INFLUENCES OF THE SHAPE OF HOLES ON THE HYSTERETIC PERFORMANCE OF ASSEMBLED ENERGY DISSIPATION BRACES

A novel type of brace composited of H-shaped steel with holes on the webs, force transmission channels and assembling bolts was proposed for structural energy-consumption and buckling restraint. The effects of the web holes on the energy dissipating ability of the brace were studied by cyclic axial loading tests and the finite element method. The test results indicate that this type of brace has a remarkable hysteretic behavior. The energy dissipation and failure mode of brace specimens were governed by the plasticity development of the plates between the web holes, in which the plastic zones were concentrated at the ends of the plates between slotted or elliptical holes and in the middle of the plates between diamond holes. All bolts and channels remained elastic throughout the tests. The finite element analysis reveals that the width of the web greatly affects the initial stiffness and strength of the braces with slotted holes, while it only slightly affects the behavior of the braces with elliptical holes. The hole distances had a minor effect on the behavior of the braces with diamond holes. The effects of the web thickness on the initial stiffness and strength of the braces with slotted, elliptical, and diamond holes were similar. Design suggestions were proposed according to the analysis results that the premature buckling can be avoided by increasing the height-to-width ratio, by reducing the web thickness of H-shaped braces, or by enlarging the flanges of the channel, and that the bolt spacing shall be less than 4.5 times the diameter of the bolt holes.