Cyclic Behavior of Link-to-Box Column Connections for Steel Eccentrically Braced Frames

• Main Authors: ChuiHsin Chen, 陳垂欣
• Other Authors: KehChyuan Tsai
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/58818511864203058687

碩士 === 國立臺灣大學 === 土木工程學研究所 === 88 === Many of the design and welding conditions responsible for the poor performance of moment frame connections in the Northridge earthquake are also presented in the link beam-to-box column connections in the steel eccentrically braced frames (EBFs) in Taiwan. During a severe earthquake, the force and deformation demands imposed on the link-to-column connections in the EBFs are substantially greater than those at the moment connections. A large number of experimental investigations on the performance of weld moment connections have been conducted in the US after the Northridge earthquake. However, it is still very lacking in experimental data on the performance of link-to-column connections in EBFs. This research aims at investigating the cyclic performance of shear link-to-box column connections using the construction practice adopted in Taiwan. There are six specimens and divided into two different link length categories. Two specimens are designed with the link length of (S-Series), and the other fours of (M-Series). In each series, two different link beam web-to-box column connection details are tested. One is connecting the beam web to the shear tab by fillet welds (F-Series), the other is connecting the beam web to the column by groove welds (G-Series). There are two FM-Series specimens using an improved weld access hole details. Test results indicate that the maximum plastic link rotation of S-Series specimens is 0.08 radian, and the maximum strain hardening factor is as high as 1.8. These results suggest that both the code prescribed strength factor of 1.5 and the rotational capacity of 0.09 radian are not conservative. One of the beam web of the G-Series specimens was prematurely buckled near the column. The effects of the erection bolt holes on the local buckling of the beam web suggest that attaching the beam web to the shear tab is preferable. The maximum plastic rotational capacity of the M-Series links is only slightly greater than 0.04 radian. And the link rotational capacity of the specimens using an improved access hole details is about 0.06 radian. Test results suggest that the code prescribed rotational capacity of 0.09 radian should be properly reduced. In addition, it is found from the tests that the M-Series beam outside of the link yielded. It is suggested from the analyses and tests that the moment gradient and the critical sections in the link and the beam outside the link be carefully evaluated using the rigid end zone techniques. This is especially important when the brace-to-beam connection is not fully restrained. Test results suggest that further research on the design and construction of reliable link-to-box column connection details for severe seismic applications are urgently required.