Civil Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/312

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2D non-linear seismic response of the Dinar basin,TURKEY
(Elsevier, 2016-10) Khanbabazadeh, H.; Iyisan, R.; Ansal, Mustafa Atilla; Hasal, M. E.; Civil Engineering; ANSAL, Mustafa Atilla
Local geological conditions generate significant amplification of ground motion and concentrated damage during earthquakes. The highly concentrated damages at the edges of the Dinar basin during occurred earthquakes at regions close to rock outcrop bring up the effect of the inclined bedrock effect on the dynamic behavior of the basin with 2D geometry. In this study, first the idealized 2D model of the basin based on the results of the underground explorations and geologic investigations is proposed. Results show that Dinar basin has an asymmetric 2D geometry with two different bedrock angles at edges. Then, a numerical study using finite difference based nonlinear code which utilizes appropriate static and dynamic boundary conditions, and includes hysteresis damping formulation based on the user defined degradation curves is conducted using real earthquake motions of different strength and frequency content. The constructed model is subjected to the collection of 16 earthquakes with different PGA's of 0.1, 0.2, 0.3 and 0.4 g, four motions for each PGA. It was seen that the dynamic behavior of the basin is broadly affected by the two dimensional bedrock. The results indicates the higher effect of the 6° bedrock inclination at east part on the amplification with respect to the steeper 20° bedrock slope at the west. Also, the results show the insignificant effect of the bedrock at the depth more than 150 m on the amplification of the east edge. While the effect of the 6° bedrock angle at the east part continues until 1500 m from the outcrop, it affects the amplification until 700 m from the outcrop at the west part with 20° bedrock angle.
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Analysis of offshore wind turbine by considering soil-pile-structure interaction: effects of foundation and sea-wave properties
(Taylor & Francis, 2022) Fard, Maryam Massah; Erken, A.; Erkmen, Bülent; Ansal, Mustafa Atilla; Civil Engineering; FARD, Maryam Massah; ERKMEN, Bülent; ANSAL, Mustafa Atilla
Prediction of the dynamic performance of an offshore wind turbine (OWT) requires consideration of many different design parameters. Besides the superstructure, the OWT foundation also plays an important role both functionally and financially in the design. In this study, numerical dynamic analyses of an offshore wind turbine with a monopile foundation are performed under wave loading that may lead to soil liquefaction around the pile due to cyclic stresses induced by the pile displacements using the open-source program, OpenSees. Effects of foundation properties such as monopile diameter, pile embedment depth, and sea-wave characteristics such as its period, sea-water depth, duration, and level of the loading on the dynamic performance of the system are investigated. The results in terms of deformations, excess pore water pressure, and inertial forces are presented and discussed. The findings are considered as valuable guidance on the estimation of the dynamic performance and liquefaction susceptibility of the offshore wind turbine foundations under cyclic sea-wave loads.
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Analysis of the benefits, challenges and risks for the integrated use of BIM, RFID and WSN: A mixed method research
(Emerald Publishing Limited, 2023-07-11) Seyis, Senem; Sönmez, A. M.; Civil Engineering; KAZAZOĞLU, Senem Seyis
Purpose: The purpose of this study is to identify, classify and prioritize the benefits, challenges and risks for the integrated use of building information modeling (BIM), radio frequency identification (RFID) and wireless sensor network (WSN) in the architecture, engineering, construction and operation (AECO) industry. Design/methodology/approach: This study relies on the mixed method approach which consists of systematic literature review, semistructured interviews and Delphi technique. A systematic literature review was performed and face-to-face semistructured interviews with seven subject matter experts (SMEs) were conducted for identification and classification purposes. Delphi method was applied in two structured rounds with eleven SMEs for prioritization purpose. These three research techniques were chosen to reach the most accurate data by combining different perspectives on the subject matter. Data gathered by these three methods was triangulated to increase the validity and reliability of this research. Findings: Thirteen benefits, ten challenges and four risks for the integrated use of BIM, RFID and WSN were identified. The results could aid the practitioners and researchers comprehend the pros and cons of this integration by representing SMEs’ valuable insights and perspectives about the current and future status, trends, limitations and requirements of the AECO industry. The identified risks and challenges show the requirements for future studies while the benefits demonstrate the capabilities and the potential contributions of this hybrid integration to the AECO industry. Originality/value: The integration of BIM, RFID and WSN is still not commonly implemented in the AECO industry. Some studies focused on this topic; however, none of them reveals the benefits, risks and challenges for integrating BIM, RFID and WSN in a holistic manner. This research makes a significant contribution to the AECO literature and industry by uncovering the benefits, challenges and risks for the integrated use of BIM, RFID and WSN that could increase industry applications.
