Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Kamiloglu, Hakan Alper(3)
- Gökçe, H. S.(2)
- Sadoglu, Erol(2)
- Aksan, U.(1)
- Aksan, Umut(1)
- Altunisik, Ahmet Can(1)
- Andiç-Çakir, Ozge(1)
- Birinci, Ahmet(1)
- Drosopoulos, Georgios(1)
- Ergün, Mustafa(1)
- Fistikoglu, Okan(1)
- Gökçe, H. Suleyman(1)
- Günaydin, Murat(1)
- Kul, Sinan(1)
- Köseoglu, K.(1)
- Maravelakis, Emmanuel(1)
- Motsa, Siphesihle Mpho(1)
- Nehdi, M. L.(1)
- Nuhoglu, Alper(1)
- Okkan, Umut(1)
- Okur, Fatih Yesevi(1)
- Ramyar, K.(1)
- Stavroulaki, Maria(1)
- Stavroulakis, Georgios(1)
- Sunca, Fezayil(1)
- Tapkin, Serkan(1)
- Tercan, Emre(1)
- Tuyan, M.(1)
- Yaylaci, Murat(1)
- Öner, Erdal(1)
Yayınlar
- MakaleAçık Erişim2023Scopus SJRQ1New RSM-FEM-Based Active Lateral Earth Thrust Coefficient Determination Method for Inverted T-Type Cantilever Retaining Walls Supporting Narrow Granular Backfill
Kamiloglu, Hakan Alper
This study was aimed to (1) investigate the failure surface mechanism occurring behind the wall supporting narrow backfill with experimental and numerical approaches; (2) determine the effect of internal friction angle (phi), friction (delta), heel length (beta), foundation thickness (alpha), backfill inclination (psi), and backfill width (theta) parameters on lateral earth thrust coefficients; and (3) derive finite-element analysis (FEM)-response surface method (RSM)-based lateral earth thrust coefficient equations for inverted T-type retaining walls supporting narrow backfill. The study was performed for granular backfill. A small-scale test was performed to investigate the failure surface mechanism in the narrow granular backfill. The particle image velocimetry method was employed to determine failure surface patterns for various heel lengths and backfill widths. Finite-element (FE) analyses were also performed to verify the experimental results. From the analyses, it was seen that two characteristic soil blocks formed behind the horizontally translated wall. Due to these soil blocks, the wall was divided into three characteristic regions. Lateral active earth thrust coefficients were derived for the regions. RSM was employed to derive FE-based lateral earth thrust coefficient estimation equations for each region. In this context, three design matrices were created, comprising 76 runs. In the design, parameters phi, delta, beta, alpha, psi, and theta were used as independent variables. A total of 76 FE analyses were performed for various parameter combinations. The results of the FE analyses were used as a response. From the statistical analyses, lateral active earth thrust estimation equations for narrow backfill were derived. The suggested equations were compared with the results of experimental, numerical, and analytical studies, and it was seen that the method gives reliable results. The effects of independent variables and their interactions on lateral earth pressure coefficients were examined.
AtıfWoS3OpenAlex3
İncele - MakaleYalnız künye2022Scopus SJRQ1Nondestructive Experimental Measurement, Model Updating, and Fatigue Life Assessment of carsamba Suspension Bridge
Günaydin, Murat; Sunca, Fezayil; Altunisik, Ahmet Can; Ergün, Mustafa; Okur, Fatih Yesevi
This paper includes the structural condition assessment of a 164-m suspension bridge in accordance with numerical and experimental methods. A finite-element model was developed using SAP2000 software so that the assessment of the bridge could be calculated numerically. The operational modal analysis method was also used to obtain experimental dynamic characteristics. In this context: (i) numerical dynamic characteristics of the bridge were obtained and compared with the experimental dynamic characteristics, (ii) a model updating procedure was carried out to minimize the differences between the numerical and experimental natural frequencies, (iii) static and dynamic analyses of the bridge were carried out by using the initial and updated finite-element models, (iv) fatigue life assessment of the bridge was investigated, and (v) the utility of the bridge for pedestrians and vehicles was checked according to various regulations. The results showed that updating the finite-element model had a significant role to play in the static and dynamic behavior of the bridge. The results also demonstrated that the bridge was designed to be extremely safe against static, dynamic, and fatigue loads. Finally, it was concluded that the bridge investigated behaves as a girder bridge rather than a suspension bridge.
