採用高強度鋼材梁柱彎矩接頭之耐震行為

Abstract

本研究藉由大尺寸梁柱接頭試體試驗，探討採用高強度鋼材梁柱接頭之耐震行為。高強度鋼板有高降伏比的特性，意謂其韌性較差；因此應用高強度鋼材於梁柱接頭之耐震性能研究有其必要性。本研究進行四組大尺寸梁柱接頭試體之反覆載重實驗，試體為一層樓高柱單邊接半跨距梁之梁柱子結構。第一組試體RBS-QCA為梁翼板圓弧切削型式接頭並搭配常用於國內的雙圓弧銲接扇形開孔，第二組試體WUF-W為未補強梁翼板-腹板銲接型式接頭且採AWS所建議的耐震銲接扇形開孔。第三組試體WF1及第四組試體WF2為擴翼式接頭並搭配常用於國內的雙圓弧銲接扇形開孔。試驗結果顯示，高強度鋼板之降伏強度介於486 至520 MPa間，抗拉強度介於572 至 638 MPa之間，降伏比於81至86% 間。所規劃之四組試梁柱接頭體皆可達5% 弧度的層間變位角與3% 弧度的塑性轉角，滿足國內外耐震韌性需求；僅於試體RBS-QCA與WUF-W中梁翼板靠近全滲透銲處與銲接扇形開孔處有些微裂縫。四組試體皆具優良之韌性行為且無發生脆性破壞。

This research aims to investigate the seismic behavior of beam-to-column moment connections using high-strength steel through large-scale test. High-strength steel is characterized with a high yield ratio (the ratio of yield to tensile strength) which implies a less ductility. Thus, the cyclic behavior of moment connections fabricated by the high-strength steel has to be clarified. In this research, four large-scale specimens were fabricated and tested. The specimens represented a subassembly including a one-story high column between mid-height of the two adjacent stories and a half span beam. The first specimen (RBS-QCA) had reduced beam section with weld access hole in the shape of quarter circular arc. The second specimen (WUF-W) was designed to have welded unreinforced flange-welded web with weld access hole details as specified in AWS (American Welding Society). The third specimen (WF1) and fourth specimen (WF2) had widened beam flange section with weld access hole in the shape of quarter circular arc. Coupon tests of the high-strength steel plates noted that the yield strengths are ranged from 486 to 520 MPa and the tensile strengths are reached 572 to 638 MPa. The yield ratios are ranged from 81 to 86%. The test results showed that all the specimens achieved 5% rad story drift and greater than 3% rad plastic rotation. Although minor cracks occurred at the tip of the beam flange near the penetration groove weld and the root of the weld access hole in the first and the second specimens, the cracks did not propagate. All the specimens successfully develop ductile behavior without brittle fracture and exhibit reliable strength.