- 學位論文
螺牙錨栓應用於混凝土之工程特性
Screw Anchor Engineering Properties for Concrete Use
摘要
本研究主要了解螺牙錨栓工程實務上的應用特性。主要研究錨栓為M8和M10螺牙錨栓與M8位移式膨脹錨栓，安裝埋設深度分別為70mm、80mm與50mm進行研究，而M8螺牙錨栓也會以埋設深度50mm進行比對分析。試驗項目分為抗拉抗剪之基本試驗、模擬地震的週期性抗拉抗剪試驗、混凝土邊緣效應的抗拉抗剪試驗、群錨的間距影響之抗拉抗剪以及錨栓氫脆化特性。試驗用混凝土以未開裂混凝土進行試驗，設計強度有210kgf/cm2、280 kgf/cm2與525 kgf/cm2，主要依照ASTM E488、ACI355.2和ETAG001規範進行試驗與分析，試驗後混凝土會以鑽心抗壓試驗了解其實際抗壓強度，依ACI公式將錨栓回歸至設計強度進行分析。 M8螺牙錨栓埋設深度70mm與50mm於極限抗拉強度比為1.68(36.33kN/21.60 kN)，所以埋設深度越深強度越高，而M8螺牙錨栓與M8膨脹錨栓在埋深50mm極限抗拉強度比為0.93(21.60kN/23.02kN)，螺牙錨栓前端因斜切形成不完全牙，導致承載力略低膨脹錨栓；而M8螺牙錨栓與M8膨脹錨栓極限抗剪強度比為1.72(25.55 kN /14.88 kN)，經金相觀測比較和熱處理調質相關；M8螺牙錨栓與膨脹錨栓在週期性抗拉與抗剪荷載，於50%、37.5%、25%極限荷載後，進行基本抗拉與抗剪得知殘餘極限強度，螺牙錨栓和位移式膨脹錨栓大於基本抗拉對照組之極限抗拉強度80%，依ACI 355.2評估為第一類錨栓，故推估錨栓在承受週期性荷載後仍能提供有效的耐震能力。M10螺牙錨栓於邊距效應試驗結果中，試驗邊距c與埋設深度hnom(c1)之比值為2(160mm/80mm)，抗拉與抗剪極限強度以與基本試驗相仿，故距邊距愈遠強度影響愈少；在群錨間距抗拉試驗結果中，試驗間距s與埋設深度hnom之比值為3 (240mm/80mm)，與基本抗拉極限強度之比為1.97，因群錨(雙錨)與基本(單錨)強度比值已很接近2倍，故s/hnom比值於3以上較不會互相影響。群錨間距抗剪試驗以邊距80mm為設定邊距c1，而試驗間距s與設定邊距c1之比值1到4的試驗結果中，試驗的統計曲線並無漸緩的趨勢，故在s與c1比值4倍以上可能還是會有影響；M10螺牙錨栓於525 kgf/cm2混凝土，於氫脆試驗環境100小時中，可能氫脆攻擊機制效果不夠，導致過程中鋼材並沒有產生斷裂，進一步的研究仍有待繼續。
並列摘要
The objective of this study is to investigate the engineering properties of concrete use post installed mechanical anchors. M8 and M10 screw anchors and M8 undercut expanded anchor were used in the studied. Tensile and shear strength, and seismic tensile and shear test of single anchor, and edge effect and spacing effect of multiple anchors under tension and shearing loading conditions were investigated. Un-cracked concrete with nominal compression strength of 20.6 MPa and 51.5 MPa were used. ASTM E488 standard test methods, ACI 355.2 standard, and ETAG 001 guideline were followed in the test program and analyses. Concrete strength of each test was normalized according to ACI code in the analyses. Nominal installation depths of 70 mm, 80 mm, and 50 mm were used for M8 and M10 screw anchors, and M8 undercut expanded anchor. Installation depth of 50 mm for M8 screw anchor was also used for comparison studied. Preliminary brittleness of concrete screw anchor was also investigated. Because the test screw anchors are made from harden steel, the average tensile strengths for the M8 screw anchor were 35.46 kN and 20.86 kN for 70 mm and 50 mm embedment with concrete cone breakout failure mode, respectively. 70 mm embedment was found to be appropriate for the test M8 screw anchor. The average tensile strength was 22.32 kN with 50 mm embedment for the expansion anchor. 50 mm embedment seems to be sufficient for the test M8 sleeve expansion screw. Similarly, due to the M8 screw anchors is made from harden steel, the average shear strength of the screw anchor was 25.90 kN and is much higher than that, 14.87 kN, for the M8 sleeve expansion anchor. No reduction on the residual tensile strength and shear strength were observed for both M8 screw and expansion anchors after subjected to ACI specified seismic loadings. Both anchors can be classified as Type 1 anchors under tension and shear seismic loading conditions. The results of the edge effect test showed that condition with edge distance of 160 mm with C/hnom ratio of 2.0, the strengths for tension test and shear test are all similar to those for the reference conditions. The spacing effect test anchors were installed with edge distance of 80 mm. The tensile strength for the spacing of 240 mm was almost double to that of reference condition. In addition, the shear strength with the spacing distance of 320 mm was about twice of that for single anchor condition. The suggested installation spacing ratios s/hnom with edge distance of 80 mm condition subjected to tension load and shear load are 3.0 and 4.0, respectively. Preliminary brittleness study was conducted for the M10 screw anchor with the nominal compression strength 51.5 MPa concrete. Further study is continued.