2002 Fiscal Year Final Research Report Summary
The investigation of the DOL (Duration of Load) effect to the timber structure in consideration of the influence of environmental conditions
| Project/Area Number |
11460082
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林産学
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| Research Institution | Akita Prefectural University |
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Principal Investigator |
IIJIMA Yasuo Akita Prefectural University, Institute of Wood Technology, Professor, 木材高度加工研究所, 教授 (10279507)
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| Co-Investigator(Kenkyū-buntansha) |
OKAZAKI Yasuo Akita Prefectural University, Institute of wood Technology, Professor, 木材高度加工研究所, 講師 (70279511)
HIRASHIMA Yoshihiko Nagoya University, Faculty of Agriculture, Professor, 大学院・農学研究科, 教授 (30208821)
NAKAMURA Noboru Niigata University, Faculty of Agriculture, Professor, 農学部, 教授 (30180384)
NAKATANI Hiroshi Toyama Prefectural Forest and Forest-Products Research Center, Section chief, 製品開発課, 課長
ARATAKE Shiro Miyazaki Prefectural Wood Utilization Research Center, The vice-manager, 木材加工部, 副部長
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| Project Period (FY) |
1999 – 2002
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| Keywords | Duration of Load / damage accumulation / degradation of strength / estimated-usable period / Creep / the probability of variables / Limit State Designing method / biological attack |
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| Research Abstract |
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 conditions
2.The influence prediction to strength degradation by biological attack
3.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.
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