火害下合成梁之撓曲行為

Abstract

鋼材具有強度高自重輕之優點，但鋼材溫度升高時其強度即會大幅減少，所以火害對於鋼構造會造成嚴重之影響。本研究以試體試驗方法探討合成梁受防火被覆保護下在高溫下之撓曲行為，並建立合理之分析方法。在試驗方面，本研究共進行三組試體之試驗，試驗參數為施加在試體上之防火被覆厚度及試體有否受到載重。探討不同防火被覆厚度之試體在加溫試驗中之撓曲行為及有無載重之影響。分析方法是建立一套分析合成梁在高溫下撓曲行為之模型，利用試驗時獲得之數據，對合成梁進行熱膨脹及材料力學性質折減之分析，計算合成梁在加溫試驗時之撓度，驗證分析方法之準確性。由試驗結果發現，載重與否對鋼梁之溫度影響不大；另外防火被覆越厚者，使鋼梁之溫度上升較慢，從而使試體之撓曲度較小。分析結果顯示，分析方法能合理分析特定情況之試驗行為。

Steel does not only provide high intensity, but it also posses light weight. However, its intensity decreases while temperature rises, and fire does highly affect the structure of steel. The objective of the research is to use specimen testing method to investigate the behavior of composite beams with fireproof coating under high temperature , so as to build up reasonable analysis methods. Totally, three specimen tests are introduced in this study. Testing parameters are considered for the thickness of the fireproof coating coating specimen and the loading conditions of the specimen. Besides, it also tries to understand the flexural behavior of different thicknesses of fireproof coating specimen under rising temperatures and the affection to it without loading. In the study, a model is built up to analyze the flexural behavior of the composite beam under high temperature, then take advantage of the output data to analyze the thermal expansion and the reduction of the mechanical properties of materials of the composite beam, and calculate the deflection of the composite beam under rising temperature, as to verify the accuracy of the analysis method. From the testing result, it can be seen that loading does not bring that much affection to steel beams. In addition to that, the thicker the fireproof coating coating on beams, the slower the temperature rises and the smaller the deflection of the specimen.