Seismic Performance of Steel Column-Tree Moment Connections with Tapered Beam Flanges
|關鍵字:||托梁;特殊抗彎構架;抗彎接頭;側推分析;梯度梁翼板;column-tree;special moment frame;moment connection;pushover analysis;tapered beam flange|
With a prospective advantage of better quality control of the shop welding, steel column-tree constructions are widely used in design practice of Taiwan and Japan nowadays. These connections used in the column-tree system are fabricated in the shop by welding short pieces of stub beams to the column. However, brittle fracturing of the column-tree connections was observed during the 1995 Kobe earthquake. The purpose of this study is to develop a new scheme of moment connections for steel column-tree moment-resisting frames. This connection improvement is intended to enhance the ductility of the connection by tapering portions of beam flanges following the seismic moment gradient. A series of the finite element parametric study was conducted to investigate the effect of the taper flange geometry on the connection performance. Numerical analyses revealed that significant yielding spread around the tapered region of the beam and took place away from the column face. Full-scale subassemblage specimens, consisting of a typical pre-Kobe connection and six tapered flange connections, were designed and tested to clarify their seismic performance. Experimental observations demonstrated that the pre-Kobe specimen failed caused by a brittle fracture of the beam flange originated from the toe of the weld access hole, whereas the specimens with the tapered flange connection sustained a sufficient 5% rad story drift angle and resulted in stable energy dissipation. A design procedure of the tapered flange connection, accordingly, is proposed based on the results of the finite element analyses and full-scale connection tests. In addition, pushover analysis of frames with tapered flange connections was carried out. The performance of the tapered flange frames was compared to that of the moment-resisting frames with unreinforced connections. The results of the structural analyses demonstrated that frames with tapered flange connections have stable inelastic performance and satisfied ductility.
|Appears in Collections:||Thesis|
Files in This Item: