臺灣博碩士論文加值系統

本研究探討高溫下橫梁對邊跨大梁受力行為之影響。研究中，首先比較美國鋼結構協會(AISC)及歐洲規範(Eurocode 3)常溫及高溫設計規範中撓曲強度設計方法上之差異，並利用有限元素套裝軟體進行數值模擬之結果比較兩規範在撓曲強度預估上之差異。接著，進行抗彎矩構架中邊跨大小梁試體之高溫試驗及數值模擬。最後，利用經與試驗驗證之邊跨大小梁分析模型進行參數分析，探討大小梁斷面深度比、小梁深厚比及載重大小對大小梁破壞模式、變位與溫度關係、防火時效及構架失穩時間之影響。
研究中另定義臨界溫度為撓曲桿件變位到達日本JIS耐火設計規範建議之高溫下撓曲桿件變形量(L2⁄800d)；失穩溫度為結構發生失穩現象時對應之溫度，以便於比較高溫下各參數對大梁受力行為之影響。
研究結果發現，常溫下依據AISC設計規範計算之鋼梁撓曲強度較Eurocode 3之預估強度高近三成。高溫下，兩規範與數值模擬之結果在AISC高溫鋼梁設計規範之差異在6~20%之間；而Eurocode 3高溫鋼梁設計規範之差異約為三成。
高溫試驗發現，邊跨大小梁在高溫下之破壞模式分別有大梁側向扭轉挫屈、局部挫屈、小梁側向扭轉挫屈及剪力挫屈及螺栓脫牙等。小梁與大梁具有相同斷面深度時，因加載點變位發展較快，構架失穩溫度較低。
參數分析結果顯示，結構臨界溫度與失穩溫度隨著大小梁斷面深度比之增加而增加；小梁斷面深厚比越大時，可能發生腹板剪力挫屈，導致失穩現象提早發生；載重大小較低時，可以得到較長之防火時效。

The influence of floor beam to the main girder in the side span under fire condition has been examined in this research. At first, the differences of AISC and Eurocode 3 in design methods for flexural strength of steel beams at both room and elevated temperature are examined. The flexural strength calculated following these two specifications are also compared with the results from the numerical simulation.
Then, the experimental tests accompany with the numerical simulation are carried out to examine the fire performance of the girder-beam system in the side of a moment-resisting steel frames. Finally, parametric studies are conducted to investigate the influence of the floor beam to the failure modes, the deformation, the fire resistance and the collapse behavior of the girder-beam system by using the verified numerical models. The parameters considered in this study are the depth ratios of beam to girder, depth-to-thickness ratios of the floor beam and load ratio.
The critical temperature, the temperature that the displacement of the girder and the floor beam reach the limitation specified in JIS (L^2⁄800d), and the collapse temperature, the girder and the floor beam lost their instability, have been defined as used as the basis to compare the performance of the girder-beam in the side span.
The results of this study found that the flexural strengths calculated by AISC specification is up to 30% higher than those determined by Eurocode 3 at room temperature,. At elevated temperatures, the strength difference between the AISC and the numerical results is between 6 and 20%；while strength difference between Eurocode 3 and numerical results is up to 35%.
Based on the experiment results, it is found that the failure modes of the girder-floor beam in the side span of the moment-resisting frame exposed to fire include lateral-torsional buckling, local buckling, shear buckling of web plate and bolt off the tooth.
The collapse temperature of the girder-beam system decreases if the floor beam shares the same depth with the main girder due to a larger displacement.
The results of parameter analysis show that the critical temperature and collapse temperature increase with the increase of the depth ratio of beam-to-girder. With a larger depth-to-thickness ratio, the shear buckling of the floor beam is likely leads to the premature failure of the system. With a smaller load, the fire resistant of the girder-beam system can be enhanced.

目錄
摘要...I
Abstract...II
致謝...IV
目錄...V
表目錄...VII
圖目錄...VIII
第一章、緒論...1
1.1研究動機與目的...1
1.2文獻回顧...2
1.3研究方法及內容...4
第二章、既有規範回顧...5
2.1現行鋼梁常溫規範之回顧與比較...5
2.1.1 AISC常溫鋼梁設計規範...6
2.1.2 Eurocode 3 一般情況下常溫鋼梁設計規範...7
2.1.3 Eurocode 3熱軋或銲接斷面之常溫鋼梁設計規範...8
2.2 現行鋼梁高溫規範之回顧與比較...11
2.2.1 AISC高溫鋼梁設計規範...11
2.2.2 Eurocode 3 高溫鋼梁設計規範...12
2.4 小結...18
第三章、鋼結構大小梁高溫試驗...29
3.1試驗規劃與設計...29
3.2試驗結果...38
3.2.1破壞模式...40
3.2.2小梁斷面之影響...45
3.3小結...48
第四章、高溫下大小梁受力行為模擬...49
4.1數值模型之建立...49
4.2數值模擬驗証比較...51
4.2.1高溫材料性質之選擇...51
4.2.2破壞模式與變形之比較...52
4.3參數分析...58
4.3.1大小梁斷面深度比之影響(dbeam/dgirder)...58
4.3.2小梁深厚比(dtw)之影響...62
4.3.3載重大小之影響...66
4.4小結...70
第五章、結論與建議...71
附錄...72
參考文獻...78

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