Person: DENİZ, Derya
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Derya
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DENİZ
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ArticlePublication Metadata only Energy-based sidesway collapse fragilities for ductile structural frames under earthquake loadings(Elsevier, 2018-11) Deniz, Derya; Song, J.; Hajjar, J. F.; Civil Engineering; DENİZ, DeryaIn assessing the likelihood of structural collapse under strong earthquake motions, uncertainties in structural properties and ground motions can be incorporated by use of a probabilistic analysis framework in conjunction with analysis methods such as incremental dynamic analysis (IDA). Maximum inter-story drift ratio (IDR) is typically selected as the key descriptor to characterize the global behavior of structural system in such a probabilistic assessment. The structural collapse capacity is often defined in terms of a threshold value of IDR or a reduced slope of the IDA curve between a selected seismic intensity measure and the corresponding IDR. However, collapse assessment approaches based on IDR may not accurately represent the overall structural collapse behavior due to redistribution and variation of local damage within the structure. Moreover, results of collapse predictions are found to be sensitive to variability in such drift measures, and assumed threshold values used in the collapse criterion. Recently, an energy-based seismic collapse criterion has been developed to describe collapse in terms of dynamic instability of the whole structural system caused by gravity loads. Using the energy-based collapse criterion, this paper proposes a more effective sidesway collapse risk assessment approach of ductile planar frames subjected to horizontal seismic loadings based on a new key descriptor of structural performance. The key descriptor, designated as the equivalent-velocity ratio, is related to the ratio of the energy dissipated through structural degradation to the seismic input energy. Using the equivalent-velocity ratio, a probabilistic collapse assessment method is developed for systematic treatment of uncertainties in the ground motions.ArticlePublication Metadata only Development of composite cold-formed steel-rubberised concrete semi-rigid moment-resisting connections(Elsevier, 2022-06) Bagheri Sabbagh, A.; Jafarifar, N.; Deniz, Derya; Torabian, S.; Civil Engineering; DENİZ, DeryaThis paper presents the development of a composite cold-formed steel (CFS)-rubberised concrete (RuC) semi-rigid moment-resisting connection suitable for framed building structures. The connection comprises built-up tubular cold-formed steel beam and column sections connected using side-plate screwed fasteners and infilled with rubberised concrete. A detailed finite element analysis validated against physical tests is employed to model both bare steel and composite beam-to-column connections subjected to lateral and gravity loadings. The governing design limit states are characterized as local buckling in bare steel beams, connection screw shear failure, and side plate plasticity. It is shown that the strength and ductility capacity of composite connections could be increased by up to 1.44 and 3.46 times, respectively, compared with those of the bare steel connections. The connection rigidity of both bare steel and composite connections can be classified as a semi-rigid joint.ArticlePublication Restricted Community resilience-focused technical investigation of the 2016 Lumberton, North Carolina, flood: An interdisciplinary approach(American Society of Civil Engineers, 2020-08-01) van de Lindt, J. W.; Peacock, W. G.; Mitrani-Reiser, J.; Rosenheim, N.; Deniz, Derya; Dillard, M.; Tomiczek, T.; Koliou, M.; Graettinger, A.; Crawford, P. S.; Harrison, K.; Barbosa, A.; Tobin, J.; Helgeson, J.; Peek, L.; Memari, M.; Sutley, E. J.; Hamideh, S.; Gu, D.; Cauffman, S.; Fung, J.; Civil Engineering; DENİZ, DeryaIn early October 2016, Hurricane Matthew crossed North Carolina as a Category 1 storm, with some areas receiving 0.38-0.46 m (15-18 in.) of rainfall on already saturated soil. The NIST-funded Center for Risk-Based Community Resilience Planning teamed with researchers from NIST's Engineering Laboratory (Disaster and Failure Studies Program, Community Resilience Group, and the Applied Economics Office) to conduct a field study focused on the impacts of the Lumber River flooding in Lumberton, North Carolina. Lumberton is a racially and ethnically diverse community with higher than average poverty and unemployment rates, a typical civil infrastructure for a city of 22,000 residents, and a city council form of government. The field data described in this paper are from the first wave in an ongoing longitudinal research project documenting the impacts and subsequent recovery processes following the 2016 riverine flooding in Lumberton. The initial data collection for this longitudinal community resilience-focused field study had two major objectives: (1) document initial conditions after the flood for the longitudinal study