SUMMARYSix cyclic tests were conducted on three full-scale subassemblies to investigate the behavior of interior beam-to-column post-tensioned (PT) connections. Strands were placed along each side of the steel beam web, passing through the steel column to provide precompression between the beams and a column. Top and bottom energy-dissipating (ED) bars, passing through the column and welded to the beam, were used to increase the moment capacity and ED capacity of the connection. One of the subassemblies also had a composite concrete slab with discontinuity at the column centerline to eliminate restraint from the metal deck, reinforcement, and welded wire mesh. The objectives of this paper were to investigate the following: the durability of the connection by loading each specimen twice, the ED capacity of the ED bar, and the effects that the type of ED bar and type of composite slab have on the self-centering behavior of the connection. The experimental results showed that: (1) the connection could sustain severe inelastic cyclic loading at least twice without strength degradation, (2) the ED capacity of the bar was much larger than that dissipated by a single AISC loading protocol, and (3) a specimen with a discontinuous composite slab, which opened freely at the centerline of the column, ensured the same self-centering hysteretic behavior as the bare steel specimen. However, the decompression moment of the PT connection decreased significantly at each interstory drift, resulting in an early opening of a gap at the beam-column interface.

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It has been found that any one vibration “mode” of an inelastic multistory two-way asymmetrical building structure can be represented by a three-degree-of-freedom (3DOF) modal system representing two modal translations and one modal rotation. This study introduces the inelastic response spectra constructed from the inelastic 3DOF modal systems, which is specifically useful for multistory two-way asymmetric-plan buildings subjected to bidirectional ground excitations. These spectra for asymmetrical structures (SAS) provide the three-component inelastic peak modal responses of multistory two-way asymmetric-plan buildings subjected to bidirectional ground excitations. In order to construct the SAS, the independent elastic parameters of the 3DOF modal systems were identified and the inelastic 3DOF modal parameters versus the strength ratio relationships were established. The parametric study of the 3DOF modal parameters showed the ranges and the variation trends of these parameters. Two example buildings are analyzed to verify the effectiveness of the above-mentioned investigations.