Civil Engineering

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

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Local site conditions and seismic risk assessment of historic buildings
(2013) D’Ayala, D.; Ansal, Mustafa Atilla; Civil Engineering; Bilotta, E.; Flora, A.; Lirer, S.; Viggiani, C.; ANSAL, Mustafa Atilla
The objectives of the Istanbul Seismic Risk Mitigation and Emergency Preparedness Project are to improve Istanbul’s preparedness for a potential earthquake. Within this framework “Risk Assessment of Cultural Heritage Buildings” was designed to address the vulnerability of cultural assets, specifically buildings with global cultural heritage value. One of the components of the project was the vulnerability and risk assessment of 170 historic buildings of varied age, value and state of conservation, distributed over several square miles. Many of these buildings have public functions such as museums or education establishments. Among the most famous are Topkapı Palace and Hagia Irene museum. After a discussion of the choice of the most appropriate earthquake scenario, the methodology used for assessing the effects of local site conditions on the seismic performance of selected cultural heritage buildings is presented. The purpose is to estimate the earthquake characteristics on the ground surface based on the probabilistic and deterministic hazard studies. The site specific elastic design spectra for each site are then manipulated to obtain site specific nonlinear displacement spectra, so that these can be directly compared with capacity curves for the buildings obtained by using mechanism approach limit state analysis. The procedure for obtaining the capacity curves is described and the choice of the most appropriate level of ductility and the equivalent reduction coefficient are discussed. A procedure to evaluate performance points and to define safety factors based on lateral acceleration, drift or expected damage level, is presented. The process of arriving at a risk evaluation and hence recommendation for strengthening or otherwise, is finally highlighted with respect to four comparable case studies.
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Eulogy to Professor Nicholas N. Ambraseys
(Springer Science+Business Media, 2013-02) Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
Sadly, at the final phase of all these preparations for Vol.11 N.1, our very dear and very distinguished Editorial Board Member Prof. Nicholas Ambraseys passed away on December 28, 2012 at the age of 83. Prof. Ambraseys played a very positive and crucial role in the initiation of the Bulletin of Earthquake Engineering ten years ago. He attended the EAEE Executive Committee Meeting held in Lisbon on September 16, 2000 and supported the publication of a new technical journal as the official journal of EAEE. As the Editorial Board of BEE, we believe it would be very appropriate to dedicate this issue to our great mentor, colleague and great researcher, Professor Nicholas Ambraseys. He recently submitted two manuscripts to be published in BEE. The first one “Assessment of the long-term seismicity of Athens from two classical columns” was published in the V.10 N.6 (2012). The second one “Ottoman archives and the assessment of the seismicity of Greece 1456–1833” is in the review stage.
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Preface to the second decade
(Springer Science+Business Media, 2013-02) Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
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Perspectives on European earthquake engineering and seismology
(Springer Science+Business Media, 2014) Ansal, Mustafa Atilla; Civil Engineering; Ansal, Mustafa Atilla; ANSAL, Mustafa Atilla
This book collects 5 keynote and 15 topic lectures presented at the 2nd European Conference on Earthquake Engineering and Seismology (2ECEES), held in Istanbul, Turkey, from August 24 to 29, 2014. The conference was organized by the Turkish Earthquake Foundation - Earthquake Engineering Committee and Prime Ministry, Disaster and Emergency Management Presidency under the auspices of the European Association for Earthquake Engineering (EAEE) and European Seismological Commission (ESC).
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Microchip ELISA coupled with cell phone to detect ovarian cancer HE4 biomarker in urine
(Springer Science+Business Media, 2014) Wang, S.; Akbaş, Ragıp; Demirci, U.; Civil Engineering; AKBAŞ, Ragıp
Ovarian cancer is a leading cause of death from gynecologic cancers in the USA, and early diagnosis can potentially increase 5-year survival rate. Detection of biomarkers derived from hyperplasia of epithelial tissue by enzyme-linked immunosorbent assay (ELISA) proves to be a practical way of early diagnosis of ovarian cancer. However, ELISA is commonly performed in a laboratory setting, and it cannot be used in a clinical setting for on-site consultation. We have shown a microchip ELISA that detects HE4, an ovarian cancer biomarker, from urine using a cell phone integrated with a mobile application for imaging and data analysis. In microchip ELISA, HE4 from urine was first absorbed on the surface; the primary and secondary antibodies were subsequently anchored on the surface via immuno-reaction; and addition of substrate led to color development because of enzymatic labeling. The microchip after color development was imaged using a cell phone, and the color intensity was analyzed by an integrated mobile application. By comparing with an ELISA standard curve, the concentration of HE4 was reported on the cell phone screen. The presented microchip ELISA coupled with a cell phone is portable as opposed to traditional ELISA, and this method can facilitate the detection of ovarian cancer at the point-of-care (POC).
