鋼骨箱型柱偏心梁柱接頭之耐震行為

Abstract

國內的鋼結構設計偶有因建築師空間規劃上之需求，造成梁柱的偏心接合。本研究以實尺寸梁柱接頭試驗，探討箱型柱梁柱接頭偏心接合時之力學行為與補強型式。實尺寸實驗共規劃四組偏心接合之梁柱接頭，包括一組未補強型式及三組補強之梁柱接頭試體。試驗結果發現，未補強偏心接頭試體塑鉸機制未能形成，僅有些微之塑性行為，最終破壞於偏心側之梁翼全滲透銲道處；在偏心接合之不利條件下，梁柱接頭之韌性行為不穩定。採雙肋板補強之試體，雖已改善梁翼全滲透銲道兩側之集中應力，最終仍在下梁翼全滲透銲道處拉裂。另兩組單肋板補強試體中，考慮全滲透銲道兩側之高韌性需求，加銲側向垂直加勁板於梁翼板兩側以降低該處之應力集中現象；適當設計之側向加勁板能明顯的提升梁柱接頭之韌性能力。此外，柱內橫隔板之銲接優劣對梁柱接頭影響甚鉅。研究結果顯示梁柱接頭之偏心易導致接頭行為的不穩定，設計時應避免梁柱接頭的偏心。

Eccentric connections between welded box column and steel beam are not uncommon in the steel moment-resisting buildings. This research aims to investigate the seismic behavior of eccentric connections by full-scale test. Four eccentric connections, that included one unreinforced connection and three reinforced connections were tested under cyclic loading. The test results showed that unreinforced connection was unable to develop the required ductile behavior because of brittle fracture at the edge of groove weld. The specimen, strengthened with two vertical rib plates at the edges of the beam flange, can reduce the stress concentration at the edges of the CJP welds. Nevertheless, failure was initiated from the CJP cracks occurred at the bottom beam flange. The rest specimens were strengthened with the side plates and a single rib to attenuate high strain demand at the borders of flange groove welds. Significant improved moment-plastic rotation behavior was obtained from these two specimens. Moreover, the performance of connections depends on the integrity of the welding to join the diaphragm. It is concluded that the presence of the eccentricity in the connection would conduce the unstable behavior of the joint.