Browsing by Author "Selcuk, Levent"

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An Approach for the Application of Energy-Based Liquefaction Procedure Using Field Case History Data
(Maden Tetkik ve Arama Genel Mudurlugu-mta, 2020) Kayabal, Kamil; Selcuk, Levent; Beyaz, Turgay
This paper presents an overview to the applicability of the "energy-based liquefaction approach" with regards to the new developments in the subject. The method involves comparing the strain energy for the soil liquefaction (capacity) with the strain energy imparted to the soil layer during an earthquake (demand) The performance of the method was evaluated by using a large database of SPT-based liquefaction case history. The energy-based method and the more commonly used stress-based method were compared in their capability to assess liquefaction potential under the same damaging historic earthquakes and geotechnical site conditions. In the procedure, the predictive strain energy equations were used to estimate the capacity energy values. These empirical equations have been developed based on the initial effective soil parameters. As for the energy of any given strong ground motion, it was computed from a velocity-time history of the ground motion and the unit mass of soil through utilization of kinetic energy concepts. The proposed energy-based method has effective way in evaluating the liquefaction potential based on the seismological parameters, contrary to the stress-based approach, where only peak ground acceleration (PGA) is considered.
An Avalanche Hazard Model for Bitlis Province, Turkey, Using Gis Based Multicriteria Decision Analysis
(Tubitak Scientific & Technological Research Council Turkey, 2013) Selcuk, Levent
Most avalanche fatalities in Turkey have occurred in Bitlis Province. The scope of this research was to identify the avalanche hazard area of that province, using geographical information system (GIS) based multicriteria decision analysis (MCDA) and to evaluate it by means of sensitivity and accuracy analysis. The model consists of 5 GIS layers: elevation, slope, aspect, vegetation density, and land use. The hazard model is obtained by using a comparison matrix where all identified criteria of GIS layers are compared against each other. The acceptability of the model was determined using historical events. All of these events plotted over the model showed that there is a remarkable coincidence with high hazard areas. Approximately 90% of avalanche events have occurred in the high and moderately high areas. Settlement areas cover approximately 39,741 ha of study area and just 41 settlement areas (villages and towns) have ideal topographic characteristics to prevent avalanche hazard, while 82% of them are not suitable. The avalanche hazard model shows that the southeast and southwest parts of Bitlis (Center), Tatvan, and Hizan counties have the highest avalanche hazard. Therefore, site planning, construction of supporting structures, and control programs should be effectively integrated with avalanche pathways in potential areas.
Detection of Near Surface Rock Fractures Using Ultrasonic Diffraction Techniques
(Techno-press, 2019) Selcuk, Levent
Ultrasonic Time-of-Flight Diffraction (TOFD) techniques are useful methods for non-destructive evaluation of fracture characteristics. This study focuses on the reliability and accuracy of ultrasonic diffraction methods to estimate the depth of rock fractures. The study material includes three different rock types; andesite, basalt and ignimbrite. Four different ultrasonic techniques were performed on these intact rocks. Artificial near-surface fracture depths were created in the laboratory by sawing. The reliability and accuracy of each technique was assessed by comparison of the repeated measurements at different path lengths along the rock surface. The standard error associated with the predictive equations is very small and their reliability and accuracy seem to be high enough to be utilized in estimating the depth of rock fractures. The performances of these techniques were re-evaluated after filling the artificial fractures with another material to simulate natural infills.
Estimation of the Compressive Strength of Concrete Under Point Load and Its Approach To Strength Criterions
(Korean Society of Civil Engineers-ksce, 2015) Selcuk, Levent; Gokce, H. Suleyman
The point load strength (I-s(50)) is an alternative mechanical parameter to predict the compressive strength of concrete. The scope of this investigation is to develop an empirical equation relating the point load strength and compressive strength of concrete. In this context, crushed limestone aggregates at two different strength levels were used in concrete mixture. Point load strength and compressive strength tests on concrete specimens which had 6 different compressive strengths were performed for each limestone aggregate. A series of regression analyses was applied using any general statistical package to evaluate the ratio of point load strength test to cube compressive strength of concrete, (I-s(50)/f cu). The accuracy and reliability of the equation in this investigation was assessed by means of the Mean Absolute Percent Error (MAPE). The relative error can be considered reasonably well for the empirical relationship. The ratio of I-s(50)/f cu was also verified by a large database collected from previous studies. The proposed equation is quite compatible with the database. Furthermore, the ratio of I-s(50)/f cu indicates significant material property of concrete and defines the material constant in strength criterions. It can be used to estimate the axial compressive strength of concrete under confining stress without performing triaxial tests, considered Hoek-Brown and Johnson empirical failure criterions.