AtıfWoS17OpenAlex18İncele - MakaleAçık Erişim2022Scopus SJRQ1Structural Investigation of Masonry Arch Bridges Using Various Nonlinear Finite-Element Models
Tapkin, Serkan; Tercan, Emre; Motsa, Siphesihle Mpho; Drosopoulos, Georgios; Stavroulaki, Maria; Maravelakis, Emmanuel; Stavroulakis, Georgios
This article presents an investigation of the structural behavior of a masonry arch bridge in Turkey. An analytical study has been conducted to provide the geometry of the structure, using laser scanning. A point cloud describing the geometry was obtained and properly transformed into a format that is appropriate for structural analysis software (CAE). Then, nonlinear finite-element models were developed to simulate structural responses of the bridge. The goal of the article is to highlight the influence of both continuum and discrete approaches and related constitutive laws on the responses of the bridge. Thus, continuum damage laws and a discrete model consisting of unilateral contact-friction interfaces were developed. Different load cases were tested and a comparison between the results obtained from the different approaches was considered. The failure mechanisms and the ultimate strengths were derived, and core points of the models were highlighted. The output of this work shows how the different failure models predict the behavior of the masonry arches. It also shows that the three-hinge mechanism, which has been depicted in classical studies for single-span arch masonry bridges under a horizontal settlement of supports, may also be obtained for multiarch bridges. Similarly, downward, vertical settlement of supports may result in the development of two hinges, as in single-span arches. Finally, the beneficial influence of the backfill in limiting the failure in the arch is addressed.
AtıfWoS18OpenAlex21İncele - MakaleYalnız künye2021Scopus SJRQ1Enhancing Burnability Characteristics of Low-Temperature Burnt-Cement Clinker by Recycling Phosphogypsum Wastes
Aksan, U.; Köseoglu, K.; Gökçe, H. S.
In the present study, the effect of phosphogypsum, a byproduct from the phosphoric acid production industry, on the clinkerization process was researched in order to improve the burnability of clinkers at lower burning temperatures. Raw meal samples containing phosphogypsum at 0%, 1%, 3%, and 5% by weight were burned at 1,350 degrees C, 1,400 degrees C, 1,450 degrees C, and 1,500 degrees C. The introduction of phosphogypsum reduced the presence of unbounded (free) CaO relatively up to 43%. Thus, the mineralization effect of phosphogypsum promotes lower burning temperatures. The free CaO content of the 5% phosphogypsum containing clinker decreased to 0.94% at 1,400 degrees C after 120 min of burning time. The free CaO content was found to be almost identical (0.75%) to that of industrial clinker burned in a rotary kiln at 1,500 degrees C. Due to the low free CaO content (<1%) and the burnability index (73), the recycling of phosphogypsum wastes was found to be suitable for the production of eco-efficient clinkers. The reduced energy consumption and energy-related CO2 emissions in such modified clinkers can contribute to the economic and ecological goals of the cement industry. (C) 2021 American Society of Civil Engineers.
AtıfWoS2OpenAlex3İncele - MakaleAçık Erişim2020Scopus SJRQ2Removal Kinetics of Olive-Mill Wastewater in a Batch-Operated Aerobic Bioreactor
Kul, Sinan; Nuhoglu, Alper
This study involves the removal of the olive-mill wastewater (OMW), which is a significant pollutant, in a batch reactor under aerobic conditions by mixed cultures. It also includes comparison of different substrate inhibition models, calculation of kinetic parameters, and testing the merit of the chosen mathematical model with respect to OMW concentration and changes with time. Average initial microorganism concentration (X0) in the batch reactor was 100 +/- 15 mg L-1. During the study the treatment of OMW with initial chemical oxygen demand (S0) concentration between 10 and 1,000 mg COD L-1 was investigated. Maximum specific growth rate (mu max) was reached with 130 mg COD L-1 initial concentration and 3 h experimental duration produced 57.17% chemical oxygen demand (COD) removal efficiency. Other experiments with increasing initial concentration increased COD removal duration, with 927 mg COD L-1 initial concentration regressing to 8.88% removal efficiency after 3 h. The biokinetic equations of Aiba, Haldane, Tseng, and Yano and Koga were chosen to relate S0 concentration to specific growth rate (mu) and the biokinetic parameters in these equations were calculated. The most appropriate biokinetic equation was the Haldane model in terms of R2 value and the Haldane equation parameters 0.43 h-1, 45.34 mg L-1, and 207.97 mg L-1 were calculated for mu max, half-saturation constant (Ks) and inhibition constant (Ki), respectively. Also, a mathematical biokinetic model including the Haldane equation was used to test the OMW removal performance and it was seen that the chosen model was well able to reflect system behavior. After the calibration of mu max, the most-sensitive parameter of the Haldane model, to 0.22 h-1, the model gave a better fit for all tested conditions.
