近年來，全世界強烈地震發生的次數越來越頻繁，而且發生的地震規模有明顯增大之現象，強震來襲時，既有建築物是否能繼續屹立不倒，早已成為人類極度關切的問題，因此近年來有關建築結構耐震能力評估之研究，如雨後春筍般地蓬勃發展。台灣位處環太平洋地震帶，高層建築物又大都使用鋼結構，在當前國內有關鋼建築結構耐震能力評估模式尚未完善之際，鋼建築結構耐震能力分析便成為一項重要研究課題。 本文以20層規則韌性抗彎矩鋼建築結構為例，先採用擬靜力法進行結構分析設計及應力檢核，再以側推分析進行耐震能力評估，並分析比較採用不同FEMA塑鉸、不同豎向地震力分佈、不同塑性轉角、不同柱梁彎矩強度比、不同梁斷面尺寸、不同柱斷面尺寸和經濟型斷面及搭配不同普通同心斜撐、韌性同心斜撐與偏心斜撐系統，對此韌性抗彎矩鋼建築結構耐震能力之影響，藉以瞭解不同影響因子對此類鋼建築結構耐震能力之影響，以及一般耐震能力評估模式在評估此類建築結構耐震能力之適用性。研究結果顯示，NCREE評估算式所算得的耐震能力較符合原設計值，其中又以層間位移轉角2%所對應的耐震能力較接近原設計值，極限地震力所對應之耐震能力則有高估之現象。本文之研究成果可供工程實務界及學術界參酌引用。 In recent years, the strong earthquakes have occured frequently and their Richter scale has increased significantly in the world. Whether the existing buildings can continue to maintain undamaged or not has become an extrem concern of human. Therefore, the studies on the seismic capacity assessment have mushroomed in recent years. Taiwan is located in the Circum-Pacific seismic zone and there are so many high-rise buildings constructed of steel. As the seismic capacity assessment for steel building structures are not perfect for the time being, the study on seismic capacity analysis of steel building structures has become an important issue. A 20-story steel building structure with moment-resisting ductile frame is selected as a basic structure in this thesis. The basic building structure is analyzed and designed by quasi-static analysis method first. The pushover analysis method is used to assess the seismic capacity of this basic building structure then. The seismic capacity of steel building structures with different FEMA plastic hinge, different distribution of vertical seismic force, different plastic rotation, different bending- strength ratio between column and beam, different beam section size, different column section size, economic section size selection and with different ordinary concentrical braces, different buckling restrained braces and eccentric braces are also investigated in this thesis. The main purpose of these investigations is to realize the different effects of these factors on the influence of structural seismic capacity and the suitability of general seismic capacity assessment model for these steel structures. The results have shown that the seismic capacity assessment results based on NCREE formula are more satisfied with the original design value. In particular the seismic capacity corresponding to 2% inter-story drift ratio is closer to the original design value and the seismic capacity corresponding to ultimate strength is overvalued. The results of this thesis are available for engineering practitioners and academics references.