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To investigate the seismic behavior of partially-restrained steel frame with RC infill walls, an innovative subassemblage was proposed to consider the influence of boundary condition on the infill walls reasonably. Three 1/3 scale, one-bay and three-story test specimens were carried out under low cycle reversed test, and the effect of infill walls type on structural performance was studied. The hysteretic curves, skeleton curves, ductility, stiffness degradation, energy dissipation, and the distribution of lateral shear were obtained. Test results reveal that test specimens with slit RC walls and concealed vertical slit RC walls take on the significant full hysteretic curves, and high deformability and energy dissipation, but small lateral strength and stiffness. Both test specimens produce flexural failure mode of slit wall. Test specimen with solid infill walls has narrow hysteretic curve, low deformability and energy dissipation, but high lateral strength and stiffness, which takes on the shear failure mode of infill walls. The employment of infill walls decreases the rotation requirement of connection resulting from earthquake. During the test, the maximum connection rotation angles of three specimens are no more than 0. 025 rad, which can avoid the brittle failure of surrounding steel frame due to connection failure. The infill walls sustain approximately 80% lateral strength at initial loading stage, and with the lateral strength increase this ratio gradually decreases. [ABSTRACT FROM AUTHOR]

The damage of buildings under near-fault earthquakes was related to the instantaneous input energy. In order to reflect near-fault pulse effect, a total of 10 near-fault ground motion records of stiff soil site condition were selected to construct the maximum effect cyclic energy (MECE) spectrum appropriate for seismic design. The base shear of steel plate shear wall (SPSW) was determined based on the MECE spectrum. Velocity pulse effect and hysteretic behavior of different structural system were taken into account in this energy-based seismic design method of SPSW. The design formula of steel beam and column surrounding of SPSW were proposed based on previous research results. A ten-story, three-span SPSW was designed based on this new design method, and seismic behavior was evaluated by nonlinear time history method. The analytical results show that the maximum average drift of SPSW can satisfy the deformation requirement of Chinese seismic code under frequent and rare earthquake levels, and the SPSW structure exhibits the ideal progressively developed plastic mechanism. The reliability and accuracy of this new design method are verified. [ABSTRACT FROM AUTHOR]

In order to study the hysteretic behavior of partially encased composite (PEC) columns fabricated with thinwalled built-up section, three full-scale specimens were designed based on previous research results in the field of PEC column, which represented the middle-story column in the frame structure. The tests of the specimens were conducted under constant axial compression and lateral cyclic loading about the column weak axis. The local buckling of the flange of the thin-walled built-up section, the crack development and crushing of concrete were investigated. The hysteretie loops were obtained. Based on the test results, the specimens' performance were analyzed, including the load-carrying capacity, lateral stiffness, seismic ductility, energy-dissipation capacity and failure mode. The research shows that the specimens exhibit good deformation and energy-dissipation capacities; the failure is primarily induced by the crushing and spalling of concrete and the yield of transverse links with the local buckling in flange of thin-walled built-up section at the comer region of column. The study provides experimental basis for revising the specification and engineering practice of the structure comprised of PEC columns. [ABSTRACT FROM AUTHOR]

In order to research the seismic performance of RC frames filled with Y-steel brace, three one-bay two-story specimens of one half scale were tested under low cycle reversed loading. Failure mechanism, hysteretic behavior, ductility, rigidity degeneration and energy-dissipation of specimen were analyzed. Experimental studies and analysis show that the use of Y-steel brace for reinforcement of RC frame is rational and feasible, and most of the lateral load of structure resisted by Y-steel brace and the beam-column nodes of RC frames is rarely damaged. The joint of link and concrete beam is not damage and the panel joint details are reasonable. The failure of Y-steel brace causes the structure failure. Hysteretic curves of load-lateral drift ratio of specimen have a certain degree of pinching at initial loading stage and hysteretic curves of specimens become relative plump after link yields. The hysteretic curves of load-story lateral drift ratio of the second floor are plumper than the first floor and the lateral deformation of the second floor is larger than the first floor. The existence of the floor increases the stiffness of the frame beams, reducing the cracks of the beam. The constructional details of nodes has little effect on lateral stiffness and has great influence on the deformation capacity of structure. The stiffness degradation degree should be considered when retrofitting earthquake damaged RC frame structures. Design method of Y-steel brace is presented based on the test. [ABSTRACT FROM AUTHOR]