AtıfWoS2OpenAlex7İncele - MakaleAçık Erişim2020Scopus SJRQ1Development of Eco-Efficient Fly Ash-Based Alkali-Activated and Geopolymer Composites with Reduced Alkaline Activator Dosage
Gökçe, H. S.; Tuyan, M.; Ramyar, K.; Nehdi, M. L.
The eco-efficiency and economy of geopolymer composites largely depend on their alkaline activator dosage. In this study, the effect of applying a pre-setting pressure and variation of the aggregate-to-fly ash ratio on the alkaline solution dosage and mechanical strength of fly ash-based geopolymer composites was explored. It is shown that through control of the aggregate-to-ash ratio and application of pre-setting pressure, compressive strength could be increased by 102% and 86% for Class F fly ash-based geopolymer and alkali-activated Class C fly ash-based mixture, respectively. The total alkaline solution consumption could be reduced from 718 to 188 kg/m(3) and from 769 to 262 kg/m3 for Class F fly ash-based geopolymer and alkali-activated Class C fly ash-based mixture, respectively. The proposed method reduced the alkaline solution consumption per compressive strength (6.2 kg.m(-3).MPa-1) by up to 85% compared to that of the reference manually consolidated control geopolymer. The findings demonstrate that fly ash-based geopolymers could be made more sustainable and eco-efficient through tailored production techniques. (C) 2019 American Society of Civil Engineers.
AtıfWoS23OpenAlex30İncele - MakaleAçık Erişim2019Scopus SJRQ1Experimental and Theoretical Investigation of Short- and Long-Heel Cases of Cantilever Retaining Walls in Active State
Kamiloglu, Hakan Alper; Sadoglu, Erol
Failure surfaces are very effective in active lateral earth thrusts acting on cantilever retaining walls. The intersection of failure surface and cantilever retaining wall should be taken into account for determination of active earth thrust. Calculations of lateral earth thrusts vary for two different cases, short heel or long heel, based on the intersection of cantilever wall and failure surface. However, the common methods are devoted to a particular case (long heel or short heel). This study intended to suggest a new lateral earth thrust method that is applicable to cantilever walls with a short heel or long heel using the limit-equilibrium approach. For this purpose, an earth thrust-maximization algorithm was prepared and coded by using Matlab Environment to determine active earth thrust coefficients and failure surface inclination angles occurring behind a cantilever wall in an active case. Also, the failure surfaces occurring behind model cantilever walls and the failure cases were examined experimentally by using particle image velocimetry (PIV) analysis. Consequently, long-heel and short-heel cases and the effective parameters on the cases were investigated analytically and experimentally. (C) 2019 American Society of Civil Engineers.
AtıfWoS23OpenAlex24İncele - MakaleYalnız künye2019Scopus SJRQ1Assessment of Alternative Segregation Test Methods for Self-Consolidating Heavyweight Concrete
Gökçe, H. Suleyman; Aksan, Umut; Andiç-Çakir, Ozge
This investigation is focused on the use of alternative segregation test methods on high-performance self-consolidating heavyweight concrete. Many segregation test methods have been developed by researchers up to now; however, the disadvantages of these methods, such as being time-consuming, the requirement of excessive labor, and the lack of precision, cannot ensure their worldwide prevalence. In the study, the segregation limitations stated in various test methods, that is, the column test, density variation method, and 3-compartment sieve test, were evaluated on self-consolidating heavyweight concrete produced with barite aggregate. For this purpose, in total, eight self-consolidating heavyweight concrete mixtures designed in two water/binder ratios were prepared by replacing viscosity modifier, silica fume, and fly ash with ordinary Portland cement in different amounts. The mixtures were constituted in satisfactory segregation grades, allowing researchers to evaluate the relationship between those methods. The segregation coefficient limits of the column test, density variation method, and 3-compartment sieve test are recommended as 7%, 1%, and 6.3% for the self-consolidating heavyweight concrete mixtures tested in the study.