Evaluation of the Ratio Between Uniaxial Compressive Strength and Schmidt Hammer Rebound Number and Its Effectiveness in Predicting Rock Strength
(Taylor & Francis Ltd, 2015) Selcuk, Levent; Yabalak, Esma
Schmidt rebound hammer (SRH) test has been used worldwide as an index test for estimating the compressive strength and deformation characteristics of intact rocks. Although there is a high correlation between the surface hardness and the uniaxial compressive strength (UCS) of intact rocks, the SRH provides only a crude estimate for the UCS of rocks. SRH numbers reflect the outer surface of rocks and a depth of 30-50mm. It is not sensitive to the intrinsic properties of the rocks such as texture, saturation, porosity and micro-fractures controlling the mechanical behaviour of rocks. In order for an empirical equation relating the surface hardness to the UCS to be widely used, the index parameter should characterise the mechanical properties of intact rocks. The ratio of UCS/SRH defined as a function of the UCS is a much better indicator for assessing the mechanical characteristics of rocks because the UCS of rocks defines the strength of the material and the ratio UCS/SRH is strongly affected by the level of the UCS. The ratio of UCS/SRH increases with increasing compressive strength at an increasing rate. A large-scale regression analysis was carried out using experimental data to evaluate the ratio of UCS/SRH for the rocks. The accuracy and reliability of the relationship was assessed by means of the root mean square error. The standard error associated with the empirical relationship is very small and the reliability and accuracy of the relationship to assess the compressive strength indirectly seem to be higher than those of traditional relationships between the UCS and the SRH. The ratio of UCS/SRH was also verified by a large database collected from previous studies. This strong linear relationship is proposed for engineering projects requiring the estimation of the compressive strength for intact rocks.
Evaluation of the Unconfined Compressive Strength of Rocks Using Nail Guns
(Elsevier Science Bv, 2015) Selcuk, Levent; Kayabali, Karnil
The penetration depth is one of the major index parameters for indirect determination of the unconfined compressive strength (UCS) of rock. That is, the weaker the rock, the deeper the nail penetration should be, and vice versa. However, the penetration depth depends on the strength of material, the impact energy and nail diameters of nail guns. In order for an empirical equation relating the penetration depth to the UCS to be widely used, the equation should be related to all varieties of gasnailers. The scope of this investigation is to develop an empirical equation relating the nail penetration depth (h) obtained through nail guns of different energy levels (e) and nail diameters (d) to UCS. In this context, a series of gasnailers with different energy levels and nail diameters were performed on 65 rock blocks. The results of laboratory conducted unconfined compressive test were correlated with nail penetration depth (h), nail gun energy (e) and nail diameter (d) and an empirical equation was established using multiple regression analysis. It covers a relatively wide range of energy levels and nail diameters for commercial gasnailers. The proposed equation can be used to estimate the UCS of intact rocks, thus providing the technical features needed for using commercial gasnailers. (C) 2015 Elsevier B.V. All rights reserved.
Experimental Investigation of the Rock-Concrete Bi Materials Influence of Inclined Interface on Strength and Failure Behavior
(Pergamon-elsevier Science Ltd, 2019) Selcuk, Levent; Asma, Derya
Experimental observations and measurements on strength and failure behavior of rock-concrete bi materials are important to correctly understand the response of concrete structure-rock foundation. In this context, a large number of experimental investigations have been carried out in order to identify the interaction at rock-concrete interface, but the influence of inclined interface on strength and failure behavior has not been addressed by adequate experimental studies. The main objective of this investigation is to experimentally investigate the response of the rock-concrete interface at different inclination angles. The effect of inclined interface on strength and failure behavior of rock-concrete bi specimens were investigated under uniaxial compression (UCS), splitting tensile (ST) and point loading (PLS). The variation in strength and failure patterns with respect to the inclination angles of rock-concrete interface were generally observed in all test conditions. The measured strengths and observed failure behaviors during the UCS test were compared with those obtained from ST and PLS tests. It was found that the relation between PLS and interface inclination angle is remarkable in so far as in the case ST conditions in which tensile strength vary as a function of inclination angle. However, these both indirect tests does not provide satisfactory results in determination of the strength variation of specimens when inclination angle of weakness interface starts to become parallel to the loading direction.
