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Title: | 高強度鋼纖維混凝土開口剪力牆往復載重行為研究及建議設計流程 The Study on Cyclic Behavior and Suggested Design Process of High Strength Steel Fiber Reinforced Concrete Walls with Opening |
Authors: | 何奕親 Yi-Ching Ho |
Advisor: | 廖文正 Wen-Cheng Liao |
Keyword: | 開口剪力牆,鋼纖維混凝土,橋接效應,構件韌性,軟化壓拉桿模型, shear walls with opening,steel fiber concrete,bridging action,toughness of member,softened strut-and-tie model, |
Publication Year : | 2023 |
Degree: | 碩士 |
Abstract: | 臺灣位於環太平洋地震帶上,因此發生地震的頻率相當頻繁,且由於人口稠密,集合式住宅相當常見,若因地震造成建築物倒塌,受其影響之人口將不計勝數。住宅建築為了滿足使用性設置許多剪力牆體,且為配合採光或用途需求許多是具有門型或是窗型開孔。這些剪力牆雖具有極高之側向強度和勁度,在耐震能力上能提高整體結構之勁度,但在過去震損之調查中也同時發現是地震中震損較嚴重的構件,其破壞經常集中在開孔左右兩側之垂直牆段上,造成整體結構雖未崩塌,但其使用機能已不復存在,民眾亦無法信任其安全性而繼續居住。
近年來,高強度混凝土開始被廣泛使用,國內的規範也逐漸更新並採用,然而該材料雖具有良好的抗壓能力,其破壞模式卻會變得較為脆性,為了維持足夠的結構韌性,需在剪力牆這類不連續區域配置大量圍束鋼筋,而這也造成施工上綁紥鋼筋之不易。 添加鋼纖維於高強度混凝土之中能延緩脆性破壞,由於鋼纖維混凝土的橋接效應與應變硬化效應能有效抑制裂縫寬度之擴張,因此能大幅減少橫向鋼筋以解決施工上的問題,也能消除現今開口剪力牆因裂縫造成的安全疑慮。根據本研究群歷年針對結構不連續區域的研究,包含梁柱接頭與深梁的試驗,透過研究結果發現使用於高強度混凝土中添加鋼纖維可提高構件之抗剪強度其強度點後之韌性,但其力量傳遞機制與基礎軟化拉壓桿模型仍有待近一步研究。 因此本研究承接前一年之研究執行五座高強度鋼纖維混凝土剪力牆試驗,以開孔之有無、開孔型式、牆體鋼筋比、邊界柱主筋量、開孔補強筋配置及開孔兩側之垂直牆段寬度作為試驗參數,欲透過試體強度變形行為和裂縫發展之觀察,得到開孔剪力牆極限剪力與撓曲強度並釐清鋼纖維之效益,修正預測模型並提出建議設計流程做為未來設計之參考。 Reinforced concrete walls are commonly used in residential building. Due to functional purpose, opening of windows and doors are required for non-loadbearing walls. Although the existance of shear walls can improve the stiffness of the structure in terms of seismic capacity, it is the component with serious seismic damage during earthquakes. In the earthquake damage investigation, it was observed that the damage was often concentrated on the vertical wall sections beside the opening, which leads to people distrust the safety of walls. High strength reinforced concrete has been utilized in modern high-rise buildings. Howerver, as the material has higher compressive strength, it become more brittle. In order to maintain certain ductility in high shear demanding area such as shear walls, lots of shear reinforcement are required in design code, which leads to steel congestion and construction difficulties. Studies show that by adding steel fiber into concrete, brittle behavior can be improved and cracks can be restrained effectively because of the bridging action steel fiber provides across microcracks in the matrix, thereby adding steel fiber into concrete is able to replace certain amount of transverse reinforcement so as to attatin a better construction workability as well as eliminate the safety concerns caused by cracks in shear walls with opening. Based on research results conducted on discontinuity regions such as deep beams and beam-column joints, using steel fiber reinforced concrete (SFRC) can promote toughness and shear strength of the components, replacing huge amount of transverse reinforcement. While the benefits of using SFRC in structural discontinuities are known, its force transmission mechanism in shear walls remains to be clarified. In this study, five SFRC walls specimens were carried out to investigate the effect of the types of opening, the ratio of web shear reinforcement, the amount of stirrups in the boundary elements and the strengthening reinforcement of opening. By observing the crack development of the specimen, as well as the strength and deformation behavior, it is concluded that the adding of steel fibers can effectively replace half amount of stirrups in the boundary element and strengthening reinforcement of opening. A model is also proposed to include the tensile strength provided by the steel fiber in the horizontal tensile capavities for equilibrium, which determine a more reasonable height of shear element. The shear strength result are also more accurate than predicted strength by TEASPA. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88807 |
DOI: | 10.6342/NTU202302462 |
Fulltext Rights: | 同意授權(限校園內公開) |
Appears in Collections: | 土木工程學系 |
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