預力混凝土梁預力之非破壞檢測技術試驗研究

Development of a Non-Destructive Testing Technique for Identification of Prestress Force in Concrete Beams

魏星池(Hsing-Chih Wei)

指導教授 ： 張國鎮

國立臺灣大學/工學院/土木工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201701724

摘要

面對橋梁老化問題，須對橋梁全生命週期進行有效管理，掌控橋梁劣化及損壞趨勢。預力橋廣泛應用於公路、鐵路等交通建設中，然而預力橋梁在其服務使用年限中，會遭遇不同劣化原因，如混凝土潛變、鋼鉸線鬆弛、腐蝕等因素造成預力損失，影響預力橋梁之耐久性，嚴重時可能損及其安全性。目前現有檢測技術多為破壞性檢測方式，實際應用上較難以執行，因此本研究嘗試發展一套非破壞性檢測方法用以檢測預力梁之預力。
本研究透過放大係數法及其演變方法應用於預力梁之預力檢測，由試驗得到之變位與必要之參數，求得構件之軸力。本研究透過七米矩形混凝土梁與十五米實尺寸混凝土梁驗證本方法於檢測預力梁之預力效果。由試驗結果顯示當具有較明顯二階效應條件時，如預力越大或變位越大時更易獲得準確之預力識別結果。且試驗結果亦顯示試驗施加集中力需小於軸力的十分之一條件才能得到符合理論基礎之試驗結果。
由本研究試驗結果，建議試驗之橫向集中力不宜過大，以及量測位置建議以變位最大處為佳，直線配置鋼腱之預力梁在滿足以上條件時可獲得準確之預力識別結果，當試驗橫向力更大時或拋物線配置鋼腱之預力梁，其結構行為可能受鋼腱與套管作用等因素影響，造成非預期之行為，此部分有待後續研究深入探討。

關鍵字

預力梁 ； 預力檢測 ； 變位量測 ； Ｉ型梁 ； 直線鋼腱

並列摘要

Facing the aged problem of bridges, it is necessary to administrate the full lifecycle of bridges. Prestressed bridges are widely applied in highway and railway. However, prestressed bridges encounter a variety of deteriorating reasons and affect the safety, like creep of concrete, relaxation of tendon…etc.
This study uses magnification factor method to develop a non-destructive testing method to identify the prestress force in the concrete beams. Using the deflections to get the axial force. In this study, verifying the method by the experiments of 7m and 15m prestressed beams. The results show that the identifications are well under the II-order effect is significant. The results also show the applied concentrated force couldn’t be larger than one tenth of prestress.
According the results of this study, it suggests the applied concentrated force shouldn’t be too large and the measured position is better at the position occurs the maximum deflection. For the prestressed beams with the straight tendon, it could get accuracy identifications under above conditions. For parabolic shape tendon case, it may be affected by some unknown reasons and need detail study in the future.

並列關鍵字

prestressed beam ； prestress force identification ； deflection measurement ； I-shape beam ； straight tendon

參考文獻

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