Frs (Fault Rating System): a Quantitative Classification of Active Faults for Hazard Evaluations
(Springer, 2024) Selcuk, Levent; Selcuk, Azad Saglam
The correct estimation of seismic hazards is a touchstone of seismic risk assessments. However, there is no quantitative or standard methodology to include the impacts of geological (i.e., seismo-tectonic) features of active faults or fault zones, and current classification schemes are not useful in hazard evaluations. Therefore, an attempt has been made to develop a methodology that integrates seismo-tectonic parameters of active faults to better inform urban and regional planning decisions. Fault rating system (FRS) provides a comparative review of faults/fault zones using a rating-based approach. In this approach, seven seismo-tectonic parameters are used to classify the fault/fault zone. Each of the seven parameters is assigned a value corresponding to the seismo-tectonic characteristics. The sum of the seven seismo-tectonic parameters is the fault index (FI) value, which lies in the range 0-100. A total of 64 important faults/fault zones were statistically analyzed to determine the best correlations with FI and moment magnitude (Mw) and peak ground acceleration (PGA). It was found that the FI values provide strong correlations with maximum Mw and PGA. It is proposed urban and regional planners use FRS to ensure a consistent approach in characterizing key aspects of active faults in earthquake-prone regions and in estimating ground motion parameters.
Microzonation of the Plio-Quaternary Soils
(Springer Heidelberg, 2007) Selcuk, Levent; Ciftci, Yahya
Yuzuncu University (YYU) campus area is located on the eastern shore of Lake Van, within one of the active tectonic belts of Eastern Anatolia. The sediments accumulated in a lake formed when the Murat River was dammed by volcanoclastic deposits and hence include lacustrine, fluvial and sandy shore sediments. In order to delineate the liquefaction-prone soils, geological and geophysical data were assessed. On the basis of the Liquefaction Potential Index (I-L), three main geotechnical zones were identified in the study area and three microzones were delineated within the university campus to reflection the potential damage to structures.
A Nondestructive Testing Technique: Nail Penetration Test
(Amer Concrete inst, 2012) Selcuk, Levent; Gokce, H. Suleyman; Kayabali, Kamil; Simsek, Osman
This study presents a practical nondestructive testing (NDT) method: the nail penetration test (NPT). The major tools of the test technique are a gas nailer with 130 J (95.88 ft-lbf) power, concrete nails, and a gas nailer cell. The study covers three different limestone aggregate types. Six concrete mixtures were prepared from each aggregate type. Five nail shots were performed on each concrete mixture (or grade) and the average value was obtained. The average nail penetration depths were correlated with the compressive strength of concrete. Other NDT techniques, such as the Schmidt rebound hammer (SRH), ultrasonic pulse velocity (UPV), and Windsor probe (WP), were also applied to concrete samples. The measured compressive strength values were compared with those obtained from the empirical relationships using the data from the NPT, SRH, UPV, and WP. It was found that the reliability of the NPT to estimate the compressive strength of concrete is very high. The tool employed in the investigation covers a relatively wide range of compressive strength of concrete. This testing tool is proposed to estimate the compressive strength of in-place concrete.
Predicting California Bearing Ratio of Foundation Soil Using Ultrasonic Pulse Velocity
(Ice Publishing, 2019) Selcuk, Levent; Seker, Vedat
The California bearing ratio is a simple load-penetration test for determining the bearing capacity of soil being used as a foundation subgrade, subbase or base course. There are many empirical models to determine the ratio from soil index properties, but most of these are unsatisfactory. The scope of the investigation reported in this paper was to assess the reliability and accuracy of using ultrasonic pulse velocity for reliable estimates of bearing capacity. Ultrasonic pulse velocity is theoretically a much better indicator than other soil properties for evaluating bearing capacity as it is a function of density and elastic modulus and is strongly affected by material strength. A large-scale regression analysis was carried out using experimental data to evaluate the relationship between California bearing ratio and ultrasonic pulse velocity. Attenuation of ultrasonic waves was also investigated for measuring soil gradation, plasticity and compaction properties. It was found that the reliability and accuracy of ultrasonic pulse velocity in assessing the California bearing ratio indirectly seemed to be higher than those of traditional relationships between the ratio and these soil properties. These strong relationships are proposed for engineering projects requiring estimation of the California bearing ratio.
