容：1.考虑环境条件影响的木结构DOL效应试验研究2.生物攻击对强度退化的影响预测3.建立极限状态设计所需的强度退化仿真模型方法提出了考虑概率因素的函数模型，该模型能较好地反映生物损伤和生物损伤引起的构件强度退化趋势。环境因素的影响被认为是需要进一步分析的，尽管从收集的数据中判断这种影响是不可忽视的。