LARGE-SCALE SEISMIC TESTING OF KNEE-BRACE-FRAME

In a knee-brace-frame (KBF), one end of the brace is connected to a sh ort knee element instead of beam-column joint. The brace provides the required lateral stiffness, whereas the ductility is obtained through shear yielding of the knee element. Large-scale dynamic testing of a K BF with shear yielding knee is described in this paper. When a two-sto ry KBF with rolled I-sections as knee members was subjected to base ex citation through pseudo-dynamic testing, inducing a shear strain of 0. 1, it was found that the KBF could dissipate a large amount of energy without any pinching in the hysteretic loops or significant deteriorat ion in strength and stiffness provided that the knees are designed to inhibit: local and lateral-torsional buckling. The test results reveal that the variation of shear stress with the shear strain in the knee could be approximated by a bilinear hysteretic curve with a strain har dening slope of 0.02-0.04. The out-of-plane displacements at the knee- brace joints and vertical displacements at the knee-beam joints are fo und to be small.