An approximate procedure for estimating the member demands in mid-rise reinforced concrete buildings
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An approximate procedure for estimating the member demands in mid‑rise reinforced concrete buildings Ugur Akpinar1 · Baris Binici1 · Ahmet Yakut1 · Kagan Tuncay1 Received: 17 March 2020 / Accepted: 8 September 2020 © Springer Nature B.V. 2020
Abstract Seismic assessment of mid-rise reinforced concrete buildings is important for urban seismic risk reduction. Nonlinear time history analysis is the state-of-the-art analysis tool for this purpose. However, the number of such buildings may reach to several tens of thousands in metropolitan cities of earthquake prone countries. This necessitates faster yet sufficiently accurate assessment methods to mitigate the seismic risk. In this study, a simple and efficient approach is developed and validated for the assessment of such buildings. The proposed method relies on estimating the reduced secant stiffness values for structural members based on elastic analysis. Afterwards, subsequent elastic analyses with the reduced stiffness values is conducted employing the equal displacement rule. The procedure is tested for twelve buildings with and without shear walls, and torsional irregularity. The member end chord rotation results obtained with the proposed procedure are compared with the mean results of eleven nonlinear time history analyses. It is found that the proposed procedure can estimate column and beam chord rotation demands with reasonable accuracy, significantly reducing the computational time. Keywords Mid-rise buildings · Approximate linear analysis · Chord rotation · Seismic assessment
1 Introduction Many cities in seismically prone countries have a large mid-rise building stock designed and constructed in 1960s–1980s i.e. prior to the state-of-the-art seismic codes. Seismic assessment and strengthening of these buildings are important for seismic risk reduction * Ahmet Yakut [email protected] Ugur Akpinar [email protected] Baris Binici [email protected] Kagan Tuncay [email protected] 1
Department of Civil Engineering, Middle East Technical University, 06800 Ankara, Turkey
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Vol.:(0123456789)
Bulletin of Earthquake Engineering
in urban regions. For low-rise buildings with single mode dominant response, linear or nonlinear static analysis procedures are employed (ATC 1996; ASCE 2000, 2017; DEMP 2018; CEN 2005). On the other hand, nonlinear time history analysis appears to be the most reliable approach for mid to high-rise buildings or buildings with irregularities. Nonlinear time history analysis brings a number of challenges such as ground motion selection, sensitivity to modeling assumptions, difficulties in estimating local demand parameters and significant pre- and post-processing time and effort. Hence, more practical procedures to estimate seismic demands are still needed. Turkey lies in a highly seismic active zone and there is an urgent need of seismic assessment of existing buildings. In this regard the so-called Urban Renewal Law that came into action in 2012, gives the responsibility to households, local municipalities and ministry aut
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