Browsing by Author "Tsai, Keh-Chyuan"

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Evaluating performance of post-tensioned steel connections with strands and reduced flange plates
(2006-07-25)
Chou, Chung-Che
;
Chen, Jun-Hen
;
Chen, Yu-Chih
;
Tsai, Keh-Chyuan
;
土木工程學系
The seismic performance of post-tensioned steel connections for moment-resisting frames was examined experimentally and analytically. Cyclic tests were conducted on three full-scale subassemblies, which had two steel beams post-tensioned to a concrete-filled tube (CFT) column with high-strength strands to provide recentring response. Reduced flange plates (RFPs) welded to the column and bolted to the beam flange were used to increase the dissipation of energy. Test results indicated that (1) the proposed buckling-restrained RFP could dissipate energy in axial tension and compression, (2) the subassemblies could reach an interstorey drift of 4% without strength degradation, and (3) buckling of the beam occurred towards an interstorey drift of 5%, causing a loss of the strand force, the recentring response, and the moment capacity. A general-purpose non-linear finite element analysis program (ABAQUS) was used to perform a correlation study. The behaviour of the steel beam under both post-tensioning and flexural loadings was compared to the test results and predictions. Copyright (C) 2006 John Wiley & Sons, Ltd.
Seismic rehabilitation performance of steel side plate moment connections
(2010-01-01)
Chou, Chung-Che
;
Tsai, Keh-Chyuan
;
Wang, Yuang-Yu
;
Jao, Chih-Kai
;
土木工程學系
Moment connections in all existing steel building located in Kaohsiung, Taiwan were rehabilitated to satisfy seismic requirements based oil the 2005 AISC seismic provisions. Construction of the building was ceased in 1996 due to financial difficulties and was recommenced in 2007 with enhanced connection performance. Steel moment connections in the existing building were Constructed by groove welding the beam flanges and boiling the beam web to the column. Four moment connections, two from the existing steel building were cyclically tested. A non-rehabilitated moment connection with bolted web-welded flanges was tested as a benchmark. Three moment connections rehabilitated by welding full-depth side plates between file column Face and beam flange inner side were tested to validate the rehabilitation performance. Test results revealed that (1) the non-rehabilitated existing moment connection made by in situ welding process prior to 1996 had similar deformation capacity its contemporary connection specimens made by laboratory welding process, (2) all rehabilitated moment connections exhibited excellent performance, exceeding a 4% drift Without fractures of beam flange groove-welded joints, and (3) presence of file full-depth side plates effectively reduced beam flange tensile strain near the column face by almost half compared With the non-rehabilitated moment connection. The connection specimens were also modeled Using the non-linear finite element computer program ABAQUS 10 further confirm the effectiveness of the side plate in transferring beam moments to the column and to investigate potential Sources of connection failure. A design procedure was made based oil experimental and analytical Studies. Copyright (C) 2009 John Wiley & Sons, Ltd.
Seismic self-centering steel beam-to-column moment connections using bolted friction devices
(2008-04-10)
Tsai, Keh-Chyuan
;
Chou, Chung-Che
;
Lin, Chi-Lon
;
Chen, Pei-Ching
;
Jhang, Sheng-Jhih
This paper first presents the force-deformation relationship of a post-tensioned (PT) steel beam-to-column connection constructed with bolted web friction devices (FDs). This paper then describes the test program conducted in the National Center for Research on Earthquake Engineering, Taiwan, on four bolted FDs and four full-scale PT beam-to-column moment connection subassemblies using the FDs. Tests confirm that (1) the hysteretic behavior of four bolted FDs is very stable, (2) the friction coefficient between the steel plate and the brass shim is about 0.34, (3) the proposed force-deformation relationships reasonably predict the experimental responses of the PT connections under cyclically increasing deformations up to a beam peak rotation of 0.05 rad, and (4) the decompression moments do not degrade as beam cyclic deformations increase. Copyright (C) 2007 John Wiley & Sons, Ltd.