Dynamic Response of a Chevron Concentrically Braced Frame

Abstract

Abstract:Large-scale shake table tests were conducted at E-Defense, Japan, to examine the 4 dynamic response of a steel concentrically braced frame. The specimen was a single-bay, single-5 story frame with a pair of square-HSS braces placed in a chevron arrangement. The gusset plates 6 connecting the brace to the framing elements were provided with an elliptic fold line to 7 accommodate out-of-plane rotation of the brace in compression. The specimen was subjected 8 repeatedly to a unidirectional ground motion with increasing magnitude until the braces buckled 9 and eventually fractured. The bracing connections performed as intended; the gusset plates 10 folded out-of-plane and no crack was observed in the gusset plate or in the critical welds. 11Consequently, the test results demonstrated excellent performance of the bracing connections. 12Elastic deformation of the beam prevented the braces from developing their full tensile strength. 13Yielding in the middle of the beam, which was predicted by monotonic loading analysis, did not 14 occur. The specimen response was reproduced by a numerical model using fiber elements. This 15 model was able to predict the occurrence of brace buckling and fracture and thereby, accurately 16 trace the dynamic behavior of the frame. 17

Proposed Methodology for Earthquake-Induced Loss Assessment of Instrumented Steel Frame Buildings: Building-Specific and City-Scale Approaches

“…Figure 1 suggests that there is a strong correlation between the DSFs and story-based EDPs. Same findings hold true for the rest of the shake table experiments that were investigated [24][25][26][27]. …”

“…Hwang and Lignos [22] conducted further validations on the potential use of wavelet-based DSFs for structural damage identifications based on full-scale shake table experiments on steel frame buildings with steel MRFs [24,25] and concentrically braced frames [26,27]. They found that the mapping of a DSF value to a story-based EDP is possible.…”

Seismic Behavior of Chevron Concentrically Braced Frames with Weak Beam

“…In another experimental study, Bubela et al [21] examined incorporating vertical slotted connection in steel chevron braced frame to prevent vertical load transfer to beam through full-scale quasi-static cyclic tests of two specimens. Dynamic response of steel CBF with chevron arrangement and elliptical fold line in gusset plate connection was performed through test on large-scale shaking table [22]. In this study, excellent behavior of connection was observed and yielding in the middle of beam did occur as predicted in monotonic analysis.…”

Assessment of structural damage detection methods for steel structures using full-scale experimental data and nonlinear analysis

“…The white noise test indicates that the equivalent viscous damping ratio is 443 fairy high (i.e., it ranges between 5.3% and 6.6%) regardless of the employed system identification technique. This is 444 due to the friction of the test bed to the sliders (Okazaki et al 2011(Okazaki et al , 2013a). However, this issue diminishes after the 445 14% of the unscaled JR Takatori record because the inertia forces become larger than the corresponding friction forces.…”