火害下合成梁撓曲行為之有限元素分析

Abstract

國內廣泛使用鋼結構，於鋼梁上部鋪設鋼承板，以剪力釘連接，後澆製混凝土形成合成梁。本研究以有限元素分析方法研究不同參數對於高溫下合成梁撓曲行為之影響。研究依序為建立分析模型，藉由實尺寸試驗，驗證有限元素模型之正確性；並設定分析參數，包括有無樓板、載重大小與橫斷面溫度分佈等。研究結果顯示數值模型能有效模擬合成梁於高溫下變形行為。參數研究結果得知樓板於溫度較低時，對於撓曲勁度的提供並不明顯；溫度提高後，合成梁材料強度降低，樓板能有效減緩合成梁撓曲變形速率。載重比分析得知施加載重越大時，伴隨著溫度的提高材料強度漸減，促使合成梁提早產生大變形。合成梁橫斷面溫度分佈結果顯示合成梁撓曲變形深受鋼梁上下翼板溫度之差異而影響。

Composite beams formed with steel deck, shear studs and concrete are commonly used in steel buildings. Utilizing the finite element method, this study aims to investigate the effect of parameters on flexural behavior of composite beams at elevated temperatures. The research was conducted by establishing and validating the analysis model by comparing the results with full-scale test results, and setting-up the parameters including the existing or not of the concrete slab, load ratio, and cross-sectional temperature distribution. The results showed that numerical model can effectively simulate the deformation behavior of composite beams in fire. The parametric study demonstrated that the slab could effectively reduce the deflection rate of the composite beams, with decrease of the material strength, at high temperature although the effectiveness was not apparent at lower temperature. The analysis results of load ratio indicated that increasing the applied load, accompanied with the strength decrease due to high temperature, resulted in detrimental deformation of the composite beams. The analysis results of the cross-sectional temperature distribution showed that the flexural deformation of the composite beams greatly influenced by the temperature difference between top and bottom flanges of the steel beam.