Translated Titles

Feasibility Study of Applying the Deflection Measurement Technology to Identify the Prestress Force in Pre-stressed Concrete Beams





Key Words

空間構架 ; 預力檢測 ; 預力梁 ; 位移量測 ; 預力損失 ; space frames ; prestress force identification ; pre-stressed beams ; deflection measurement ; prstress losses



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Chinese Abstract

為對橋梁全生命週期進行有效管理,應有效掌握各個橋梁構件損壞及劣化之 趨勢及原因。預力橋在城市道路、鐵路及高速公路均有廣泛應用,且在進行此類 橋梁設計過程中,通常根據現有規範及理論公式來計算所施加之預應力值,而在 設計使用年限內,預力梁建設完成後,鋼絞線鬆弛、混凝土潛變、鋼絞線及錨頭 之摩擦、錨頭移位及溫度變化均可能造成預力損失。因此,為了有效控制預力梁 使用狀態,預力梁之預力檢測則成為必然。 本研究首先以空間構架試驗進行理論驗證,以試驗數據結果判斷文中所用非 破壞軸力檢測方法之可行性。隨後以加載橫向載重及量測橫向位移之方式來對預 力梁進行軸向應力識別,並將其應用於預力構件識別預力變化之檢測技術研發, 於研究初期分別以預力箱型鋼梁及預力混凝土梁試體進行試驗。試驗採用後拉法 施加預力之方式加載預力,量測預力梁承受橫向載重下特定點位之位移,同時考 量構件之挫屈載重公式來推估梁所承受之軸力值,即預力值。並將預估預力值與 安裝於預力梁端部之荷重計量測值進行比較,由初步試驗結果來驗證檢測方法之 可行性,進而規劃進一步深入研究及擴大試驗試體規模。

English Abstract

To administrate the full lifecycle of bridge beams, it is necessary to grasp the reasons of damages in bridge members. Pre-stressed beams are broadly applied in the urban, railway and highway bridges, during the design process, prestress forces are decided through existing norms or theoretical formula. Within their serviceability life, after the construction, many factors such as relaxation of tendons, shrinkage and creep of concrete, friction between tendons and tendon ducts, anchorage slip and ambient temperature can lead to the change of the applied pre-stress forces. So, in order to control the status of pre-stressed bridges, the identification of prestress force is inevitable. This study conducted the theoretical testify in space frames to make a clear judge of the feasibility of these non-destructive methods mentioned in this paper. Subsequently, by using displacements measured after applying a vertical load in the mid-span of the beam, the identification of prestress force can be made on pre-stressed steel box beam and pre-stressed concrete beam, respectively. Post-tensioning method is considered during the experimental tests. Axial force, which is prestress force, can be estimated by using displacements measured in certain sections and the formula of axial buckling load. Comparing estimated axial force with existing axial force, which is measured by a load cell at one end of the beam, it is possible to verify the feasibility of axial force identification proposed in this study and then, enlarge the size of specimen and plan for further study in the near future.

Topic Category 工學院 > 土木工程學研究所
工程學 > 土木與建築工程
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