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  • 學位論文

電熱熔渣銲道及梁翼板偏心對SM570M-CHW鋼梁柱接頭耐震性能影響

Seismic performance of SM570M-CHW steel beam-to-column joints with eccentricity among electroslag welding, diaphragm and beam flange alignment

指導教授 : 蔡克銓

摘要


國內外建築高度愈來愈高,高強度鋼的使用有一直增加的趨勢。而SN系列鋼材之最高標稱拉力強度僅有490MPa,因此本研究採用SM570M-CHW鋼延續鄭元良等人(2011)及吳忠哲(2016)進行高強度鋼之梁柱接頭子結構試驗,稱為ESW元件拉伸試驗。因箱型柱以柱內橫隔板傳遞梁翼板之力量,其銲接法常採用效率較高之電熱熔渣銲接(Electro-Slag Welding, ESW)。若因為剪力板銲接位置產生誤差,或箱型柱兩側之梁深不同且差異不大,使柱內橫隔板只能放置一片於兩梁翼高程之間,均造成梁翼及柱內橫隔板高程不同,梁彎矩將使電熱熔渣銲道接柱翼處產生應力集中,若電熱熔渣銲亦有偏心,則會增加ESW接柱翼處之破壞的可能。本研究利用Kanvinde與Deierlein在2004年所提的破壞預測模型,探討SM570M-CHW鋼柱在相同材料梁翼及ESW有偏心的情況下之破壞行為。 先用有限元素模型探討以ESW元件模擬梁柱接頭的可行性後,本研究使用SM570M-CHW高強度鋼製造以Box500×500×28mm接200×28mm之梁翼板組成的ESW元件試體。透過超音波檢測(UT)判斷ESW偏心方向並變化梁翼板偏心,以探討偏心情況下梁柱接頭ESW附近的耐震行為,並使用前述之破壞預測模型對ESW元件模型進行破壞時機預測並與實驗結果比對。實驗及分析結果證明,當柱翼板與梁翼板厚度相同時,梁翼若與柱內橫隔板在不同高程上的垂直偏心量超過一個柱翼板厚度,會使ESW接柱翼處產生無預警之脆性破壞。 本研究為了探討柱翼板厚度變化對ESW接柱翼處破壞的影響,以梁翼板、橫隔板及柱翼板皆為28mm之分析模型是否產生破壞為基準,進行柱翼板厚度改變且梁翼偏心隨柱翼板厚度變化的破壞預測分析,結果顯示柱翼板變厚確實可延後ESW接柱翼處之破壞時機,且本研究建議梁翼與橫隔板高程不宜有偏心量超過四分之三個柱翼板厚度,以避免ESW接柱翼處之脆性破壞。

並列摘要


Tall buildings are getting taller and taller in the mega cities all over the globe. The need of using SM570M-CHW high-strength steel for building constructions in Taiwan is increasing. In order to transfer the beam moment, diaphragms at the beam flange elevations are often welded into the built-up box column using the electro-slag welding (ESW). However, the elevations of the diaphragm, the ESW and the beam flange may not be perfectly aligned. This could be caused by the fabrication error or the slight difference of the depths of two beams framing into the column. The misalignment in beam flange and diaphragm, with or without the eccentricity of ESW, may lead to the brittle fracture due to stress concentrations near the ESW to column flange heat affected zone (HAZ). This study uses the damage prediction model proposed by Kanvinde and Deierlein to investigate the damage potential of ESW component specimens using SM570M-CHW steel with the eccentricity between the beam flange and the ESW. The Abaqus model analysis results are compared with the experiment observations. The ESW component was constructed from a SM570M-CHW steel 500×500×28mm box column with 200×28mm beam flanges. The ESW eccentricity was measured using ultrasonic tests (UT), specimens with various eccentricities between the beam flange and the diaphragm were constructed. The damage prediction models are applied to predict the critical strength and displacement of the ESW components test results. Experiment and analysis results suggest that the eccentricity between the beam and the diaphragm must be no greater than three fourth of the column flange thickness in order to prevent the brittle fracture at the HAZ. The analytical results with varying column thickness indicate that increasing the column flange thickness reduces the abovementioned fracture potential effectively.

參考文獻


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