鋼骨圓弧切削梁柱接頭之耐震行為研究

Abstract

美國加州北嶺地震對抗彎鋼構架造成極大損害，甚多梁柱接頭並未發揮其韌性以消散地震能量即已脆性斷裂，對傳統式梁翼全滲透銲與梁腹鎖螺栓接頭型式必須全面檢討與改善。因此，本研究乃製作四組實尺寸試體，為梁腹鎖螺栓梁翼全滲透銲型式，梁翼近柱面處以圓弧切削，探討圓弧切削梁柱接頭之極限彎矩強度與韌性行為。梁翼全滲透銲接使用韌性衝擊值較佳之銲材，並遵循銲接預熱程序，以改善銲接品質。實驗設置乃使梁端承受反覆荷重。實驗結果顯示此型式之接頭可提供優良且穩定之極限彎矩強度與韌性能力，且因其設計簡單，施工容易，確實為改善傳統式接頭有效且經濟之方式。最後並建議圓弧切削接頭之切削設計流程與施工細部，提供實際工程使用，落實研究成果，以期有所貢獻於工程實務。

The wide spread brittle fractures occurred at the steel moment-resisting frame connections were observed after the 1994 Northridge earthquake. The observed damage prevented the welded beam-to-column connections from the intended inelastic behavior to resist earthquake ground shaking. Numerous researches were, then, undertaken to improve the behavior of such bolted web-welded flange connections. This research summarized the testing investigation results of the reduced beam section connections. An experimental research was conducted to investigate the ultimate flexural strength and ductility performance of reduced beam section (RBS) connections. A total of four full-scale specimens with radius-cut RBS were fabricated. The complete joint penetration groove weld between beam flange and column flange was constructed using high toughness weld metal. Electrode E7018 with high Charpy V notch value was used in the full penetration weld. Another feature was the removal of beam bottom flange backing bars. The specimens were tested under cyclic loads that were achieved by applying increments of stroke to the cantilever beam end by a hydraulic actuator. To prevent out of plane deformation of the beam, lateral bracing system was provided. Experimental results demonstrated that radius-cut RBS connections possessed sufficient flexural strength as well as excellent ductility. The plastic rotation of the beams could reach 3% and even higher than 4%. The design procedure and details for sizing the radius-cut RBS connection were suggested.