Research Article Soil-Structure Interaction Effect on Fragility Curve of 3D Models of Concrete Moment-Resisting Buildings Ali Anvarsamarin , 1 Fayaz Rahimzadeh Rofooei , 2 and Masoud Nekooei 1 1 Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Civil Engineering Department, Sharif University of Technology, Tehran, Iran Correspondence should be addressed to Fayaz Rahimzadeh Rofooei; rofooei@sharif.edu Received 21 August 2017; Revised 23 January 2018; Accepted 27 February 2018; Published 19 April 2018 Academic Editor: Sara Muggiasca Copyright © 2018 Ali Anvarsamarin et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Tis paper presents the probabilistic generation of collapse fragility curves for evaluating the performance of 3D, reinforced concrete (RC) moment-resisting building models, considering soil-structure interaction (SSI) by concentration on seismic uncertainties. It considers collapse as the loss of lateral load-resisting capacity of the building structures due to severe ground shaking and consequent large interstory drifs intensifed by -Δ efects as well as the strength and stifness deterioration of their lateral load carrying systems. Te estimation of the collapse performance of structures requires the relation between the intensity measure (IM) and the probability of collapse that is determined using the generated collapse fragility curves. Considering a number of 6-, 12-, and 18-story, 3D, RC moment-resisting buildings, two scalar IMs are employed to estimate their collapse fragility curve. On the other hand, the efect of the site soil type on the collapse fragility curves was taken into account by considering the soil-structure interaction. According to the obtained results, adopting the average of spectral acceleration (Saavg) intensity measure is more efcient in capturing the efect of the inherent uncertainties of the strong ground motions on the structural response parameters. In addition, considering the SSI for soil type D with shear-wave velocity of 180 m/s to 360 m/s reduces the median of intensity measure (IM = Sa( 1 )) of fragility curve in 6-, 12-, and 18-story buildings by 4.92%, 22.26%, and 23.03%, respectively. 1. Introduction According to a conventional defnition, the collapse of build- ings during or within short time afer earthquake excitation is due to the loss of their structural system integrity that in turn is caused by generation of large deformation or force demands in their primary structural components. Te stochastic nature of the strong ground motions as well as the fact that no numerical approach can exactly model all the features of complex structural behavior makes the seismic collapse analysis of structures very difcult. Probabilistic techniques on the other hand have introduced the combi- nation of variable possible sources in collapse assessment process as well as collapse potential of available buildings in the form of collapse probability [1–4]. Te probabilistic estimation of maximum story drif demands by considering a 9-story, moment-resisting frame building subjected to severe ground motions was improved by Stoica et al. [5]. Tey concluded that the three-parameter log-normal distribution describes maximum story drifs at higher values of spectral acceleration more rationally; statistically adding values to replace truncated data points provides better ftness in maxi- mum drif demand prediction when the structure is close to the onset of dynamic instability, and the least-squares ftting of the log-normal distribution yields parameters that provide an improved ft compared to that from maximum likelihood estimation and the method of moments. Current seismic design codes do not take into account duration efects and are mainly based on spectral acceleration. Tis fact is because of the lack of actual recorded for long duration ground motion and debates about whether artifcial records can take place of recorded motions. In the last few years, many long duration ground motions have been recorded afer events such as Tohoku. Tis led to few researches on the efect of considering ground motion duration on buildings damage and risk of collapse (e.g., [6]). Hindawi Shock and Vibration Volume 2018, Article ID 7270137, 13 pages https://doi.org/10.1155/2018/7270137