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Abstract: Advancing the seismic resilience of building systems is an active area of research in earthquake engineering. Ensuring safe egress in and out of buildings during extreme events, such as an earthquake, is essential to supporting this effort. To this end, understanding the seismic response of stairs facilitates the robust design of egress systems to ensure they can remain operable after an earthquake. From prior earthquake events and physical experiments, it is understood that stairs with a flight to landing fixed connection at multiple levels within a building are prone to damage. In addition, the stair system with flight to landing fixed attachments may affect the dynamic behavior of the building. To accommodate seismic inter‐story drifts, a kinematically free connection between the stairs and landing has been proposed. Herein this connection is referred to as a drift‐compatible stair connection. To investigate and aid in the design of such a connection, a unique set of shake table experiments were conducted at the University of Nevada, Reno. In this paper, an overview of these tests is presented, and a high‐fidelity finite element model of the tested stair system is used to predict the responses measured during these experiments. Developed in Abaqus, the robustness of the modeled stair unit is investigated considering a variety of contrasting connections, namely, drift‐compatible connections, fixed ends and one end fixed and the other free. Results from these numerical simulations offer guidance towards development of simplified models of multi‐level stair subsystems. Such models are needed when investigating seismic resilience of building systems across a wider range of hazard levels. Furthermore, best practices observed utilizing the models developed and evaluated herein against experimental data will be useful for subsequent analysis of larger stair tower models, such as the 10‐story stair system implemented in the NHERI Tall Wood mass timber building with post‐tensioned rocking walls, conducted in 2023 at the UC San Diego Large High‐Performance Outdoor Shake Table.

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]