Prediction of Uniaxial Compressive Strength of Intact Rocks Using Ultrasonic Pulse Velocity and Rebound-Hammer Number
(Geological Soc Publ House, 2016) Selcuk, Levent; Nar, Azadi
Ultrasonic techniques are a simple, cost-effective, portable and non-destructive approach for evaluating the uniaxial compressive strength (UCS) of rocks. However, there are a number of factors affecting the ultrasonic pulse velocity (V-p) values. The main factors controlling the reliability of the method are surface irregularities of rock, micro-cracks and discontinuities, moisture content and porosity. To provide high prediction performances, data obtained from simple test methods are considered in combination to predict the mechanical properties of intact rocks. In this context, the use of both the V-p and Schmidt hammer rebound provides a better estimate of the UCS and minimizes the influence of the factors affecting the two techniques when they are used separately. The scope of this study is to assess the reliability and accuracy of the combined method in rock mechanics applications requiring the in situ determination of the UCS. The study material consists of various rock blocks of different strengths. The empirical relationships relating the V-p and rebound number (RN) were investigated using simple and multiple regression analysis. It was found that the combined method provides better estimates for UCS than V-p and RN separately. This method is proposed to indirectly determine the UCS of intact rocks.
Probabilistic Seismic Hazard Assessment for Lake Van Basin, Turkey
(Springer, 2010) Selcuk, Levent; Selcuk, Azad Saglam; Beyaz, Turgay
The seismic hazard for the Lake Van basin is computed using a probabilistic approach, along with the earthquake data from 1907 to present. The spatial distribution of seismic events between the longitudes of 41-45A degrees and the latitudes of 37.5-40A degrees, which encompasses the region, indicates distinct seismic zones. The positions of these zones are well aligned with the known tectonic features such as the Tutak-CaldA +/- ran fault zone, the A-zalp fault zone, the GevaAY fault zone, the Bitlis fault zone and KarlA +/- ova junction where the North Anatolian fault zone and East Anatolian fault zone meet. These faults are known to have generated major earthquakes which strongly affected cities and towns such as Van, MuAY, Bitlis, A-zalp, Muradiye, CaldA +/- ran, ErciAY, Adilcevaz, Ahlat, Tatvan, GevaAY and GurpA +/- nar. The recurrence intervals of M (s) a parts per thousand yen 4 earthquakes were evaluated in order to obtain the parameters of the Gutenberg-Richter measurements for seismic zones. More importantly, iso-acceleration maps of the basin were produced with a grid interval of 0.05 degrees. These maps are developed for 100- and 475- year return periods, utilizing the domestic attenuation relationships. A computer program called Sistehan II was utilized to generate these maps.
A Rational Method for Determining the Swelling Pressure of Expansive Soils: Paired Swell Test (ps-Test)
(Springer Heidelberg, 2022) Selcuk, Levent
Experimental investigations on the expansion behavior of clayey soils are of great importance to correctly understand the response of the soil-foundation. In this context, numerous statistical approaches and experimental techniques have been suggested to understand the swelling behavior of expansive soils, but most of these are unsatisfactory. The swelling characteristics of the soil are estimated by using the conventional consolidation apparatus, and the soil pressure is very sensitive to load increments during tests, especially in the zero swell tests. To provide reliable swelling pressure values for expansive soils, the existing methods are not based on refinements of load steps during the test. Ensuring the optimal swelling readings during the test is quite difficult unless the observations about the expansion response of specimens in different load steps have not been addressed in binary test pairs. The scope of the investigation is to assess the reliability and accuracy of oedometer testing methods and to propose a rational method based on a one-dimensional oedometer with a smaller degree of uncertainty for swelling pressure. A total of 252 remolded soil specimens were tested with commonly used oedometer methods to estimate the swelling pressure. The swelling pressure values were also measured using a specific design in which the swelling pressure under constant volume conditions is measured by an S-type load cell. The reliability and accuracy of the paired swell test (PS-test) in assessing the swelling pressure indirectly seemed to be higher than those of the conventional oedometer methods. The PS-test is proposed as a rational method for any engineering project that requires the prediction of swelling behavior of expansive soils.