of Lumberton's recovery, with a focus on improving flood-damage and population-dislocation models; and (2) develop a multidisciplinary protocol providing a quantitative linkage between engineering-based flood damage assessments and social science-based household interviews that capture socioeconomic conditions (e.g., social vulnerabilities related to race, ethnicity, income, tenancy status, and education levels). This type of interdisciplinary longitudinal research is critical to better understand community processes in the face of disasters and ultimately provide data and inform best practices for enhancing resilience to natural hazards in US communities. This paper describes the development and implementation of this interdisciplinary effort and offers an example of combining an engineering assessment of flood damage to residential structures and social science data to model household dislocation. Dislocation probabilities were primarily driven by flooding damage but also varied significantly among Lumberton's racial/ethnic populations and by tenure.Conference paperPublication Restricted Flood performance and dislocation assessment for Lumberton homes after Hurricane Matthew(Seoul National University, 2019-05-26) Deniz, Derya; Sutley, E. J.; van de Lindt, J. W.; Peacock, W. G.; Rosenheim, N.; Gu, D.; Mitrani-Reiser, J.; Dillard, M.; Koliou, M.; Hamideh, S.; Civil Engineering; DENİZ, DeryaIn order to better understand community resilience following a disaster, a multidisciplinary research team from the Center of Excellence (CoE) for Risk-Based Community Resilience Planning and the National Institute of Standards and Technology (NIST) jointly conducted a series of longitudinal field studies in the U.S. city of Lumberton, North Carolina following major flooding from Hurricane Matthew (2016). Damage surveys on structures and interviews with households were conducted during the first field study to explore physical, economic, and social impacts of major riverine flooding on this small, tri-racial community. This paper is focused on damage to housing and subsequent household dislocation. Empirical damage fragilities were developed for residential buildings using a comprehensive set of engineering damage inspection data collected by the team. Multi-variate models were developed to assess the consequences of physical damage to housing units for household dislocation, including socio-demographic factors. The goal was not to develop the definitive model of household dislocation, but rather to show how engineering and social science data can be combined to better understand the broader social impacts of disasters - in this case, household dislocation. This study may help inform assessments of flood damage and dislocation patterns for other U.S. communities as a function of construction, social, and economic makeup.Conference paperPublication Open Access Composite cold-formed steel rubberised concrete building framed systems(Avestia Publishing, 2022) Iraguha, Dieudonne; Deniz, Derya; Sabbagh, A. B.; Torabian, S.; Jafarifar, N.; Civil Engineering; DENİZ, Derya; Iraguha, DieudonneIn this research, with the use of cold-formed steel (CFS) sections in-filled with rubberized concrete (RuC), a new low-carbon construction system is developed and assessed for its structural resilience and environmental impact compared to the current conventional earthquake-proof construction. First, connection level moment-rotation responses of the new form of CFS-RuC framed structure are validated against the results obtained from detailed finite element analyses. Next, nonlinear pushover analyses are undertaken on the CFS-RuC framed system in conjunction with conventional hot-rolled steel and reinforced-concrete (RC) frames for a case study selected in Istanbul. Lastly, economic and environmental impact analyses are conducted on the frame systems. The results show that the new CFS-RuC composite system offers both structural and environmental advantages compared to conventional systems. In terms of seismic performance of multi-storey buildings, it is shown that the ductility capacity of the CFS-RuC system can be improved by increasing the number of stories.ArticlePublication Metadata only Field reconnaissance on seismic performance and functionality of Turkish industrial facilities affected by the 2023 Kahramanmaras earthquake sequence(Springer, 2024-01) Sağbaş, Gülşah; Garjan, Ramin Sheikhi; Sarıkaya, Mahmut Kerem; Deniz, Derya; Civil Engineering; DENİZ, Derya; Sağbaş, Gülşah; Garjan, Ramin Sheikhi; Sarıkaya, Mahmut KeremOn February 6th, 2023, an earthquake sequence with moment magnitudes (Mw) of 7.8 and 7.5 rocked southern and eastern Turkiye, affecting 15 million-residents and a significant portion of Turkiye’s industrial community. In the days following the earthquake sequence, a reconnaissance team was organized to visit the industrial districts in the five provinces of the earthquake region. While performance and functionality of 131 industrial facilities were inspected using the proposed data-collection protocols, 18 interviews with