鋼管混凝土柱構件設計公式在AISC規範中係以純鋼構公式為主要依據，利用轉換係數將混凝土之貢獻轉換為鋼結構強度。而在AISC-2005規範中，其鋼管混凝土採用塑性應力分配法及應變諧合法兩種方法執行抗壓強度之計算。本文利用斷面應力分段切割疊加之方法，對應AISC-2005之塑性應力分配法及應變諧合法執行計算，並比較兩種方法之差異性。本研究僅以方形和矩形斷面為例，並將其斷面計算轉換成Excel之電腦執行程式，因此輸入相關之斷面性質與材料強度，即可取得此斷面之P-M圖，探討鋼管混凝土柱構件之理論與設計強度。 The design strength of concrete-filled tubes (CFT) is being investigated and evaluated based on the current methods as specified in the AISC specifications. The AISC Specification applies the steel column formulas with the use of coefficients for transforming the concrete into steel to determine the CFT design strength. In AISC-2005, the design strength of CFT is being evaluated through the use of two approaches including the plastic stress distribution and strain compatibility methods. This study used both the plastic stress distribution and strain compatibility methods to calculate the design strength of CFT, and compare the design strengths using these two methods. The calculation is proceeded with the numerical approach by using the developed software program and the P-M curves are plot. The P-M curves are plot for both the rectangular and square sections. The illustrated examples are furnished to demonstrate the step-by-step procedure to obtain the CFT design strength based the AISC Specification.