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Analyzing the benefits and challenges of building information modelling and life cycle assessment integration
(IEEE, 2020) Azizoğlu, B.; Seyis, Senem; Civil Engineering; Ofluoğlu, S.; Özener, O. Ö.; Işıkdağ, Ü.; KAZAZOĞLU, Senem Seyis
Previous studies show that the architecture, engineering and construction (AEC) industry contributes up to 1/3 of global GHG emissions. With the aim of mitigating negative impacts of AEC industry on the natural environment, the integrated use of advanced technological instruments has been increasing in the last decade. The integration of Building Information Modelling (BIM) and Life Cycle Assessment (LCA), which is one of the cutting-edge technological instruments, provides reduction of the total time spent and the improvement of the application while minimizing the environmental impacts throughout the life cycle of the facility. The main objective of this research study is to identify the benefits and challenges of BIM and LCA integration. In order to achieve the research objective of this study, a comprehensive literature review was conducted. Twenty-two types of benefits and seven types of challenges were identified for the integrated use of BIM and LCA in the AEC industry. The major contribution of this study is a comprehensive identification of the benefits and challenges of BIM-LCA integration. The results of this study may contribute to an increase in the utilization of the BIM-LCA integration in the AEC industry that in return allows decreasing negative environmental impacts of buildings through their life-cycle.
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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 Numan
Flooding 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.
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Automated flow rate control of extrusion for 3D concrete printing incorporating rheological parameters
(Elsevier, 2024-04) Ahi, Oğulcan; Ertunç, Özgür; Bundur, Zeynep Başaran; Bebek, Özkan; Civil Engineering; Mechanical Engineering; ERTUNÇ, Özgür; BUNDUR, Zeynep Başaran; BEBEK, Özkan; Ahi, Oğulcan
The use of inline quality assessment technologies is of great importance in meeting the consistent extrusion requirements of 3D concrete printing (3DCP) applications. This paper presents a system to regulate extrusion speed and maintain the flow rate at a target value during 3DCP processes. The system is based on a new equation that combines printing parameters and the material's rheological properties in the printing process. The proposed control strategy is designed to effectively function with various cement-based mixtures. Validation tests demonstrate that the proposed system can maintain an instantaneous flow rate within a certain range and eventually achieve a constant flow rate. During operation, the flow rate is consistently maintained around the targeted value with an average error rate of 6.7 percent. The flow rate control mechanism shows promise as a reliable and efficient solution for achieving precise and constant flow rates, regardless of the cement mix design used.
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Automatic identification of roadway horizontal alignment information using geographic information system data: CurvS tool
(Sage, 2022) Bartın, Bekir Oğuz; Demiroluk, S.; Ozbay, K.; Jami, Mojibulrahman; Civil Engineering; BARTIN, Bekir Oğuz; Jami, Mojibulrahman
This paper introduces CurvS, a web-based tool for researchers and analysts that automatically extracts, visualizes, and analyses roadway horizontal alignment information using readily available geographic information system roadway centerline data. The functionalities of CurvS are presented along with a brief background on its methodology. The validation of its estimation results are presented using actual horizontal alignment data from two different roadway types: Route 83, a two-lane two-way rural roadway in New Jersey and I-80, a freeway segment in Nevada. Different metrics are used for validation. These are identification rates of curved and tangent sections, overlap ratio of curved and tangent sections between estimated and actual horizontal alignment data, and percent fit of curve radii. The validation results show that CurvS is able to identify all the curves on these two roadways, and the estimated section lengths are significantly close to the actual alignment data, especially for the I-80 freeway segment, where 90% of curved length and 94% of tangent section length are correctly matched. Even when curves have small central angles, such as the ones in Route 83, CurvS’s estimations covers 71% of curved length and 96% of tangent section length.
