Welded end‐slot connection and debonding layers for buckling‐restrained braces

Abstract

SUMMARY The debonding mechanism has a significant effect on the performance of a buckling‐restrained brace (BRB). In this paper, a method for estimating the compression strength adjustment factor for any given BRB core strain is presented. Experimental investigations were conducted on four BRBs to examine the efficiency of four different debonding materials in reducing the difference between the cyclic peak compression and tension. Test results indicate that chloroprene rubber is very easy to install and very effective in minimizing the difference between the compressive and tensile capacities. The excellent performance of 13 full‐scale welded end‐slot BRBs (WES‐BRBs) is illustrated through experiments. Cyclic loading test results of a 12.5‐m long jumbo WES‐BRB reveal that its peak compressive strength exceeds 16,800 kN and its maximum core strain reaches 0.035. All WES‐BRBs show satisfactory performance with a very stable hysteresis response, modest peak compressive to tensile strength ratio, and very predictable axial stiffness. These specimens sustain a cumulative plastic deformation of greater than 400 times the yield deformation. The hysteresis responses can be satisfactorily predicted by using a two‐surface plasticity analytical model. Advantages of the welded end‐slot connections are also presented through a discussion on the effects of the BRB yield region length ratio on the effective stiffness, the yield story drift, and the core strain level. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of non‐moment braced frame seismic deformations on buckling‐restrained brace end connection behavior: Theoretical analysis and subassemblage tests

“…The frame tests by Lin et al [15], Chou et al [16], and Palmer et al [17] showed that in-plane frame action force at the beam-column-gusset interface was observed. These findings [15][16][17][18][19][20][21] all highlighted the negative effect of braced frame seismic deformations on the performance of BRB connection zones. The gusset plate design considering the combined effect of brace action and frame action forces was investigated theoretically and numerically [18][19][20].…”

“…The subassemblage tests by Tremblay et al [14] showed that BRB end rotation would cause additional inplane flexural stress on BRB casing. The gusset plate design considering the combined effect of brace action and frame action forces was investigated theoretically and numerically [18][19][20]. The frame tests by Lin et al [15], Chou et al [16], and Palmer et al [17] showed that in-plane frame action force at the beam-column-gusset interface was observed.…”

Seismic retrofit of reinforced concrete frames using buckling‐restrained braces with bearing block load transfer mechanism

“…Based on previous experimental and analytical studies, the effective elastic stiffness K eff of a typical BRB in a structural frame can be computed from three springs connected in series [21] as: ) 468 671 25 35 397 530 394 483 398 521 90 Note: f y and F y are steel yield strengths; f u and F u are steel tensile strengths; f c is concrete or mortar compressive strengths. Based on previous experimental and analytical studies, the effective elastic stiffness K eff of a typical BRB in a structural frame can be computed from three springs connected in series [21] as: ) 468 671 25 35 397 530 394 483 398 521 90 Note: f y and F y are steel yield strengths; f u and F u are steel tensile strengths; f c is concrete or mortar compressive strengths.…”

“…Practical methods of utilizing BRB technology are well developed. In comparison with butt-spliced or lap-spliced BRBs, slot-spliced BRBs have more compact joints, greater BRB end stability [3,23,24,26] and higher fatigue life because of increased yield region length [21,25]. In comparison with butt-spliced or lap-spliced BRBs, slot-spliced BRBs have more compact joints, greater BRB end stability [3,23,24,26] and higher fatigue life because of increased yield region length [21,25].…”

Seismic design and testing of buckling‐restrained braces with a thin profile

“…The letter 'W' stands for the welded BRB end details ( Figure 9a); meanwhile, letters 'R' (Figure 9b), 'F' (Figure 9c), and 'C' (Figure 9d) stand for the specimens using the pinned end connections with the ribbed, flanged, and cover-plated joint sections, respectively. In addition, in order to investigate the effects of the debonding layer thickness on the local bulging failure, the chloroprene rubber (CR) debonding layer [11] thickness in the R25G1-250-IN and F25G4-160-IN were 1 mm and 4 mm, respectively. The second last letter in the IDs stands for the applied loading type, which is described later.…”