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SUMMARYThe authors developed a buckling-restrained brace that enables increased design freedom at both ends of the core plate and strict quality control while providing stable hysteresis characteristics even under high strains. The buckling-restrained brace can be formed by welding a core plate covered with unbonded material to a pair of mortar-filled channel steels (steel mortar planks) as a restraining part. The use of this approach enables visual confirmation of the status of the mortar filling and also facilitates standardizing structural members and member-by-member quality control. Specimens of a buckling-restrained brace with different steel mortar plank heights are fabricated to adjust the restraining force, along with specimens with different core plate width-to-thickness ratios. The tests were conducted to reveal the hysteretic characteristics of the braces, as well as their cumulative plastic strain energy, elastoplastic properties, and stiffening properties. A performance evaluation formula as well as a buckling-restrained brace design method using the test results is proposed.

SUMMARYThis paper presents the results of a pilot test conducted for evaluating the energy dissipation behaviour of shear panels made of low yield steel whose 0-2 per cent offset yield stress is 120 MPa. A total of six full-scale shear panels were tested with the loading condition, stiffener spacing, and magnitude of axial force as test variables. The shear panels tested yielded at a shear force that is approximately 4 of the yield shear force of equivalent shear panels made of common mild steel. Shear panels with proper stiffener arrangement exhibited stable hysteresis, thus ensuring large energy dissipation capacity. Sufficient strain hardening was observed in the shear panels tested, with their energy dissipation capacity about 1.5 times larger than that of an equivalent linear-elastic and perfect-plastic system. Plate buckling did not lead the shear panels to immediate degradation in their energy dissipation capacity. Post-buckling resistance was found to be a subject that requires further studies for quantifying the performance of shear panels made of low yield stress steel as hysteretic dampers.

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This paper first reviews the concept of the damage‐controlled structure (DCS) which is a kind of passive damping technology, proposed before the Hyogoken‐Nanbu Earthquake in Japan and the Northridge Earthquake in the USA. The philosophy, the necessity and the potential of the damage‐controlled structure are stated in the first two sections of this paper. Second, a modified shear‐bending beam model and a rational dynamic analysis method of three‐dimensional frame for the damage‐controlled structure with passive energy dissipation devices are reviewed. Thirdly, a series of dynamic loading test results of modeled damage‐controlled steel frame with hysteretic dampers are presented. Finally, a number of actual example building projects which exemplify the current seismic design trend using the passive damping technology in Japan are reviewed.