本研究採用非線性之纖維元素法 (Fiber element method)建立考慮二次彎矩效應之矩形填充型鋼管混凝土柱 (Concrete-filled steel tube, CFT)的軸壓雙向彎矩互制曲線。本研究採用的纖維元素法經由假設柱身之變形函數後，能考慮二次彎矩效應，並計算能施加於柱端之最大彎矩，由分析不同軸壓力所對應之彎矩強度可建立考慮二次彎矩效應之軸壓彎矩互制曲線。多組矩形CFT柱之軸壓彎矩試驗數據用來驗證纖維元素法分析CFT柱之合理性，並藉由參數研究探討纖維元素法、AISC-LDFD與ACI之適用範圍，結果發現纖維元素法在分析CFT柱受單向彎矩時能準確的計算彎矩強度，AISC與ACI則於柱長較短的案例較能計算出合理的彎矩強度。本研究將不同寬厚比、材料強度與有效柱長的CFT柱互制曲線歸納為一般化的互制公式，做為建立互制曲線之建議公式。

This study presents nonlinear fiber element method determine the axial load-biaxial bending moment interaction curves of concrete filled steel tubular beam-columns (CFT). Second-order effect is considered by assuming the deflected shape of the CFT beam-columns. Determine the maximum moment at the column ends for different axial compression loads by fiber element analysis method, the interaction curves are constructed and second-order effect is considered. Analytical results are verified by comparing with the experimental results. For the cases that the fiber element analysis method, AISC-LRFD and ACI can accurately predict the flexural strength, the parameters of the cases are studied in this research. The predicted results of fiber element analysis method show good agreement with the uniaxial bending tests. The AISC-LRFD and ACI is suitable predict the flexural strength of short CFT beam-columns. To construct the general interaction equations, interaction curves of CFT beam-columns with different width-to-thickness ratio, material strength and column lengths are considered in the equations.

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