A discontinuous cantilever beam analogy for quantifying higher mode demands in stacked rocking cores

Abstract

Summary Stacked rocking core (SRC) combinations are innovative sustainable structural assemblies that mitigate seismic demands through uplift at the hinge joints and direct damage to replaceable fuses. The stacked segments curtail substantially higher mode effects by the relative motions between multilevel cores. Currently, few research studies have quantified the behavior of SRCs under earthquake shaking. This paper presents a novel closed‐form solution for quantifying the higher mode demands of stacked braced frames subjected to seismic excitation. The mathematical formulae for modal analysis are derived using the analogy of discontinuous cantilever beam and Euler–Bernoulli equation. The proposed equations provide a method for rapid analysis and preliminary design of low‐ to mid‐rise SRCs. A parametric study is carried out to investigate the influences of rotational restraint of segments and the location of the rocking joints. Results verified by time response analysis indicate the validity and accuracy of the suggested formulae.

Functional recovery evaluation of hybrid self‐centering piston‐based braced frames

“…22 This paper is dedicated to evaluating the functional recovery of a specific type of seismic-resilient archetype designed to minimize structural damage during earthquakes by preventing plastic deformation and permanent displacements. Examples of such systems encompass self-centering braced frames, [26][27][28][29] controlled rocking-core systems, [30][31][32][33][34] multiple rocking joints, 35,36 and isolated rocking cores. 37,38 While these innovative structural systems are designed to withstand seismic forces with minimal damage, they encounter challenges related to functional recovery.…”

Structural optimization of vertical isolated rocking core-moment frames

“…A rocking core-moment frame (RCMF) archetype is one of these novel structural assemblies. The RCMFs combinations can be equipped with pin-supported cores (Wada et al, 2011; Grigorian and Grigorian, 2015), stepping braced frames (Eatherton et al, 2014; Steele and Wiebe, 2020), stacked rocking frames (Wiebe and Christopoulos, 2009; Rahgozar et al, 2021a, 2021b), and self-centering bracing systems (Issa and Alam, 2019a, 2019b). The rocking cores (RCs) impose uniform deformation to moment frames (MFs) (Rahgozar et al, 2016a, 2018a, 2018b) and act like a single-degree-of-freedom system (Martin et al, 2019; Rahgozar et al, 2016b; Rahgozar and Rahgozar, 2020, 2021; Steele and Wiebe, 2016).…”

“…Accordingly, the proper design parameters need to be adjusted for minimizing the MF displacement. Although a few research have been conducted for reliability and optimization analyses of self-centering systems (Hashemi et al, 2021; Hormozabad and Soto, 2021; Rahgozar et al, 2021a, 2021b), there is a lack of practical design and optimization research for VI-RCMFs. It is worth noting that the design parameters of VI-RCMFs cannot readily be optimized by analytical formula due to their complex and nonlinear responses.…”