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Abstract Reinforced concrete framed residential buildings are remarkably common in Turkey. Observations after recent earthquakes revealed that a great portion of the present building stock has inadequate seismic resistance. Moreover, collapses of several multi-story reinforced concrete buildings under their self-weight have also been observed despite any dynamic activity. The tragic example of the collapse of the "Zumrut" residential building under its self-weight in 2004 and the death of its 93 occupants have highlighted the need to re-examine the structural safety of existing buildings throughout the country. In this study, a multi-story reinforced concrete building located in the same city where the Zumrut disaster occurred, has been investigated. The damage occurred under its self-weight and their causes have been studied in detail. Four columns located in the basement of this nine-story reinforced concrete building have suddenly started to crack and fracture. At this stage, the authors were invited to the building for investigation during which initiation of another column failure was observed. After securing the building, concrete test samples were taken from each floor. The building is then modeled in 3D using a finite element software. A series of analyses have been carried out based on some reasonable assumptions. The demand-to-capacity ratios for each structural member were determined and a vertical incremental nonlinear pushover analysis was performed so that the possible failure mechanisms could be determined. The results indicated that the limited reserve capacity of columns and variation in material properties led to the observed failure. Highligts • A multi-story reinforced concrete building was damaged under the influence of its self-weight. • Four columns in the basement of nine-story reinforced concrete building have suddenly started to crack. • The building is modeled within a finite element software three dimensionally and a vertical incremental nonlinear pushover analysis was performed. • The demand-capacity ratios for each structural member were determined and possible failure mechanisms determined. [ABSTRACT FROM AUTHOR]

This study describes the methodology implemented to establish the ground-motion logic-tree for national probabilistic seismic hazard map of Turkey for shallow active crustal regions. The presented procedure provides quantitative information to guide the hazard experts while establishing the logic tree to capture the epistemic uncertainty in ground-motion characterization. It uses non-data-driven and data-driven testing methods to identify and rank candidate ground-motion prediction equations (GMPEs) under a specific ground-motion database. The candidate GMPEs are subjected to visual inspection and are classified into center, body and range (CBR) spectral estimates for a proper consideration of epistemic uncertainty. The GMPEs classified into CBR are then used in a suite of seismic hazard sensitivity analysis to establish the most suitable GMPE logic-tree whose spectral estimates are not biased by any one of the GMPEs in the logic-tree structure. The sensitivity analysis considers normalized spectral ordinates and is not manipulated by the spectral amplitudes. The proposed procedure is inherited from the relevant studies of the Earthquake Model of the Middle East (EMME; www.efehr.org:8080/jetspeed/portal/emme.psml) regional seismic hazard project. This paper also highlights the similarities and differences in ground-motion characterization between EMME and our approach. [ABSTRACT FROM AUTHOR]

Estimation of seismic losses is a fundamental step in risk mitigation in urban regions. Structural damage patterns depend on the regional seismic properties and the local building vulnerability. In this study, a framework for seismic damage estimation is proposed where the local building fragilities are modeled based on a set of simulated ground motions in the region of interest. For this purpose, first, ground motion records are simulated for a set of scenario events using stochastic finite-fault methodology. Then, existing building stock is classified into specific building types represented with equivalent single-degree-of-freedom models. The response statistics of these models are evaluated through nonlinear time history analysis with the simulated ground motions. Fragility curves for the classified structural types are derived and discussed. The study area is Erzincan (Turkey), which is located on a pull-apart basin underlain by soft sediments in the conjunction of three active faults as right-lateral North Anatolian Fault, left-lateral North East Anatolian Fault, and left-lateral Ovacik Fault. Erzincan city center experienced devastating earthquakes in the past including the December 27, 1939 (Ms = 8.0) and the March 13, 1992 (Mw = 6.6) events. The application of the proposed method is performed to estimate the spatial distribution of the damage after the 1992 event. The estimated results are compared against the corresponding observed damage levels yielding a reasonable match in between. After the validation exercise, a potential scenario event of Mw = 7.0 is simulated in the study region. The corresponding damage distribution indicates a significant risk within the urban area. [ABSTRACT FROM AUTHOR]

Simulated ground motions can be used in structural and earthquake engineering practice as an alternative to or to augment the real ground motion data sets. Common engineering applications of simulated motions are linear and nonlinear time history analyses of building structures, where full acceleration records are necessary. Before using simulated ground motions in such applications, it is important to assess those in terms of their frequency and amplitude content as well as their match with the corresponding real records. In this study, a framework is outlined for assessment of simulated ground motions in terms of their use in structural engineering. Misfit criteria are determined for both ground motion parameters and structural response by comparing the simulated values against the corresponding real values. For this purpose, as a case study, the 12 November 1999 Duzce earthquake is simulated using stochastic finite-fault methodology. Simulated records are employed for time history analyses of frame models of typical residential buildings. Next, the relationships between ground motion misfits and structural response misfits are studied. Results show that the seismological misfits around the fundamental period of selected buildings determine the accuracy of the simulated responses in terms of their agreement with the observed responses. [ABSTRACT FROM AUTHOR]