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Bacteria-based concrete
(Elsevier, 2018) Belie, N. de; Wang, J.; Bundur, Zeynep Başaran; Paine, K.; Civil Engineering; BUNDUR, Zeynep Başaran
Several strains of bacteria can induce the precipitation of calcium carbonate, if the appropriate conditions, sufficient nutrients and a calcium source are provided. The metabolic pathway that is followed by the bacterial strain will dictate the type of nutrients to be selected. This precipitation ability has been investigated during recent decades to improve the mechanical properties and durability of construction materials. Starting with applications for the consolidation of natural stones in weathered cultural heritage buildings and the consolidation of sandy soils, the research efforts have moved towards applications in concrete. When bacteria are mixed into fresh concrete, viable cell numbers rapidly decrease with time. Still, positive effects on concrete strength have been reported. To improve the survival rate of bacteria in concrete, various encapsulation and immobilization strategies have been explored and bacterial spores have been used instead of vegetative cells. Furthermore, added nutrients may impair concrete properties and may also be encapsulated for this reason. Encapsulated bacterial spores have shown the ability to self-heal cracks in concrete and first in-situ applications have been launched.
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Behavior of columns of steel plate shear walls with beam-connected web plates
(Elsevier, 2018-10-01) Özçelik, Ahmet Yiğit; Clayton, P. M.; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls with beam-connected web plates (B-SPSWs) are an alternative configuration of steel plate shear walls (SPSWs) where web plates are connected to the beams only. Detaching web plates from columns and introducing simple beam-column connections in B-SPSWs eliminate flexural demands in the columns resulting from web plate tension field action; consequently, the columns of B-SPSWs are designed primarily for axial loads. A recent study, however, showed that the columns of B-SPSWs resist significant flexural demands during earthquake shaking due to differential interstory drifts that result in significant column rotations at floor levels. Typical design methods (i.e., the Equivalent Lateral Force method and Modal Response Spectrum analysis) do not capture these rotations associated with differential drifts that might lead to column instability. A two-phase numerical study is conducted to evaluate the behavior and stability of B-SPSW columns. In the first phase, three-dimensional nonlinear response-history analyses are conducted to investigate the column stability for eighteen B-SPSWs with different geometric characteristics designed following two design approaches. The results suggest that column buckling is a possible mode of failure for one of the design approaches. In the second phase, a parametric study is undertaken to further investigate potential column buckling failure modes in B-SPSW columns and to establish an upper-bound estimate for the column buckling strength reduction due to column rotations at floor levels that are not considered in traditional design approaches.
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BIM-based automated safety review for fall prevention
(Springer, 2020) Tekbaş, Gökhan; Işın, Gürşans Güven; Civil Engineering; IŞIN, Gürşans Güven; Tekbaş, Gökhan
The construction industry is globally known as one of the most hazardous industries. Safety in construction is affected by many factors such as the behavior of workers, site conditions, the design and the implementation of the safety measures. Falls from height and hits by moving or falling objects are the most common types of accidents at construction sites and lead to serious injuries and fatalities. Researchers have been looking for solutions to reduce fall incidents at construction sites. Health and safety (H&S) experts usually follow traditional methods to plan and employ safety measures at sites. These safety planning methods are mainly based on reviewing 2D drawings to identify the risks and associated hazards and have some important deficiencies. First of all, the efficiency of safety planning depends on the experience of H&S experts. More importantly, it is difficult to identify the potential hazards from a 2D drawing while the project is progressing. Building Information Modeling (BIM) can overcome the challenges observed with the traditional safety planning processes. Hazards in a project and the related safety measures should be continuously identified throughout the construction. Since BIM is a 3D model-based process that assists the stakeholders not only to construct and manage but also to plan and design structures; BIM can provide an efficient solution to plan and design the safety measures of a construction project both during the design and construction phases. In addition, the safety review of buildings can be more effectively performed with a 3D building information model. In this study, “Automatic Fall Safety Review (AFSR)” rule checking tool is developed by using Dynamo, the open-source visual programming add-in for Autodesk Revit. This tool analyzes a 3D building model in Revit, and automatically identifies the hazardous places in a building and shows the related safety measures for preventing falls from height in particular. This paper presents the details of the AFSR tool and demonstrates its application for an 8-storey residential building.
