本研究將結構用SN490B鋼材放入高溫爐加熱至900ºＣ後，以空氣冷卻和水中冷卻來模擬火害後可能發生之兩種降溫情形，並製作未受火害、火害後空氣冷卻、火害後水中冷卻三組各兩支反覆載重用試棒，每組試棒再分別進行固定應變及漸增應變不同應變歷程的反覆載重試驗，藉以瞭解SN490B鋼材於高溫火害後可能的反覆載重之行為與求取其相關硬化參數。試驗結果顯示：未受火害試棒與氣冷試棒出現循環硬化之現象，且氣冷試棒之降伏應力折減16.75%；水冷試棒則出現循環軟化之現象，且水冷試棒之降伏應力提升47.62%。此外，本研究使用非線性有限元素軟體，在相同梁柱斷面尺寸條件下，建立五種國內常見梁柱接頭數值模型（即：普通梁柱接頭、蓋板與側板補強梁柱接頭、圓弧式與梯形變斷面式切削梁柱接頭），並導入反覆載重試驗所得之硬化參數，進行五種國內常見梁柱接頭受高溫火害後之反覆載重實驗數值模擬。數值模擬結果顯示：由於氣冷後鋼材強度略微下降，補強與切削之氣冷梁柱接頭數值模型梁柱接頭之梁於柱面所提供之抗彎強度將低於原未受火害前梁於柱面之標稱塑性彎矩值(Mf)，但仍可以滿足AISC對於特別抗彎構架梁柱接頭在變形與撓曲強度之兩項規定；而各組水冷之梁柱接頭數值模型，皆於梁柱銲道處發生斷裂破壞，無法使梁柱接頭發揮預期之塑性變形能力，已無法符合AISC對於特別抗彎梁柱接頭構架之規定。

In this study, the structural steel SN490B was heated to 900℃, and then was cooled down by air and water respectively to simulate two kinds of cooling situations for steel structures after fire. Three groups of round bar specimens, including non-fire damaged group, air-cooling group and water-cooling group, were manufactured for cyclic loading test. The two specimens in each group were tested by constant-strain and increased-strain cyclic loading histories respectively to understand the possible cyclic behaviors of high-temperature fire damaged SN490B steel and to acquire the related hardening parameters. The test results showed that cyclic hardening occurred in the non-fire damaged and air-cooling steel and the yield stress of the air-cooling steel decreased 16.75%. Cyclic softening occurred in the water-cooling steel and the yield stress of the water-cooling steel increased 47.62%. Besides, this study also developed the nonlinear finite-element models for five common beam-to-column connections, i.e. traditional connection, cover-plate connection, side-plate connection, radius-cut flange profile connection and tapered flange profile connection, in Taiwan. The hardening parameters acquired from the previous cyclic loading tests were substituted into the nonlinear finite-element models to perform the numerical simulations of the cyclic loading experiments for the five common beam-to-column connections after high-temperature fire. The numerical simulation results showed that the beam flexural resistance at the column face for each air-cooling connection was lower than the nominal plastic moment at column face (Mf) of each associated non-fire damaged connection for the reason of slightly decreased strength of air-cooling steel, but still could meet the two AISC deformation and flexural strength requirements for beam-to-column connections in special moment frames. All the water-cooling beam-to-column connections fractured at the beam-to-column welds, and could not meet the AISC plastic deformation requirement for beam-to-column connections in special moment frames.

ABAQUS HTML Documentation, “User’s Manual,” Dassault Systèmes Simulia Corp., Providence, RI, USA.

Bruneau, M., Uang, C.M. and Whittaker, A., Ductile Design of Steel Structures, McGraw-Hill,( 1998).

Chen, S.J., Yeh, C.H. and Chu, J.M., “Ductile Steel Beam-to-Column Connections for Seismic Resistance,” Journal of Structural Engineering, ASCE, Vol. 122, No. 11, pp. 1292-1299, (1996).

Engelhardt, M.D., and Sabol T.A., “Reinforcing of steel moment connections with cover plates benefits and limitations,” Engineering Structures,Vol. 20, Issues 4-6, pp. 510-520, (1998)

Engelhardt, M.D., Winneberger, T., Zekany, A.J. and Potyraj, T.J., “Experimental Investigation of Dogbone Moment Connections,” Engineering Journal, Vol. 35, No. 4, pp. 128-139,(1998).

Smith, C.I., Kirby, B.R., Lapwood, D.G., Cole, K.J., Cunningham, A.P. and Preston, R.R., “The Reinstatement of Fire Damaged Steel Framed Structures,” Fire Safety Journal, Vol. 4, Issue 1, pp. 21-62, (1981).

Hopperstad, O.S., Langseth, M. and Remseth, S., “Cyclic Stress-Strain Behaviour of Alloy AA6060, Part I: Uniaxial Experiments and Modelling,” International Journal of Plasticity, Vol. 11, Issue 6, pp. 725-739, (1995).

AISC Seismic Provisions for Structural Steel Buildings, American Institute of Steel Construction, Chicago, Illonois, (2010).

FEMA Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings, FEMA-350, Federal Emergency Agency Management,Washington, DC, (2000).

中華民國材料科學學會，「鋼鐵材料手冊」，科技叢書（1998）。

方朝俊，「火害對耐火鋼構件銲接及栓接行為之影響」，碩士論文，國立台灣科技大學，台北（2000）。

林志宏，「火害後鋼鐵材料微巨觀行為探討」，碩士論文，國立台灣工業技術學院營建工程技術研究所，台北（1997）。

林克強、莊勝智、張福全、張柏彥，「台灣典型鋼梁與箱型柱採梁翼切削或梁翼加蓋板抗灣接頭之破壞模式」，鋼結構耐震設計與分析研討會論文集，國家地震中工程研究中心研究報告（NCREE-08-037），台南（2008）。

林群洲，「肋板補強鋼骨箱型柱梁柱接頭之耐震行為」，碩士論文，國立交通大學土木工程學系，新竹（2002）。

周民瑜，「常見結構用鋼材火害後機械性質之研究」，碩士論文，國立成功大學土木工程學系，台南（2008）。

王士銘，「火害後梁柱接頭銲接區拉力實驗之研究」，碩士論文，國立成功大學土木工程學系，台南（2011）。

蕭雅柏，「構造用金屬材料多向循環負載與異向性研究」，博士論文，國立台灣大學土木工程學系，台北（2000）。

吳家慶，「削切蓋板鋼骨梁柱接頭之耐震行為研究」，碩士論文，國立交通大學土木工程學系，新竹（2005）。

饒智凱，「鋼骨梁柱梁翼內側加勁補強接頭之耐震行為研究」，碩士論文，國立交通大學土木工程學系，新竹（2007）。

鄭瑋，「實尺寸複合梁鋼構架高溫火害行為之數值模擬」，碩士論文，國立成功大學土木工程學系，台南（2011）。