- 學位論文
鋼及玻璃纖維橋面格柵板力學行為及試驗研究
Mechanical Behaviors and Tests of Steel and Glass Fiber-Reinforced Polymer Grating Decks
摘要
本研究嘗試將國內目前救災用之便橋橋面板以重量較輕格柵板取代，以達到全程只須以人力方式即可進行組裝的可攜式簡易便利橋梁設計。為了了解兩種不同材料橋面格柵板的力學行為及傳力機制，本研究透過實尺寸結構試驗測試、理論分析與有限元素軟體ABAQUS (2010)來對於兩種不同材料的橋面格柵板 (鋼橋面格柵板及玻璃纖維橋面格柵板)進行分析，以釐清此兩種橋面格柵板在位移及傳力狀況上是否存在差異，以作為日後工程初步設計的參考指標。 為了探討橋面格柵板的力學行為，本研究根據AASHTO (2007)對此兩種橋面格柵板分別進行了單向加載試驗及疲勞載重試驗。於單向加載試驗結果中顯示，鋼橋面格柵板橫桿因勁度太小，以致板整體撓曲勁度貢獻僅來自於載重施加處底下的主桿；而玻璃纖維橋面格柵板因橫、主桿斷面大小雷同且排列較密，造成玻璃纖維橋面格柵板在抵抗外力時，其板有效寬度比鋼橋面格柵板大得許多；而在疲勞載重試驗結果中顯示，鋼橋面格柵板在歷經五萬次反覆載重後並無任何顯著材料疲勞現象發生,然而玻璃纖維橋面格柵板則有大約8%的勁度流失。 而在理論分析中，為了改善前學者 (Timoshenko and Krieger,1959)對於玻璃纖維橋面格柵板撓曲勁度矩陣的嚴重高估現象，本文也嘗試提出另一種等效撓曲勁度矩陣評估方法，並搭配古典連續板理論來進行分析。從分析結果中顯示，本文所提出的方法不旦能彌補前學者(Timoshenko and Krieger,1959)在玻璃纖維橋面格柵板最大位移評估上的不足，且對於鋼橋面格柵板最大位移評估表現也尚可接受。此外為了探討有限元素分析的可靠性，本研究也使用ABAQUS有限元素軟體來對於兩種橋面格柵板進行分析及參數研究。在分析結果中，其ABAQUS分析結果與理論及試驗結果相符，而在參數研究結果中則顯示橋面格柵板的撓曲勁度貢獻絕多來自於主桿，因此若想將橋面格柵板在受到力量下的最大位移最小化，最佳的調整方法為對於橋面格柵板主桿間距作適度的調整。
並列摘要
For the purpose of developing a newer deck system with portable, reusable and suitable capabilities for ease of transportation using manpower, this study attempts to replace the current temporary bridge deck system by grating deck system. So in order to providing a better understanding of grating deck behaviors (Steel grating deck and GFRP grating deck), a full-scale experimental testing, analytical and numerical analyses have been involved by this study. In the experimental testing, based on the AASHTO 2007, two different type of grating decks were subjected to two different type of loading protocols, the first one is static load test, and the second is fatigue load test. From the result of static load test shows that the secondary bars of steel grating deck were unable to spread the force effectively due to its cross-section are too small if compared to its main bars, however, the situation of GFRP grating deck were be completely different. Despite the deformation of steel grating decks are always small than the deformation of GFRP Grating decks, but in the point of the effective width of decks (Load-transfer ability), the effective width of GFRP grating decks are larger than the steel grating decks all the times. In the fatigue load test, the steel grating decks were not have any significant loss in deck stiffness throughout 50000 cycles of cyclic loading in the range of 2 kN to 20 kN, However, the GFRP grating decks was about 8% stiffness loss found after the fatigue load applied. In the theoretical analysis, we try to use the Classical Plate Theory combined with Timoshenko & Krieger’s Method (1959) to analyze the responses of two grating decks. This method shows satisfying result in steel grating deck, but very poor result in GFRP grating deck due to the centroid of all bars in GFRP grating deck are not in the same plane. So to fix this problem, this study tries to propose another new method to improve the overestimation or underestimation of Timoshenko & Krieger’s Method (1959) in GFRP grating deck. The result shows that the Classical Plate Theory combined with new proposed method success to fix the problem and get quite well result in both two specimens. Besides, this research also uses the finite element software ABAQUS to analyze the grating decks behaviors and compare the results with testing results which is proved similar. In the parametric study, the parametric study indicates that the most significant influence on the maximum deflection at the center of deck is the spacing of main bar, followed by the number of main bar, and last is the spacing of secondary bar.