SUMMARY A large scale seismic risk prioritization study was conducted for medium-rise, gravity-designed reinforced concrete residential buildings in Istanbul. The implemented procedure was based on evaluating selected building parameters that could be easily observed or measured during a systematic sidewalk survey. The survey was actually conducted on approximately 100,000 buildings in the six subprovinces of Istanbul over the period 2004-2009 by a large team of trained surveyors. The collected data were processed to calculate a safety score for each building, which is in turn used for ranking the surveyed buildings with respect to their expected seismic performance under the calculated ground motion intensities produced for a scenario earthquake of M7.5 along the Marmara Sea Fault. The basic objective of this laborious study was to identify the buildings that would be likely to sustain severe damage or suffer collapse during the expected Istanbul earthquake. Accordingly, a rational risk reduction planning can be conducted for minimizing the life and property losses. This paper presents the methodology, results of field surveys and risks evaluated in 100,000 buildings. As a result, 52,000 buildings have been classified as 'high risk', that is, expected to sustain severe damage or collapse during the scenario event. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Safety of a highway infrastructure system depends very much on the proper maintenance of bridges. The level of required maintenance is, typically, determined through a series of regular field inspections with the guidance of safety–economy trade-off. In Turkey, bridge maintenance, repair, and rehabilitation are currently performed on an as-needed basis. Time-dependent reliability analysis cannot be utilized for Turkish bridges for the time being since the majority of the bridges are either not regularly inspected or not inspected at all. The purpose of this paper is to propose a simple method to assess the remaining service life of a bridge by defining a relationship between its current condition rating and its age by evaluating a set of bridges at different ages. In a case study, 28 bridges were inspected for the first time to assess the average life expectancy. The average life of a bridge was predicted to be 80 years, and for this set of bridges, the main body components were found to deteriorate more than earth retaining and serviceability components. [ABSTRACT FROM AUTHOR]

The capacity curves of various structural systems that are used in the HAZUS methodology to determine seismic vulnerability were developed based on the seismic design codes. These capacity curves are, therefore, very idealistic and do not take into account variations in the regional design practice. This article presents the results of nonlinear static analyses of representative reinforced concrete frame buildings located in Turkey to obtain their capacity curves. A representative set of buildings was selected from existing RC buildings. The parameters such as yield over-strength ratio, fundamental period, post elastic stiffness, yield and ultimate drift ratios, and yield base shear coefficient have been obtained from the idealized capacity curves. These parameters are used in HAZUS to determine seismic response of buildings under a given hazard level. This seismic response is then used in predetermined fragility curves to estimate the expected loss for the particular building type. The capacity curves developed herein for Turkish buildings were compared with other studies and HAZUS recommendations. [ABSTRACT FROM AUTHOR]

A detailed seismic performance assessment procedure has been developed for reinforced concrete (RC) frame buildings with masonry infill walls. The procedure is based on member damage functions, in terms of interstory drift ratios. These functions are developed for the primary components, namely, columns, beams, and infill walls. For developing these functions, analytical investigations to determine the influence of several parameters on the damageability of components were combined with experimental data. A new approach has been developed to synthesize component damage states to determine the story and eventually the building level performance states. The procedure has been calibrated and compared with other procedures by predicting the observed performance of three buildings exposed to recent earthquakes in Turkey. It is concluded that the developed procedure can satisfactorily predict the damage experienced by most of the components of the studied buildings. Moreover, the procedure reasonably captured the observed building damage states. Accordingly, the developed procedure can be used for a reliable performance assessment as well as performance-based design of RC frame structures. [ABSTRACT FROM AUTHOR]

A preliminary procedure to assess rapidly the likely seismic performance of existing reinforced concrete buildings is presented. In this procedure, a Capacity Index is computed considering the orientation, size and material properties of the components comprising the lateral load resisting structural system. This index is then modified by several coefficients that reflect the quality of workmanship and materials, and architectural features. The procedure has been tested and calibrated based on the data compiled from damage surveys conducted after the earthquakes that occurred within the last decade in Turkey. The method classifies the buildings either as safe, meaning the building might suffer no severe damage or as unsafe, indicating that life safety performance level would not be met. [Copyright &y& Elsevier]

Simulated ground motion records have recently become major alternatives to real records. In this study, differences between simulated and real record sets are evaluated in terms of alternative ground motion intensity measures. As case studies, two regions in Turkey (Erzincan and Duzce) are considered. A large set of simulated records involving a wide range of magnitudes, source-to-site distances, and site properties is prepared. The fundamental seismological properties of stochastically-simulated records are compared with those of actual motions. A real ground motion dataset for each region with consistent source, distance, and site properties is formed. Alternative intensity parameters are computed for real and simulated sets and evaluated through statistical analyses involving Kolmogorov–Smirnov test. Varying patterns are observed for different levels of intensity parameters. Correlations of intensity measures with maximum inelastic displacements obtained from single-degree-of-freedom models are investigated. Better correlations are observed for simulated data emphasizing significance of region-specific ground motions. • Differences between seismic intensity measures for simulated and real records are investigated. • Alternative intensity parameters are evaluated for both real and simulated record sets. • Varying patterns are observed for different levels of ground motion intensity parameters. • Correlations of intensity measures with seismic response of SDOF models are investigated. • Better correlations are observed for simulated data emphasizing their significance. [ABSTRACT FROM AUTHOR]