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Bio-derived rheology modifying agents for cement-based materials
(Springer, 2020) Azima, M.; Bundur, Zeynep Başaran; Civil Engineering; BUNDUR, Zeynep Başaran
In recent few years, significant development has been made in concrete technology to accommodate the requirements of high-performance concrete. Rheology Modifying Agents (RMAs) (such as superplasticizers) and Viscosity Modifying Agents (VMAs) have been developed as two alternative admixtures to obtain the required workability. However, these admixtures not only increased the environmental impacts of concrete production but also increased the unit cost of concrete. Following these concerns, several studies have been focusing on exploring more sustainable approaches in concrete production such as the use of bio-based admixtures in concrete production. Throughout the literature, bio-based polysaccharides (cellulose, chitosan, etc.) were found to be highly effective as VMAs. Long chain molecules of these polysaccharides stick to the water molecules, decrease their relative motion and forms a gel, so increase the yield stress and plastic viscosity. This behaviour reduces the bleeding and segregation, which results in robust highly workable concrete. The interest in this study was motivated by the vital demand to introduce a greener and more sustainable VMA to improve the rheological properties of cement paste. To this end, bacterial cells proposed as VMAs for cement-based materials. The bacterial cells were directly incorporated into the mix of water without any additional intervention. The rheological measurements were implemented to evaluate the influence of cells on apparent viscosity and yield strength. In addition, the use of superplasticizers and fly ash on the performance of biological VMA were also investigated. Our results showed that the apparent viscosity and yield stress of the cement-paste mix were increased with the addition of the microorganisms. Moreover, bacterial cells were found to be compatible with the use of both fly ash and superplasticizers.
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Biomineralization in self-healing cement-based materials: investigating the temporal evolution of microbial metabolic state and material porosity
(American Society of Civil Engineers, 2017) Bundur, Zeynep Başaran; Bae, S.; Kirisits, M. J.; Douglas Ferron, R.; Civil Engineering; BUNDUR, Zeynep Başaran
The potential for self-healing of concrete via biomineralization processes in which microorganisms influence mineral precipitation is promising. To embed microorganisms within a cement-based material, key challenges are to find a microorganism that can tolerate the highly alkaline conditions, survive the mixing process, and remain viable with limited access to nutrients. The focus of this work is to determine the metabolic state of unencapsulated Sporosarcina pasteurii, inoculated vegetatively, in a cement-based matrix over time and to examine its ability to remediate internal cracks and reduce porosity. Viable S. pasteurii was found in hardened mortar samples that were as old as 330 days, and 48% of the viable cells detected were vegetative. A greater fraction of the inoculated cells remained viable in mortar as compared to cement paste, which is promising because mortar is a better representation of the composite nature of concrete than cement paste. Furthermore, as compared to neat paste and neat mortar, addition of the vegetative cell culture to bacterial paste and bacterial mortar resulted in reduced porosity. Bacterial mortar also demonstrated increased strength recovery as compared to neat mortar. The reduction in porosity and increase in mechanical regains demonstrated by the bacterial mortar suggest improved durability and service life for bioconcrete as compared to traditional concrete.
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Biomineralized cement-based materials: impact of inoculating vegetative bacterial cells on hydration and strength
(Elsevier, 2015-01) Bundur, Zeynep Başaran; Kirisits, M. J.; Ferron, R. D.; Civil Engineering; BUNDUR, Zeynep Başaran
Biomineralization in cement-based materials has become a point of interest in recent years due to the possibility that such an approach could be used to develop a self-healing cement-based system. The objective of this study was to investigate the impact of vegetative cells of Sporosarcina pasteurii on the hydration kinetics and compressive strength of cement-based materials. The hydration kinetics were greatly influenced when a bacterial solution consisting of urea-yeast extract nutrient medium and vegetative cells was used to prepare bacterial cement pastes; specifically, severe retardation was observed. In addition, an increase in calcium carbonate precipitation, particularly calcite, occurred within the bacterial pastes. Furthermore, after the first day of hydration, the bacterial mortar displayed compressive strength that was similar to or greater than the compressive strength of the neat mortar.
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Blind identification of site effects and bedrock motion from surface response signals
(Elsevier, 2018-04) Ghahari, S. F.; Abazarsa, F.; Jeong, C.; Kurtuluş, Aslı; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
A method for blind identification of site effects from two nearby ground surface response signals is presented. The proposed approach makes use of ground surface accelerations from two nearby stations to back-calculate the transfer functions of both sites and their common bedrock motion. Seismic analysis of structures cannot be carried out accurately unless site effects are taken into account. Moreover, presently available empirical attenuation relationships for predicting ground surface motions are only useful if site effects are considered. While an extensive collection of analytical and numerical techniques is available to analyze ground responses induced by bedrock motions, their accuracy depends on a priori knowledge of site properties and the availability of bedrock motions. There are techniques based on direct/indirect measurements—such as spectral analysis of surface waves (SASW), and material testing of borehole samples—however, responses predicted by their output do not necessarily reflect site behavior during strong motions. As such, the estimation of site response from acceleration data recorded on the ground surface during real-life events is a key capability. In the method proposed herein, the site response is identified from recorded ground surface accelerations at two nearby stations through a blind identification technique, under the assumption that the unknown bedrock motion is identical for both stations and those two stations have different transfer functions. Most of the existing site response identification methods rely on a strategically chosen reference station, and the present approach obviates this limitation. We demonstrate the performance of this new approach using a synthetic, but adequately realistic, example.