Open Access
Site response from Istanbul vertical arrays and strong motion network
(Earthquake Engineering Research Institute ( EERI ), 2014) Ansal, Mustafa Atilla; Kurtuluş, Aslı; Tonuk, G.; Civil Engineering; ANSAL, Mustafa Atilla; KURTULUŞ, Asli
In the framework of Istanbul Microzonation Project for the European side, the investigated region was divided by a grid system of 250m×250m and site investigations were performed for each cell based on borings and in-situ seismic wave velocity measurements for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock. Geological and geotechnical laboratory and field testing data with measured seismicwave velocities enabled to determine the engineering properties of the soil and rock layers encountered in all the cells. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. Even though the maximum PGA were similar, the observed spectral response were different indicating the importance of the distance and source magnitude concerning the frequency content and predominant soil period ranges. Even though the level of ground shaking intensity is relatively low, efforts were made to evaluate the variation of the recorded accelerations with depth in vertical arrays located at Ataköy, Zeytinburnu and Fatih. Attempts were also made to model the recorded acceleration time histories at the triggered IRRN stations using the acceleration records obtained at the bedrock level from the vertical array stations in the case of the recent 19.5.2011 Mw=5.7 Kütahya earthquake that took place approximately 185km away.
Open Access
Micro-a-fluidics ELISA for rapid CD4 cell count at the point-of-care
(Nature, 2014-01-22) Wang, S.; Tasoglu, S.; Chen, P. Z.; Chen, M.; Akbaş, Ragıp; Wach, S.; Ozdemir, C. İ.; Gurkan, U. A.; Giguel, F. F.; Kuritzkes, D. R.; Demirci, U.; Civil Engineering; AKBAŞ, Ragıp
HIV has become one of the most devastating pathogens in human history. Despite fast progress in HIV-related basic research, antiretroviral therapy (ART) remains the most effective method to save AIDS patients' lives. Unfortunately, ART cannot be universally accessed, especially in developing countries, due to the lack of effective treatment monitoring diagnostics. Here, we present an inexpensive, rapid and portable micro-a-fluidic platform, which can streamline the process of an enzyme-linked immunosorbent assay (ELISA) in a fully automated manner for CD4 cell count. The micro-a-fluidic CD4 cell count is achieved by eliminating operational fluid flow via “moving the substrate”, as opposed to “flowing liquid” in traditional ELISA or microfluidic methods. This is the first demonstration of capturing and detecting cells from unprocessed whole blood using the enzyme-linked immunosorbent assay (ELISA) in a microfluidic channel. Combined with cell phone imaging, the presented micro-a-fluidic ELISA platform holds great promise for offering rapid CD4 cell count to scale up much needed ART in resource-constrained settings. The developed system can be extended to multiple areas for ELISA-related assays.
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Special issue in memory of Nicholas Ambraseys
(Springer Science+Business Media, 2014-02) Douglas, J.; Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
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Site specific response analysis for performance based design earthquake characteristics
(Springer Science+Business Media, 2014-06) Tönük, G.; Ansal, Mustafa Atilla; Kurtuluş, Aslı; Çetiner, B.; Civil Engineering; ANSAL, Mustafa Atilla; KURTULUŞ, Asli
During strong earthquakes, seismic waves travelling towards the ground surface alter the engineering characteristics of the soil layers and consequently the characteristics of travelling seismic waves also change with respect to their frequency and amplitude contents. In assessing the site-specific design earthquake characteristics in seismically active zones for performance levels of Collapse Prevention, Life Safety, and Immediate Occupancy that may correspond to 72, 475 and 2475 year return period earthquakes, detailed site characterization and site response analyses may be required. This process may be conducted in two consecutive statistically independent stages. The first stage involves the seismic hazard study to assess the design earthquake characteristics on rock outcrop for selected exceedance levels and the second stage involves detailed site characterization and site response analyses to estimate design earthquake characteristics on the ground surface. The uncertainties arising from the source characteristics need to be taken into account by using a representative number of strong motion acceleration records for site response analyses recorded in locations that are compatible with the seismic hazard with respect to fault mechanism, earthquake magnitude, and source distance. In addition, the strong motion acceleration records should be compatible with respect to peak acceleration and acceleration response spectra levels estimated by the probabilistic or deterministic seismic hazard study. One approach is to use the uniform acceleration hazard spectra and another option is to adopt conditional mean spectrum on rock outcrop estimated in the first stage from the earthquake hazard study for scaling input motions for site response analysis. It was observed that the scaling methodology adopted may play an important role in the calculated earthquake characteristics on the ground surface. A semi empirical procedure was proposed to determine the site specific design earthquake characteristics on the ground surface. A parametric study was conducted to demonstrate the applicability of the proposed methodology based on one dimensional site response analyses using Shake91 and DeepSoil site response codes to evaluate design earthquake characteristics on the ground surface.