AtıfWoS5OpenAlex7İncele - MakaleYalnız künye2017Scopus SJRQ1Active Earth Thrust Theory for Horizontal Granular Backfill on a Cantilever Wall with a Short Heel
Kamiloglu, Hakan Alper; Sadoglu, Erol
Cantilever retaining walls are earth-retaining structures commonly used in construction. Conventional methods used to determine the active earth thrust acting on a wall often neglect friction between the soil and wall. This study presents an analytical solution for determining the active earth thrusts acting on a cantilever retaining wall with a short heel and a shear key that supports granular backfill. Three different earth thrusts were considered to be acting on three different parts of the rear face of the wall; the thrusts were derived using the limit equilibrium method. The active earth thrust formulas were also simplified in terms of earth thrust coefficients, unit weight, and wall height. An algorithm was developed to obtain earth thrust coefficients depending on various wall dimensions and internal friction angles and to prepare graphs representing earth thrust coefficients and failure surface angles. The effects of wall dimensions and internal friction angles on the earth thrusts and failure surface angles were determined. Finally, the proposed method of determining earth thrust coefficients was compared with other approaches.
AtıfWoS21OpenAlex20İncele - MakaleAçık Erişim2014Scopus SJRQ1Comparison between Analytical and ANSYS Calculations for a Receding Contact Problem
Yaylaci, Murat; Öner, Erdal; Birinci, Ahmet
This paper considers a receding contact problem for two elastic layers (with different elastic constants and heights) supported by two elastic quarter planes. The lower layer is supported by two elastic quarter planes, and the upper elastic layer is subjected to a symmetrical distributed load whose length is 2a on its top surface. It is assumed that contact between all surfaces is frictionless, and the effect of gravity force is neglected. First, the problem is formulated and solved using the theory of elasticity and integral transform technique. Using the integral transform technique and boundary conditions of the problem, the problem is reduced to a system of singular integral equations in which contact pressures and contact areas are unknown. The system of singular integral equations is solved numerically by using the Gauss-Jacobi integration formulation. Second, the receding contact problem has been developed based on the FEM ANSYS software. Two-dimensional analysis of the problem is carried out. The ANSYS and analytical results for the contact pressures, contact areas, and normal stresses (sigma(x) and sigma(y)) along the axis of symmetry are given for various dimensionless quantities. The ANSYS results are verified by comparison with analytical results. (C) 2014 American Society of Civil Engineers.
AtıfWoS50OpenAlex35İncele - MakaleYalnız künye2011Scopus SJRQ2Statistical Downscaling of Monthly Precipitation Using NCEP/NCAR Reanalysis Data for Tahtali River Basin in Turkey
Fistikoglu, Okan; Okkan, Umut
Statistical downscaling methods describe a statistical relationship between large-scale atmospheric variables such as temperature, humidity, precipitation, etc., and local-scale meteorological variables like precipitation. This study examines the potential predictor variables selected from the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) reanalysis data set for downscaling monthly precipitation in Tahtali watershed in Turkey. An approach based on the assessment of all possible regression types was used to select the predictors among the NCEP reanalysis data set, and artificial neural network (ANN)-based downscaling models were designed separately for each station in the basin. The results of the study showed that precipitation, surface and sea level pressures, air temperatures at surface, 850-, 500-, and 200-hPa pressure levels, and geopotential heights at 850- and 200-hPa pressure levels are the most explanatory NCEP/NCAR parameters for the study area. It was concluded that ANN-based downscaling models can be implemented to downscale coarse-scale atmospheric parameters to monthly precipitation at station scale by using the above parameters as inputs in the study area.
AtıfWoS65OpenAlex86İncele - DergiJOURNAL OF HYDROLOGIC ENGINEERING
- DergiJOURNAL OF ENVIRONMENTAL ENGINEERING
- DergiINTERNATIONAL JOURNAL OF GEOMECHANICS
- DergiJOURNAL OF ENGINEERING MECHANICS
- DergiJOURNAL OF BRIDGE ENGINEERING
- DergiJOURNAL OF MATERIALS IN CIVIL ENGINEERING