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Tall buildings featuring transfer structures are commonly constructed in lower seismicity regions. Discontinuities in load paths of structural systems in the building were found to compromise ductility of the building. In a force-based seismic design procedure, response modification (R) factor is uncertain to cater for the undesirable features. This article presents a methodical approach for evaluating the seismic performance of such buildings. Results of incremental dynamic analyses of case study buildings indicated a high R-factor, due to the inherent over-strength. A local amplification factor ( β D T ) is recommended to account for localised shear at structural walls above the transfer floor level. [ABSTRACT FROM AUTHOR]

Automated Multi-Depth Shuttle Warehouses (AMSWs) are compact storage systems that provide a large surface occupation and therefore maximum storage density. AMSWs represent the future of storage technology, providing substantial savings in terms of cost, space, and energy with respect to traditional warehouses. Currently, designers refer to the standard building codes for the seismic design of AMSWs. Since structural characteristics of AMSWs are considerably different from the steel structures of typical buildings, this current approach used by designers is questionable in terms of safety and efficiency. In this article, the behavior of 5 AMSW structures has been studied performing 150 time-history analyses by direct integration including P-Delta effects. Demand/capacity ratios calculated for each element showed the dominance of the brittle failure mechanism in AMSWs subjected to low-to-moderate seismic actions. These mechanisms mainly took place in upright columns and their base connections prior to the activation of ductile energy dissipation mechanisms of the structure. Based on the results, further improvements have been recommended for the future design provisions, which may lead to a safer seismic design of AMSWs. [ABSTRACT FROM AUTHOR]

Assessing seismic risk in low-to-moderate seismic activity areas like French mainland is a challenge. In these areas, the estimation of large earthquake hazard calls for models driven by sparse observation data and interpretative seismic knowledge. This leads models used in probabilistic seismic hazard assessment (PSHA) and declustering algorithms to large epistemic uncertainties that are overrepresented due to the large amount of parameters used in it. To concentrate epistemic uncertainties into one single method, we intend to limit the number of parameters under consideration by using the non-parametric inter-event time method. This method is empirical and needs a lot of data to be accurate. In the context of sparse large earthquake data, this paper proposes an implementation of the inter-event time method that ensures the stability of main shock proportions for sparse seismic data. We call this implementation magnitude of inferred main shock proportion (MIMP). This method is applied to the historical French seismic catalogue. We use a Monte Carlo Markov Chain to sample the whole space of magnitude uncertainties contained in this catalogue. We produce a set of equiprobable main shock proportion–magnitude and frequency–magnitude distributions. Results are discussed in the light of reference works published in the literature. [ABSTRACT FROM AUTHOR]

Steel concentrically braced frame (CBF) configuration is a common construction application in Europe. In the low-to-moderate seismicity context, European building codes provide two alternative design methods for CBFs; engineers have to choose between a “non-dissipative” method (DCL) neglecting all seismic provisions, and a “dissipative” one (DCM), applying its complex and expensive ductility requirements. Currently, the preferred method is the former one, because of its simplicity. Such a choice may lead on one side to oversized profiles that are unduly expensive, on the other side to possibly unsafe solutions due to the unpredictable nature of the regions characterized by low-to-moderate seismicity, where rare but strong earthquakes are foreseeable. On the other hand, enforcing engineers to apply strict “high-dissipative” rules seems too conservative for this case, which would result in over-safe, but uneconomic structures. This article proposes an adjusted design approach for the low-to-moderate seismicity design of CBF structures, aiming to satisfy both economy and safety criteria. The proposed approach is based on the exploitation of the three features of CBF systems, which have not been deeply investigated so far: “frame action provided by gusset plates”, “contribution of compression diagonal and its post-buckling strength and stiffness”, and “energy dissipation capacity of non-ductile bracing joint connections”. The paper investigates these aspects by means of incremental dynamic analysis of case studies, based on the numerical models calibrated on full-scale experimental tests published elsewhere by the authors. As a result, it provides design recommendations and presents economic comparisons between the buildings designed with current Eurocode approach and the proposed one. [ABSTRACT FROM AUTHOR]

In low-to-moderate seismicity regions, the limited seismic displacement demands could probably render tall buildings remaining nearly elastic during a maximum considered earthquake. Previous studies have shown the capability of the uniform Timoshenko beam model in resembling the dynamic behaviors of regular buildings. This article describes response spectrum analyses on the non-uniform Timoshenko beam model, considering the first four vibration modes to assess the seismic demands on various building types, which encompass low-rise wall or frame buildings and high-rise shear wall buildings with or without transfer structures. Simplified design charts correlating the global seismic demands – spectral accelerations, maximum interstory drift ratios, roof drift ratios and required shear areas – to the fundamental translational period of each building are developed. The structural periods could be determined from in-situ dynamic tests, full frame models or an appropriate period-height equation, the latter of which is provided here by calibrating from in-situ vibration tests of regional buildings constructed in compliance with British Standards. This simplified approach provides a fast track to seismic performance for both existing and new buildings, which could easily be comprehended by engineers without prior knowledge of seismic design. [ABSTRACT FROM AUTHOR]