高強度鋼纖維混凝土的力學性質與圍束效應之研究

Study of the Mechanical Properties and Confinement Effect of High Strength Steel Fiber Reinforced Concrete

郭耀仁(Yao-Jen Kuo)

指導教授 ： 廖文正

國立臺灣大學/工學院/土木工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00625

摘要

台灣地狹人稠，都市發展所需的土地資源取得不易，超高樓層建築物逐漸成為未來趨勢。但建築物高度愈高，中低樓層的柱構件也承受愈大的軸壓，若發展高強度混凝土為建築材料，一方面可以減小梁柱斷面的尺寸，增加建築物的使用空間；另一方面，由於建築材料用量減少，又能兼具節能減碳的優點。日本政府在西元1988年到1992年間推行五年期國家型計畫New RC Project，New RC Project主要目的為大幅提高鋼筋混凝土的建築材料的強度，混凝土強度從40MPa提升至120MPa以上，鋼筋降伏強度從420MPa增加至685MPa以上。截至西元2007年為止，日本已有超過500棟以上New RC建築物。
高強度混凝土是極為脆性的材料，位處環太平洋火山地震帶上的台灣而言，建築物梁柱的耐震性能極為重要，對於承受高軸壓的高強度鋼筋混凝土柱，必須提供更多的圍束箍筋才能使高強度鋼筋混凝土柱較具韌性行為，達到耐震的要求。另一方面，高強度鋼筋混凝土柱容易發生早期保護層剝落的現象，造成抗壓強度驟減，大大威脅使用者的安全。許多文獻顯示，藉由添加鋼纖維不僅可以有效預防早期保護層剝落，而且也可以增加高強度混凝土的韌性。
本研究主要探討高強度鋼纖維混凝土的力學性質與圍束效應，目的在了解高強度鋼纖維混凝土中鋼纖維添加量與韌性的關係，進而提出高強度鋼纖維混凝土的韌性的回歸公式，並與高強度鋼筋混凝土柱的箍筋所提供的圍束效能互相比較，以了解鋼纖維所提供的圍束力與箍筋所提供的圍束力的關係。此外，本研究也進行收縮的試驗，了解高強度鋼纖維混凝土的自體收縮與總乾燥收縮是否在合理範圍內。

關鍵字

高強度混凝土 ； 抗壓 ； 圍束 ； 韌性 ； 端鉤形鋼纖維 ； 鋼纖維拉拔 ； 應力-應變曲線 ； 收縮

並列摘要

From 1988 to 1992, the Japanese government carried on a five-year national project, New RC Project, to substantially increase the strength of the construction materials of the reinforced concrete for high rise buildings. The concrete strength rises from 40 MPa to 120 MPa, and the yielding strength of steel bar rises from 420 MPa to 685 MPa. Up to 2007, Janpan already has more than 500 New RC buildings.
Due to brittleness of high strength concrete, much more confinement is needed to improve the ductility and satisfy seismic requirements for high strength reinforced column, particularly under high axial loading demands. Furthermore, early cover spalling trigs substantial compressive strength loss and thus sudden failure occurs. Many studies show that addition of steel fibers can not only effectively prevent the early cover spalling, but also increase the toughness and ductility of high-strength concrete.
This study investigates the mechanical properties and confinement effect of high-strength steel fiber reinforced concrete. The objective is to understand the relationship between the toughness and the volume fraction of steel fibers of high-strength steel fiber reinforced concrete, and proposed the regressive formulation of the toughness of high strength steel fiber reinforced concrete. The confinement efficiency provided by steel fibers or stirrups is also proposed by the regressive formulation of the toughness. In addition, the shrinkage experiments, including measurement of autogenous shrinkage and total drying shrinkage, are conducted to verify the volume stability of high-strength steel fiber reinforced concrete.

並列關鍵字

high-strength concrete ； compression ； confinement ； ductility ； hooked-end steel fiber ； steel fiber pullout ； stress-strain curves ； shrinkage.

參考文獻

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