Influence of a Soft Story on the Seismic Response of Non-Structural Components

Abstract

Multi-story, reinforced-concrete (RC) building structures with soft stories are highly vulnerable to damage due to earthquake loads. The soft story causes a significant stiffness irregularity, which has led to numerous buildings collapsing in previous seismic events. In addition to the structural collapse, the failure of non-structural components (NSCs) has also been observed during past earthquakes. In light of this, this study investigates the effect of a soft story and its location on the seismic behavior of a supporting building and NSCs. The soft story is assumed to be located on the bottom (ground), middle, and top-story levels of the considered building models. Story displacements and inter-story drift ratios are evaluated to assess structural behavior. The floor response spectra and the amplification effects of NSC on the floor acceleration responses are studied to understand the behavior of NSCs. The analysis results revealed that the bottom soft story exhibits a considerable vertical stiffness irregularity, and its position substantially affects the floor response spectra. The amplification in the floor acceleration response was found to be greater at the soft-story level. This study reported that middle soft-story buildings exhibit the most remarkable amplification in the component’s acceleration. Finally, peak floor response demands are compared with the code-based formulation, and it is found that the code-based formulation’s linear assumption may lead peak floor response demands to be underestimated or overestimated.

Investigation on floor response spectra of a three-story building exposed to near- and far-field earthquakes

“…4, it can be observed that the two peaks observed in the elastic and inelastic FRS are recorded close to the structure's elastic and inelastic modal periods (Table 3), respectively. This finding from this study is consistent with the outcomes of the previous research [11][12][13]. The Floor Response Spectra (FRS) exhibit a consistent trend of increasing magnitude from the first floor at the bottom to the third floor at the top.…”

“…The floor response spectrum (FRS) method is an analytical approach that operates by separating various considerations [7][8][9][10][11][12][13]. Initially, the primary structure undergoes dynamic analysis independently, without factoring in the secondary system's influence.…”

Vulnerability of Non-Structural Elements (NSEs) in Buildings and Their Life Cycle Assessment: A Review

“…For seismic resilient buildings, the performance of NSEs is important for absorbing earthquake damages [56]. NSEs with a short period attract more earthquake forces when present on the lower floors of the building without any soft story effect [56] The recovery path for a structure in terms of function vs. time as studied in the research by Henry V. Burton et al, 2018 [57], is displayed below in Figure 13. The 2475-year hazard scenario shows no difference between the no utility dependence and the baseline utility dependence [58].…”

“…Heidari et al, 2020 [54] showed that governments should formulate useful policies to reduce vulnerability and increase resilience. The research of Pesaralanka et al, 2023 [56] is limited to linear analysis only; the damages of NSEs and EAL need to be researched further. Asadi et al, 2019 [28] showed that diagrids have good lateral capacity and can reduce CO 2 emissions, but sufficient knowledge of the construction quality is required.…”

Vulnerability Analysis of Non-structural Elements (Nse) in Buildings and Their Life-Cycle Assessment: A Review

“…For seismic resilient buildings, the performance of NSEs is important for absorbing the earthquake damages [61]. NSE with short period attract more earthquake forces when present in the lower floors of the building without any soft story effect [61] The recovery path for a structure in terms of function vs time can be displayed below in Figure 25: The 2475-year hazard scenario shows no difference between the no utility dependence and the baseline utility dependence [63]. For a retrofit cost of $ 100 (Millions) on a community, the fatalities, CO2 emissions etc.…”