industrial representatives were conducted. The inspection and interview results show that the earthquake sequence had a significant impact on industrial facilities, resulting in enormous economic losses and business disruptions lasting three months to two years. While the sequence imposed severe demands on the facilities, their poor performance is mostly due to discrepancies between seismic design code requirements and building practice. The most affected facilities were found to be those built before 2000, as well as precast reinforced concrete structures with pin-supported roofs. As a result, these types of facilities in earthquake-prone areas are strongly advised to be re-evaluated. Furthermore, various nonstructural building components, such as claddings and equipment/machinery, were substantially damaged at the majority of the assessed sites, causing lengthy interruptions. To reduce future seismic losses and disruptions to industry, the proposed protocols and findings of this field study can be utilized to support further resilience studies on the development of business continuity plans and risk management approaches for industrial facilities.ArticlePublication Metadata only Assembly-based flood repair cost and time models for industrial buildings in Turkey(Elsevier, 2023-10) Ölmez, Hasan Numan; Deniz, Derya; Civil Engineering; DENİZ, Derya; Ölmez, Hasan NumanFlooding is one of the most frequent hazard events significantly affecting the industry in Turkey, leading to severe economic losses and business disruptions. To predict the direct flood losses and business downtimes on the industry, this study proposes probabilistic cost and time models of repairing direct physical flood damage to industrial buildings in Turkey. Using field notes and literature reviews, a typical industrial building was first disassembled into a list of building components vulnerable to flooding. With a focus on façade and interior building components, the flood damage potential of each component was assessed at different flood depths and velocities. Damage state relationships were established for the building components to connect their damage levels under flood actions to their individual repair work. Using the assembly-based approach, costs and times of repairing each flood-damaged component and their associated variabilities were assembled in a probabilistic approach to develop total flood repair cost and time models. The results show that typical repair costs and times for facilities subjected to significant flood depths and velocities might reach substantial levels, up to 28% of building replacement costs and 165 working days on average. The proposed models systematically incorporate existing important uncertainties, therefore, provide reliable estimates.ArticlePublication Metadata only The effect of triaxiality on finite element deletion strategies for simulating collapse of full-scale steel structures(Elsevier, 2020-05-01) Saykin, V. V.; Nguyen, T. H.; Hajjar, J. F.; Deniz, Derya; Song, J.; Civil Engineering; DENİZ, DeryaCollapse prediction of steel structures should incorporate a finite element model that accounts for ductile fracture through material separation in critical structural members. Finite element deletion approaches have been used successfully in the past to account for fracture in steel members. However, the current common approach in collapse modeling of steel structures, a constant critical strain strategy (CS), typically requires recalibration when used with different structural configurations due to the fact that it does not account for triaxiality, which is a primary parameter in ductile fracture. To better predict structural response of steel structures undergoing collapse, it is important to study the effect of triaxiality on fracture in steel structures. A new finite element deletion approach that accounts for triaxiality was previously proposed, calibrated, and validated in small steel specimens for use in predicting collapse of steel structures. In this approach, fracture initiation is modeled using Void Growth Model (VGM) and the subsequent softening of the material to element deletion is modeled by a Hillerborg model. This paper describes the change of triaxiality, equivalent plastic strain, and other parameters during the duration of the loading, influencing the strategies implemented and provides explanation for the performance shown. In addition, the paper examines the effect of triaxiality on accurately predicting fracture in steel structures through comparison of VGM to CS strategy with validation in simulations of full-scale structural steel connection and frame tests without recalibration. The VGM strategy provided an accurate prediction based on calibration to test results that are most widely available for different types of structural steels, while CS strategy frequently provided less accurate results. The VGM strategy thus allows for an accurate collapse modeling of steel structures for use by researchers, code developers, and practitioners who address collapse of steel structures.