Search

Bidirectional quasi-static cyclic loading was applied to a subassembly of drywall partition walls integrated with cross-laminated timber rocking walls. Details aimed to reduce seismic damage to the partition walls were investigated, such as slip connections of partition walls to the diaphragm and gap detailing for the wall intersections. Telescoping detailing eliminated damage to the framing at the wall ends compared to traditional slip-track detailing. The distributed gap wall delayed the damage to about 1% inter-story drift. In the corner gap wall, the sacrificial corner bead opened up at low drifts (0.43%), but the wall was damage-free until more than a 2% drift. [ABSTRACT FROM AUTHOR]

Prior studies, which have been limited to horizontal ground shaking, have generally concluded that soil–structure interaction (SSI) has a negligible influence on the seismic response of isolated buildings. In this study, the effect of SSI on the response of a computational model of an isolated building using triple friction pendulum bearings is investigated. The analysis shows that SSI can amplify story drifts and accelerations when the model is subjected to 3-D shaking including a vertical component. Amplification occurs due to a vertical-horizontal coupling effect that is explained using the modal properties of the numerical model. Based on a parametric study using the key parameters of foundation system, it is concluded that amplification occurs when the effective shear wave velocity of the soil falls into a specific range. In this case, the response of the computational model is very sensitive to the hysteretic damping ratio of the soil, Poisson's ratio of the soil and the footing size. [ABSTRACT FROM AUTHOR]

Seismic base isolation systems are mainly used to reduce seismic demands and minimize earthquake effect on structure performance. In this study, the fundamental dynamic response of structures with three-dimensional (3D) isolation systems is explored using a simplified rigid block model. A parametric study is carried out to evaluate the effect of different site conditions, structure properties and 3D isolation parameters on structure and bearing response. The results show that the acceptable range of 3D isolation periods is 0.5–1.0 s for vertical direction with horizontal isolation period around 3–4 times the vertical period and 20% damping in both directions. [ABSTRACT FROM AUTHOR]

This paper evaluates factors that may influence slab vibration and/or induce a horizontal–vertical (H-V) coupled response of buildings with mass irregularities. Responses are investigated through computational simulation of a hypothetical three-story building with base isolation and conventionally configured. Induced mass eccentricities are observed to influence, in an unpredictable way, the vertical slab acceleration and the H-V coupled response, which is identified through modal analysis and floor spectral analysis. The implications of vertical slab vibrations and H-V coupling behavior on the design forces for nonstructural components and systems (NCSs) are evaluated, and modifications are proposed for consideration. [ABSTRACT FROM AUTHOR]

Seismic resilience and continued operation of bridges after earthquakes are important seismic design criteria. A new seismic protection concept for integral bridge piers is explored that uses sliding bearings to separate the superstructure from the piers. The influence of sliding bearings on the seismic response of a representative 3-span integral highway bridge is investigated. With sliding bearings, the pier column shear force was limited to the bearing design friction force. Furthermore, the abutment ductility demands were found to be insensitive to the friction forces in the sliding bearings because the bridge displacement demands were controlled by the equal displacement rule. [ABSTRACT FROM PUBLISHER]

Seismic isolation systems that mitigate seismic response are generally applied at the base of a building; however, architectural, functional, and cost considerations have motivated the application of isolation systems at inter-story locations. In this article, we systematically examine the effectiveness of inter-story isolation systems as a function of their location, and explore alternative approaches for selecting their properties. Single-story isolation systems are shown to be effective in mitigating force demands above the isolation system but less effective in mitigating forces below the isolation system. Finally, the practical aspects of designing an inter-story isolation system to accommodate light loads are discussed. [ABSTRACT FROM AUTHOR]

Current design codes generally use an equivalent linear approach for preliminary design of a seismic isolation system. The equivalent linear approach is based on effective parameters, rather than physical parameters of the system, and may not accurately account for the nonlinearity of the isolation system. This article evaluates an alternative normalized strength characterization against the equivalent linear characterization. Considerations for evaluation include: (1) ability to effectively account for variations in ground motion intensity; (2) ability to effectively describe the energy dissipation capacity of the isolation system; and (3) conducive to developing design equations that can be implemented within a code framework. [ABSTRACT FROM AUTHOR]

The ASCE 7 equivalent lateral force method for base-isolated buildings applies a triangular distribution of forces to the superstructure. This distribution attempts to approximately account for the observed effects of isolation system nonlinearity on the superstructure response, but a more rational approximation is needed. Using nonlinear regression analysis of median response data from nonlinear response history analysis of representative systems, improved equations are developed to estimate the lateral force distribution in the superstructure. The ASCE 7 distribution, a revision considered by a SEAONC committee, and the improved distribution developed here are evaluated. Only the improved equations are accurate over many system parameters. [ABSTRACT FROM AUTHOR]