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Calcium sulfoaluminate cement and supplementary cementitious materials-containing binders in self-healing systems
(Elsevier, 2023-08) Acarturk, B. C.; Sandalcı, Ilgın; Hull, N. M.; Bundur, Zeynep Başaran; Burris, L. E.; Civil Engineering; BUNDUR, Zeynep Başaran; Sandalcı, Ilgın
Creation of more durable concrete is one pathway to achieving improved sustainability and carbon footprint over a concrete structure's life. Microbially induced calcite precipitation has been shown to densify concrete microstructure and fill cracks, reducing moisture transport. One challenge associated with the longevity of bacterial-concrete systems is the high pH environment of the cement paste. Herein, two approaches to address this challenge were investigated: (i) sustainable binder systems, such as calcium sulfoaluminate (CSA) cement and fly ash substitutions of ordinary portland cement (OPC), which lead to lower pH systems, and (ii) non-axenic bacterial cultures, which may facilitate growth of more alkaline-resistant bacteria. Mechanical properties, water absorption, self-healing ability, and survivability of the bacterial systems were tracked, finding that incorporation of non-axenic bacteria did not result in increased bacteria survivability compared to axenic bacteria. However, both bacteria healed cracks [removed]
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Characterization of site amplification by a parametric study
(Taylor & Francis, 2023) Fercan, N. O.; Şafak, E.; Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
The reliability of Vs30 and the performance of alternative time averaged shear wave velocities (Vsz) and shear wave travel times (Ttz) at various depths, z, were investigated for the estimation of site amplification and fundamental frequency (f 0) characterization by considering the linear and nonlinear soil behavior. The study revealed that alternative parameters performed better than Vs30 and the best performing z parameters changed by switching from convex to concave theoretical profiles and by increasing ground motions. For a practical usage in site investigations, guidelines to estimate nonlinear soil amplification factor and fundamental frequency from the linear ones were presented.
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A comparative evaluation of sepiolite and nano-montmorillonite on the rheology of cementitious materials for 3D printing
(Elsevier, 2022-10-03) Aydın, Eylül Mina; Kara, Ahmet Burhan; Bundur, Zeynep Başaran; Özyurt, N.; Bebek, Özkan; Gulgun, M. A.; Civil Engineering; Mechanical Engineering; BUNDUR, Zeynep Başaran; BEBEK, Özkan; Aydın, Eylül Mina; Kara, Ahmet Burhan
Through the last decade, methods of digital manufacturing of concrete gained a significant interest compared to conventional concrete. The main challenge in additive manufacturing (3D printing) is to design a highly thixotropic cementitious system. This study aims to investigate the use of sepiolite as a rheology modifier as a novel approach to improve the thixotropic behavior and adapt cementitious systems to 3D printing. To understand the influence of sepiolite on rheological properties, a comparative evaluation with nano-montmorillonite was established. The effectiveness of clay addition was also investigated in fly-ash amended cement-based materials. The rheological analysis was done on cement-paste samples containing both clays in terms of their effects on thixotropy, structural build-up, and recovery. A preliminary printability assessment was done with a lab scale printer having a ram extruder. The results show that the incorporation of clays increased the dynamic yield stress and time-dependent evolution of static yield stress. Moreover, the addition of clays improved the thixotropic behavior of cement-based systems, particularly those containing fly-ash. Herein, the sepiolite was found to be more effective compared to nano-montmorillonite in terms of improving thixotropy, structural build-up and recovery. The results showed that use of fly-ash enhances the printability of the mix for the specified extruder and the samples containing 1% nano-montmorillonite or 0.5% sepiolite can be printed. The positive effects of sepiolite were attributed to opposing surface charges of the clay layers and its micro-fibrous microstructure. The findings in this study enabled an in-depth understanding of the rheology and printability of fly-ash amended clay containing printable cement-based mortars.