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Use of biomineralisation in developing smart concrete inspired by nature
(Inderscience, 2015) Zhang, B.; Bundur, Zeynep Başaran; Mondal, P.; Ferron, R. D.; Civil Engineering; BUNDUR, Zeynep Başaran
Recently, interest has focused on leveraging the biological functions of microorganisms to develop smart cement-based materials. This paper provides an overview of the calcium carbonate biomineralisation process in nature and presents a review of the work conducted by various groups around the world on biogenic calcium carbonate formation as it relates to the hydration, microstructure, properties, and performance of cement-based materials. Promises and concerns of applying biomineralisation in cement-based materials are also discussed, and directions for future research are explored.
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Editorial and welcome to a new ERA
(Springer International Publishing, 2015-01) Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
With this first issue of Volume 13 (2015), while we are celebrating our 12th anniversary, we will be implementing some major changes for BEE. We are going to start publishing on a monthly basis with 12 issues per year and introduce eight new Associate Editors. I would like to take this opportunity to welcome the eight Associate Editors who will be sharing the Editorial responsibilities.
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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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Eulogy to Professor Michele Maugeri
(2015-01) Silvestri, F.; Pitilakis, K.; Ansal, Mustafa Atilla; Civil Engineering; ANSAL, Mustafa Atilla
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Observations from geotechnical arrays in Istanbul
(Springer, 2015-04-16) Kurtuluş, Aslı; Ansal, Mustafa Atilla; Tönük, G.; Çetiner, B.; Civil Engineering; KURTULUŞ, Asli; ANSAL, Mustafa Atilla
Few small earthquakes with local magnitude slightly larger than ML = 4 were recorded by geotechnical downhole arrays that have been recently deployed in the west side of Istanbul. Same events were also recorded by Istanbul Rapid Response Network (IRRN) which comprises of 55 surface strong motion stations in the European side of Istanbul. The strongest one of these earthquakes took place on 12/3/2008 in Çınarcık with local magnitude of ML = 4.8. Even though the observed PGAs were not exceeding 0.01 g, an effort is made to model the recorded response at the downhole array sites as well as the at the IRRN stations using the acceleration records obtained by the deepest sensors, i.e. on the engineering bedrock, at the downhole array sites as input bedrock motions. 1D equivalent linear site response analysis that is generally adopted for site-specific response analysis is used for modelling. Observations from the recorded response and results from 1D modelling of ground response have yielded in general good agreement between the observed and recorded soil response at the station sites.
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A probabilistic seismic hazard assessment for the Turkish territory—part I: the area source model
(Springer International Publishing, 2016) Sesetyan, K.; Demircioglu, M. B.; Duman, T. Y.; Çan, T.; Tekin, S.; Eroğlu Azak, T.; Fercan, Nazife Özge Zülfikar; Fercan, Nazife Özge Zülfikar
The seismic zoning map of Turkey that is used in connection with the national seismic design code (versions issued both in 1997 and 2007) is based on a probabilistic seismic hazard assessment study conducted more than 20 years ago (Gülkan et al. in En son verilere göre hazırlanan Türkiye deprem bölgeleri haritası, Report No: METU/EERC 93-1, 1993). In line with the efforts for the update of the seismic design code, the need aroused for an updated seismic hazard map, incorporating recent data and state-of-the-art methodologies and providing ground motion parameters required for the construction of the design spectra stipulated by the new Turkish Earthquake Design Code. Supported by AFAD (Disaster and Emergency Management Authority of Turkey), a project has been conducted for the country scale assessment of the seismic hazard by probabilistic methods. The present paper describes the probabilistic seismic hazard assessment study conducted in connection with this project, incorporating in an area source model, all recently compiled data on seismicity and active faulting, and using a set of recently developed ground motion prediction equations, for both active shallow crustal and subduction regimes, evaluated as adequately representing the ground motion characteristics in the region. The area sources delineated in the model are fully parameterized in terms of maximum magnitude, depth distribution, predominant strike and dip angles and mechanism of possible ruptures. Resulting ground motion distributions are quantified and presented for PGA and 5 % damped spectral accelerations at T = 0.2 and 1.0 s, associated with return periods of 475 and 2475 years. The full set of seismic hazard curves was also made available for the hazard computation sites. The second part of the study, which is based on a fault source and smoothed seismicity model is covered in Demircioglu et al. in Bull Earthq Eng, (2016).
