本文以單鋼管混凝土(CFT)之材料組成律以及數值模型為基礎，進而應用於圓形斷面雙鋼管混凝土(CFDST)之材料組成律以及數值模型。本文使用非線性有限元素軟體ABAQUS模擬雙鋼管混凝土柱受到純軸柱構件以及雙鋼管混凝土梁-柱(Beam-Column)，並與實驗結果比較。利用模擬方式可得到受到圍束作用所增加之側向圍束壓力(Lateral Confining Pressure)、混凝土強度折減係數(Strength Degradation Parameter)與混凝土軟化參數(Softening Parameter)，將模擬之結果以多變量分析方法計算曲面迴歸，並得到側向圍束壓力、混凝土強度折減參數與混凝土軟化參數建議公式。純軸力柱以內、外鋼管之直徑與厚度比為自變數。梁-柱構件建議公式以施加軸向極限載重百分比、外鋼管之直徑與厚度比與內鋼管之直徑與厚度比為自變數。
由模擬結果與建議公式可以發現在雙鋼管混凝土柱構件中在外鋼管之徑厚比與內鋼管之徑厚比都為較小時可以使得混凝土得到較佳之圍束效果，相同的結果也發生於外鋼管之徑厚比較大與內鋼管之徑厚比較小之組合。換言之，當外鋼管之徑厚比與內鋼管之徑厚都比較大之圍束效果相對較差。
雙鋼管混凝土梁-柱構件中當內徑厚比與外徑厚比保持常數，側向圍束壓力隨著軸向載重比例增加而增加。在較大之外徑厚比與較小之內徑厚比具有較佳之側向圍束壓力。
以AISC規範為基礎將受到圍束作用之混凝土強度與未受圍束作用之混凝土強度代入規範計算軸力強度，考慮受到圍束作用之混凝土強度所計算出之軸力強度較未受圍束作用之混凝土強度所得到之之軸力強度大致上更接近實驗結果。

Proper material constitutive models based on the concrete-filled tube (CFT) for the concrete-filled double skin tube (CFDST) columns and beam-columns with circular cross section are proposed and verified against experiment data using the nonlinear finite element program Abaqus. The proposed equations of lateral confining pressure, strength degradation parameter and softening parameter are depend on diameter-to-thickness of outer tube and diameter-to-thickness of inner tube of column element. The proposed equations are depend on diameter-to-thickness of outer tube, diameter-to-thickness of inner tube and percentage of nominal axial strength of beam-column element.It is shown that CFDST columns can provide a good confining effect for concrete core, especially when the diameter-to-thickness ratios of the outer and inner tubes are small. The CFDST beam-columns can provide a good confining effect for concrete core, when the diameter-to-thickness ratios of the outer is big and the diameter-to-thickness ratios of inner tubes is small. In addition, empirical equations are proposed to predict the lateral confining pressure of the concrete core for CFDST columns. Finally, the axial strengths of the CFDST columns calculated by the proposed formulations are compared with AISC formulations against the experimental data. It shows that the proposed formulations are better than the AISC formulations.

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