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A comparison study between 1D and 2D site response analyses based on observed earthquake acceleration records
(Springer, 2023) Shamekhi, Shima; Ansal, Mustafa Atilla; Kurtuluş, Aslı; Civil Engineering; ANSAL, Mustafa Atilla; KURTULUŞ, Asli; Shamekhi, Shima
The objective of the present work is to evaluate the necessity of 2D site response analysis based on the comparison among the peak ground and spectral accelerations recorded by Istanbul Rapid Response Network and Istanbul vertical array stations during the Mw = 6.5 24/5/2014 Gökçeada and Mw = 5.9 19/5/2011 Kütahya earthquakes with the calculated accelerations by 1D and 2D site response analyses. The shear wave velocity profiles determined based on in-situ geophysical and geotechnical measurements and laboratory tests within the Istanbul Microzonation Project are revaluated adopting a revision scheme to obtain the best fits between the recorded and calculated spectral accelerations by 1D site response analysis. These modified shear wave velocity profiles are later used for 1D and 2D site response analyses performed in North–South and East–West directions to model peak ground and spectral accelerations on the ground surface. Finally, by modelling different distances around boreholes the influence of variation of the soil profile in horizontal direction is investigated by 2D analyses.
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A comparison study between 1D and 3D site response analyses based on observed earthquake acceleration records…
(National Technical University of Athens, 2023) Shamekhi, Shima; Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla; Shamekhi, Shima
The characteristics of the site conditions have a very significant influence on the variation of building damage during earthquakes, thus, it is essential to evaluate and analyse the effects of site conditions. One option is to conduct site-specific response analysis to calculate the response of the soil layers by using estimated acceleration records on rock outcrop, shear wave velocity profiles, shear modulus reduction, and damping ratio curves as inputs for the encountered soil layers. The objective of the present work is to evaluate the necessity of 3D site response analysis based on the comparison among the peak ground and spectral accelerations recorded by Istanbul Rapid Response Network and Istanbul vertical array stations during the Mw=6.5 24/05/2014 Gökçeada and Ml=5.7 26/09/2019 Silivri earthquakes with the calculated accelerations by 1D and 3D site response analyses. The shear wave velocity profiles determined based on in-situ geophysical and geotechnical measurements and laboratory tests within the Istanbul Microzonation Project are revaluated adopting an optimization scheme to obtain the best fits between the recorded and calculated accelerations by 1D site response analysis. These modified shear wave velocity profiles are later used for 3D site response analyses performed taking into consideration the three components of the recorded acceleration time histories in all three directions at the bedrock level to model peak ground and spectral accelerations on the ground surface.
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A computational workflow for rupture‐to‐structural‐response simulation and its application to Istanbul
(Wiley, 2020-10) Zhang, W. Y.; Restrepo, D.; Crempien, J. G. F.; Erkmen, Bülent; Taborda, R.; Kurtuluş, Aslı; Taciroglu, E.; Civil Engineering; ERKMEN, Bülent; KURTULUŞ, Asli
Scenario-based earthquake simulations at regional scales hold the promise in advancing the state-of-the-art in seismic risk assessment studies. In this study, a computational workflow is presented that combines (i) a broadband Green's function-based fault-rupture and ground motion simulation-herein carried out using the "UCSB (University of California at Santa Barbara) method", (ii) a three-dimensional physics-based regional-scale wave propagation simulation that is resolved at fmax=11.2 Hz, and (iii) a local soil-foundation-structure finite element analysis model. These models are interfaced with each other using the domain reduction method. The innermost local model-implemented in ABAQUS-is additionally enveloped with perfectly matched layer boundaries that absorb outbound waves scattered by the structures contained within it. The intermediate wave propagation simulation is carried out using Hercules, which is an explicit time-stepping finite element code that is developed and licensed by the CMU-QUAKE group. The devised workflow is applied to a 80x40x40 km3 region on the European side of Istanbul, which was modeled using detailed soil stratigraphy data and realistic fault rupture properties, which are available from prior microzonation surveys and earthquake scenario studies. The innermost local model comprises a chevron-braced steel frame building supported by a shallow foundation slab, which, in turn, rests atop a three-dimensional soil domain. To demonstrate the utility of the workflow, results obtained using various simplified soil-structure interaction analysis techniques are compared with those from the detailed direct model. While the aforementioned demonstration has a limited scope, the devised workflow can be used in a multitude of ways, for example, to examine the effects of shallow-layer soil nonlinearities and surface topography, to devise site- and structure-specific seismic fragilities, and for calibrating regional loss models, to name a few.

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