配置外置預力鋼腱之預力混凝土橋梁施工後長期的變形行為影響橋梁結構的安全性及使用性，預力損失的預測是預力混凝土橋梁設計的重要工作之一。本研究旨在探討外置預力預鑄節塊箱梁在施完預力後之長期混凝土應變變化及相關預力損失，同時利用ACI 209、CEB-FIP MC78與CEB-FIP MC90預測混凝土應變，並探討溫度造成之軸向變化。
本研究以對高雄港聯外高架橋新生路北段第四單元(U4)為例，進行預鑄箱梁節塊的長期應變監測，且預估有效預力，並與設計值比對。
在預力損失評估中，P14-P15跨橋梁在施預力後1100天的內置預力損失為1130~1880 kgf/cm2，約佔初始預力的7%~11.61%；外置預力損失為1140 kgf/cm2，約佔初始預力的7.9 %，兩者均在設計容許值以內。
每日早晚的平均溫差約5~6℃左右，溫度對節塊水平軸向造成約43×10-6之應變，相當於混凝土溫度膨脹係數為8.5~10×10-6/℃。混凝土箱梁因季節變化造成的軸向應變變化約為100×10-6左右。整個橋體單元在正常的日夜溫差下相對最大膨脹水平位移與大氣的最大溫差比值為 1 mm/℃~2 mm/℃，相當於5~10×10-6/℃。
關鍵詞：預力損失；箱型梁；溫度效應；鉛心橡膠支承墊

SUMMARY
Long-term deformations of precast segmental box girder with external tendons usually influences safety and serviceability of bridge structures, and the prediction of prestress losses is one of the main factors considered in the design of bridges. The effect of the temperature on the bridge is also a significated factor. This thesis aims at studying the long-term strain and prestress losses of precast segmental box-girder of Kaohsiung Port. Using the design code predictions of ACI 209, CEB-FIP MC78 and CEB-FIP MC90 for concrete strain of box girder, the long-term effective prestressing force study the effect of the temperature changes on axial strain of the bridge are also studied. With experimental monitoring of Long-Term strain of Precast Segmental Box Girder on Kaohsiung Port Viaduct, this thesis aims to predict effective prestress and compared with designed value.
In the evaluation of pretress losses, the box-girder in span P14-P15 generated 1130~1880 kgf/cm2 internal prestress losses, accounting for 7%~11.61% of the initial prestress and 1140 kgf/cm2 external prestress losses, accounting for 7.9% of the initial prestress for 1100 days after pressing. The average temperature change day and night has about 5~6 ℃, which is 43 ×10-6 concrete strain of box girder and corresponds to 1~2 mm/℃ longitudinal movement at LRB of the 5 span unit.
Keywords: "prestress losses";"box-girder";"temperature effect";"lead rubber bearing"

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