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Increasing the stability of nanofluids with cavitating flows in micro orifices
(AIP, 2016) Karimzadehkhouei, M.; Ghorbani, M.; Sezen, M.; Sendur, K.; Mengüç, Mustafa Pınar; Leblebici, Y.; Kosar, A.; Mechanical Engineering; MENGÜÇ, Mustafa Pınar
One of the most critical challenges for nanofluids in practical applications is related to their stability and reusability since a gradual agglomeration of nanoparticles in nanofluids occurs with time and is accelerated by heating. In this study, we propose a technique to maintain the performance and stability of nanofluids with the use of cavitating flows through micro orifices to prevent agglomeration and sedimentation of nanoparticles, which will increase the durability of the nanofluids. γ-Al2O3 (gamma-alumina) nanoparticles with a mean diameter of 20 nm suspended in water were utilized. In the current approach, a flow restrictive element induces sudden pressure, which leads to cavitation bubbles downstream from the orifice. The emerging bubbles interact with the agglomerated structure of nanoparticles and decrease its size through hitting or shock waves generated by their collapse, thereby increasing the stability and reusability of nanofluids. The method does not involve any use of expensive surfactants or surface modifiers, which might alter the thermophysical properties of nanofluids, may adversely influence their performance and biocompatibility, and may limit their effectiveness.
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Evaluation of self-healing of internal cracks in biomimetic mortar using coda wave interferometry
(Elsevier, 2016-05) Liu, S.; Bundur, Zeynep Başaran; Zhu, J.; Ferron, R. D.; Civil Engineering; BUNDUR, Zeynep Başaran
Calcium carbonate biomineralization is a bio-chemical process in which calcium carbonate precipitation is obtained by leveraging the metabolic activity of microorganisms. Studies have shown that biomineralization can be used to repair surface cracks in cement-based materials. One of the challenges in determining whether biomineralization is a feasible option for internal crack repair pertains to how to monitor and quantify self-healing of internal microcracks. In this study, mortar samples with and without microcracks and microorganisms were cured in different environments until 50 days. Coda wave interferometry measurements, a nondestructive method that is very sensitive to small changes in material, were conducted on these samples to evaluate the extent of self-healing during the entire curing period. Compressive strength tests were performed after 7 and 28 days of curing. The results indicated that the cracked mortar samples with microorganisms showed significantly higher strength development and higher relative velocity change than samples without microorganisms.
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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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Evaluation of code provisions for seismic performance of unachored liquid storage tanks
(2017) Erkmen, Bülent; Civil Engineering; ERKMEN, Bülent
Seismic performance of two unanchored liquid-storage tanks with tank diameter of 24.5 m and 36 m and operating liquid height of 12.2 m and 20.0 m, respectively were investigated using Coupled Eulerian-Lagrangian (CEL) and mechanical spring-mass analogy nonlinear finite element computational methods. The CEL approach includes the effects of higher modes of liquid vibration (sloshing), liquid breaking effects, and liquid-structure interaction during seismic loading. The modern seismic design provisions for liquid-storage tanks, on the other hand, are based on a mechanical spring-mass analogy. This approach neglects the higher vibration modes for the sloshing water, liquid-structure interaction, and effects of tank base uplift on seismic performance. For the tanks, base uplift histories were computed with both modeling approaches through nonlinear time history analysis performed using five recorded earthquake acceleration data. The uplift histories were compared to evaluate the adequacy of code seismic design provisions for unanchored tanks, and to determine whether the mechanical spring-mass analogy can be used to predict seismic performance of unanchored tanks. Analysis results show that the traditional mechanical spring-mass analogy, which is the basis for the current seismic design provisions, does not capture tank uplift history and its effects on dynamic loads. This approach underpredicts the total numbers of tank uplifts during seismic loading. The maximum tank base uplift computed using mechanical spring-mass analogy had an average error between 22% and 58 % for each tank. The results show that there is a need to developed a modify version of the traditional mechanical spring-mass analogy to be used for predicting seismic performance of unanchored liquid-storage tanks.
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Impact of air entraining admixtures on biogenic calcium carbonate precipitation and bacterial viability
(Elsevier, 2017) Bundur, Zeynep Başaran; Amiri, Ali; Ersan, Y. C.; Boon, N.; Belie, N. de; Civil Engineering; BUNDUR, Zeynep Başaran; Amiri, Ali
The applications of self-healing in cement-based materials via biomineralization processes are developing quickly. The main challenge is to find a microorganism that can tolerate the restricted environment of cement paste matrix (i.e. very high pH, lack of oxygen and nutrients, small pore size etc.). The focus of this work was to determine the possible use of an ammonium salt-based air-entraining admixture (AEA) as a protection method to improve the survival of incorporated Sporosarcina pasteurii cells in cement-based mortar. Bacterial cells were directly added to the mortar mix with and without nutrients. Nutrients should be provided to keep the microorganisms viable even at early ages (i.e. 7 days). Surface charge of the bacterial cells and in vitro biogenic calcium carbonate (CaCO3) precipitation were not affected by the incorporation of AEA. However, introducing AEA did not influence the viability in mortar samples, which might be attributed to the type and chemistry of AEA used.

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