A Strain Energy Framework for Evaluating Rock Mass Stability During Earthquakes
(Springer Heidelberg, 2025) Kayabali, Kamil; Habibzadeh, Farhad; Selcuk, Levent
This study examines the strain energy principle to address complex challenges in rock mechanics. Compared to conventional stress-strain assessments, the strain energy approach offers a more comprehensive perspective, representing a significant innovation in rock mechanics. The strain energy approach enhances reliability by considering energy accumulation and release alongside traditional strength analysis. Experimental studies indicate that the maximum energy stored and released during rock joint failure is comparable to earthquake energy capacities. This perspective introduces a novel approach for assessing rock mass stability during seismic events. The effectiveness of the energy-based approach is assessed using the hysteresis curves of rock joints under seismic loads. Experimental data reveal that the surface roughness of rock joints significantly influences the variation in strain energy with increasing normal stress. Moreover, evaluating the cyclic nature of earthquakes is essential for measuring strain energy, as the release of kinetic energy during an earthquake is inherently tied to its cyclic behavior. In this context, earthquake energy capacity is determined by analyzing the acceleration-time history of significant seismic events. Given that the strain energy from rock joint failure produces results comparable to earthquake energy capacities, the strain energy principle offers a more practical and realistic approach for assessing rock mass stability during earthquakes.
Van İli Kanalizasyon Boru Hatlarının Deprem Performansının Coğrafi Bilgi Sistemleri Kullanılarak Değerlendirilmesi
(2023) Kaplan, Ülker Cem; Özdamar, Osman Seyit; Erkalay, Gamze; Özvan, Ali; Tapan, Mücip; Selcuk, Levent
Van ili depremlerin sıklıkla gözlendiği şehirlerimizden birisidir. Son 100 yıl içerisinde Van ili ve çevresinde beşten fazla yıkıcı deprem meydana gelmiş, önemli can ve mal kayıpları yaşanmıştır. Hem 2011 yılında Van ilinde yaşanan depremlerde hem de 2023 yılında yaşadığımız Pazarcık-Elbistan merkez üslü depremlerde kanalizasyon sistemlerinden meydana gelen deformasyonun afetin boyutunu ve etkisini çok fazla arttırdığı görülmüştür. Bu çalışmanın amacı, Van merkez ilçelerinde yer alan kanalizasyon alt yapısındaki boruların deprem performansını coğrafi bilgi sistemlerinin kullanarak çok kriterli karar analizi ile değerlendirilmesidir. Çalışmada oluşturulan model üç ayrı faktörü içerir, bunlar; aktif fay hatlarına mesafe, boru tipleri ve zemin özellikleridir. Kanalizasyon boru sistemlerinin deprem duyarlık haritası, tüm tanımlı faktörlerin birbiri ile kıyaslanmasından oluşan karşılaştırma matrisi kullanılarak elde edilmiştir. Duyarlılık haritasına göre, fay hattına 4 km’den daha yakın mesafede konumlanmış kanalizasyon alt yapısında yer alan boruların, fay hatları tarafından üretilen depremlerde %45’nin yüksek veya çok yüksek hasar görebileceği şeklindedir. Özellikle Van Gölü’ne yakın kesimlerde yer alan İskele Mahallesi ve Edremit ilçe sınırlarının kuzey kesimlerinde yer alan kanalizasyon sistemleri yüksek risk altındadır. En önemlisi kentleşmenin en yoğun olduğu İpekyolu ilçesinin batı kesimleri, Tuşba ilçesinin güney kesimleri ile Edremit ilçesinin kuzeydoğu alanları ise yüksek risk altında olup, bu alanlar toplam kanalizasyon alt yapısının %39’unu oluşturmaktadır. Çalışmada uygulanan yöntem deprem esnasında gelişen deformasyonlara karşı güvenilir ve doğru bilgilerin elde edilmesine imkân tanımıştır. Bu bağlamda üretilen duyarlılık modeli ile hasar görebilirlik analizi, özellikle yüksek duyarlı alanlarda, alt yapı borularının depremden önce yapılacak olan uygulamaların çok daha düzenli ve planlı bir şekilde yürütülmesinde önemli rolleri olacaktır.