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Hurricane and tsunami events can generate extreme water flows in nearshore regions of the United States with catastrophic consequences to coastal structures. Field records have shown that light-frame wood structures exhibit high vulnerability to wave-induced forces due to their light construction characteristics, which feature flexible connections and slender pile foundation systems. Previous research has studied the behavior of these structures under wave action, but most studies used rigid body modeling, which is shown in this study to be insufficient for capturing the force demand on these structures. Using a fluid-structure interaction (FSI) framework, this research investigated the structural and soil flexibility effects in the interaction between elevated light-frame wood structures and water flows. Study variables included the flexibility of timber-to-timber connections, soil type, pile embedment, wavelength, and wave amplitude. The study concluded that structural and soil responses to water flows can introduce strong coupled motions. Neglecting this coupling effect may underestimate the force demand on the light-frame wood structures by more than 40%. Accounting for both structural and soil flexibilities is necessary to accurately quantify the wave force demand of these structures. [ABSTRACT FROM AUTHOR]

• This research study enhances a novel Fluid-Structure Interaction (FSI) framework, named as ALE-SSM, to account for geometric and material nonlinearities in structural responses to fluid-induced loading. • ALE-SSM is a unique approach on how to preserve the physical structural geometry in the coupling of force-based elements with fluid domains, which is necessary to perform meaningful FSI calculations and account for the spatially distributed fluid forces. • Comparisons with geometrically nonlinear benchmark FSI problems demonstrate the accuracy of the ALE-SSM framework. • Using ALE-SSM, a new benchmark study is developed to study the effects of geometric and material nonlinearities in FSI simulations with force-based elements. A novel methodology was introduced for integrating skeleton-based structural models (SSMs) with an Arbitrary Lagrangian-Eulerian (ALE) formulation to perform fluid–structure interaction (FSI) simulations (i.e., ALE-SSM). In ALE-SSM, the structural domain consists of force-based line elements, which are favored in modeling solid structures because of their computational efficiency. This paper enhances ALE-SSM to account for geometrically nonlinear and inelastic material responses of the structural domain. Geometric nonlinearity is introduced in two stages: (1) at the basic coordinate system of the force-based elements, where second-order effects stemming from the transverse element deformations are accounted for in the element flexibility matrix; and (2) at the global coordinate system, where a corotational formulation is used to perform the geometric transformation from the basic to the global coordinate system. The proposed approach for modeling geometric nonlinearity in ALE-SSM is evaluated with benchmark problems involving large deformations of beam structures positioned parallel and perpendicular to one-phase flows. Next, ALE-SSM is employed to define a new benchmark study that evaluates the effects of geometric and material nonlinearities in FSI simulations with force-based elements. [ABSTRACT FROM AUTHOR]

• Hybrid rocking wall (HRW) systems have been shown to behave satisfactorily under lateral seismic loads. • However, inspection and replacement of the energy dissipating bars used in HRWs may not be economically achieved after earthquake events. • This paper presents a new design concept for HRWs utilizing a localized heat treatment methodology to concentrate hysteretic action in replaceable segments of the bars. • The proposed HRW system was examined analytically in this paper and detailing recommendations for the energy dissipating bars were developed. Rocking walls continue to gain interest in seismic regions due to their ability of re-centering the building system after major earthquakes. However, they have low inherent damping, thus they are often supplemented with energy dissipating elements. A rocking wall supplemented with partially debonded longitudinal bars is named as a hybrid rocking wall (HRW). While HRWs combine re-centering with adequate energy dissipation, inspection and replacement of the energy dissipating bars may not be economically achieved after a major earthquake. This paper proposes an improvement to HRWs with the use of partially debonded longitudinal bars that are locally heat-treated to strategically concentrate hysteretic action in replaceable bar segments. The effect of the heat treatment protocol on the stress-strain properties and microstructure of reinforcing bars is investigated experimentally and a procedure for locally heat-treating standard reinforcing bars is established. Combining the experimental data of heat treatment with an analytical model for HRWs, the reversed-cyclic behavior of the proposed HRW is investigated to characterize the energy dissipation through the heat-treated bar segments, the re-centering capability of the HRW, and other key design parameters of the proposed wall system. [ABSTRACT FROM AUTHOR]