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Öğe Block masonry equation-based model updating of a masonry minaret and seismic performance evaluation(Springer Heidelberg, 2023) Onat, Onur; Toy, Ahmet Tugrul; Ozdemir, EnginThis paper investigates a masonry minaret's current condition and seismic performance, namely Alacakapi Mir-Alay Sah Ali Bey (The short form is Alacakapi Minaret). Two prayer halls surround the Alacakapi minaret. One of these prayer halls was severely damaged by the Sivrice-Elazig earthquake on January 24, 2020. The other prayer hall is moderately damaged and still waiting for restoration and reinforcing solutions. The severely damaged hall was demolished. Due to the demolished hall, boundary conditions and clear height changed. Two surfaces are considered to be fixed supports. One is the bottom side, and the other is the vertical side. To determine the current condition of the minaret, first, dynamic identification is conducted by five accelerometers. Then destructive and non-destructive tests were performed to determine material properties. After that, a solid model was generated, and model calibration was conducted. Eight different formulations were considered for the model calibration proposed in the literature, reflecting a homogenized material approach that includes brick-and-mortar units. Three different mortar strengths were considered to obtain the best material properties that demonstrate the actual situation of the minaret. Local damage is realized when comparing the finite element model and operational modal analysis results. Finally, six different earthquake records were selected to determine the seismic response of Alacakapi Minaret to determine vulnerable locations for retrofit solutions.Öğe Damage propagation and failure mechanism of single dome historical Masonry Mosque after February 6, 2023, Kahramanmaras,earthquake doublets (Mw = 7.7 and Mw = 7.6)(Elsevier Science Inc, 2024) Onat, Onur; Ozmen, Alper; Ozdemir, Engin; Sayin, ErkutMany historical masonry mosques and minarets, including Milky Minaret Mosque and Ulu Mosque, which are very close to Ak Minaret Mosque in Malatya, suffered severe damage and collapsed after the Kahramanmaras, , earthquake on February 6, 2023. Despite the settled loose soil properties and the presence of a small stream flow near the mosque, Ak Minaret Mosque, a historical masonry mosque with a single dome and square, remains operational even after the aforementioned earthquakes. Additionally, DEMA's strong ground motion station was out of service during both earthquakes. This situation raises questions about the mosque's ability to withstand the seismic load. The basic purpose of this paper is to investigate in detail the seismic performance, damage limits, the reason for unexpectedly less damage due to the earthquakes, the potential failure mode, and possible resisted earthquake loads of the historical Ak Minaret Mosque in Malatya, T & uuml;rkiye. To achieve this goal, first, dynamic identification was performed on the mosque one year prior to the aforementioned earthquakes. Next, the material properties were determined using both non-destructive and destructive testing methods. Following the dynamic identification, a numerical model was generated by 3-D solid elements, and this 3-D model was calibrated using the dynamic identification tests. The mosque underwent both nonlinear static and nonlinear dynamic analyses. Nine seismic records were selected for the nonlinear dynamic analysis. Five of them were national, including even Kahramanmaras, , earthquake records, and three of them were selected from an international database on the basis of fault characteristics and site classification. The analysis results indicate that Ak Minaret Mosque incurred less damage than expected during the Kahramanmaras, , earthquakes. This could be due to soil improvement prior to the construction of Ak Minaret Mosque in 1573. Moreover, the effective restoration increased stiffness and maintained the mosque's stability. Finally, the possible resisted PGA by the mosque was around 0.22 g.Öğe Determining point load strength loss from porosity, Schmidt hardness, and weight of some sedimentary rocks under freeze-thaw conditions(Springer, 2018) Sarici, Didem Eren; Ozdemir, EnginRocks are subjected to various atmospheric, climatic, and seasonal effects, and those effects can cause partial or complete deterioration. To understand the degree of deterioration of rocks, especially in cold regions, the influences of freeze-thaw cycles on physico-mechanical properties need to be investigated. This study assesses the influence of freeze-thaw cycles on some physical and mechanical properties of some rocks of sedimentary origin in Turkey. For this purpose, samples were subjected to 30 freeze-thaw cycles, and porosity, point load strength, Schmidt hardness, and weight loss were determined after every five cycles. The freeze-thaw cycle progression led to decreases in point load strength, Schmidt hardness, and weight and an increase in porosity of the specimens. The increase and decrease ratios were calculated at the end of every five freeze-thaw cycles, and the relationships were determined for estimated point load decrease ratios. At the end of 20 cycles, there was a strong relationship between point load strength loss and Schmidt hardness loss (R-2 = 0.903), which can be very useful for predetermination of point load strength decrease after freeze-thaw cycles without testing.Öğe Effects of acid-base solutions on some Turkish natural building stones: physico-mechanical and color changes(Springer Int Publ Ag, 2022) Ozdemir, Engin; Kantarci, Fatih; Eren Sarici, DidemNatural stones are exposed to various physical, chemical and environmental interactions during service life. It is quite important to determine physico-mechanical properties of natural stones for specific applications. This paper presents an experimental study conducted to explore effect of acid and sulfate shocks on some physico-mechanical properties and color of natural stones. For this purpose, five different building stones used as marble (Malatya Beige, Agri Onyx, Adiyaman Crystal Emperador, Diyarbakir Black Pearl, Elazig Rosso Levanto) were supplied from eastern region of Turkey. Point load strength, Schmidt hardness rebound, unit weight, porosity, water absorption and color measurements were conducted on provided natural stones. Additionally, mineralogical properties of natural stones were investigated with XRD and XRF analyses. Then, these natural stones were exposed to chemical shocks with 5% H2SO4 and Na2SO4 solutions for 0, 10, 20 and 30 cycles. Changes in Schmidt hardness, point load strength, porosity, dry weight and color after chemical shock cycles were investigated. Experimental results showed that Diyarbakir Black Pearl (DBP) and Malatya Beige natural stones might be used in aggressive H2SO4 and Na2SO4 environments for structural and ornamental purposes. After 30 cycles of H2SO4 and Na2SO4 shock, minimum decrease in point load values was obtained from DBP samples with 5.97% and 9.15%, respectively. Similarly, decrease in Schmidt harness values of DBP was minimum. Among natural stones exposed to H2SO4 and Na2SO4 shocks, AO sample that had the greatest strength loss was 17.36% and 9.68%, respectively.Öğe The effects of some environmental conditions on the mode I fracture toughness of rocks(Springer, 2024) Ozdemir, Engin; Sarici, Didem ErenFracture toughness is an important parameter in determining the fracture mechanism of rocks, concretes and other composites, and it is used in performing design and stability analyses. In this study, the aim was to determine the effects of different environmental conditions (dry, saturated, freezing, thermal shock and thermal aging) on fracture toughness and fracture energy values of rocks from three different origins: gabbro, recrystallized limestone and limestone. In the first stage, the physical, chemical, mechanical, mineralogical and petrographic properties of rocks were determined. The material properties of rocks were revealed by physico-mechanical tests, XRD, XRF and petrographic analysis. In the second stage, the rocks were aged by exposing them to pre-determined environmental conditions for a certain period of time and then, semi-circular bending strength tests were applied to the aged rocks. SEM images were taken to determine the effects of different environmental conditions on surface cracks. According to the experimental results, thermal shock, thermal ageing and water saturation conditions led to decreasing fracture toughness, while freezing conditions led to increasing fracture toughness. It was determined that thermal shock was the environmental condition that caused the most weakening. In freezing conditions, it was observed that physico-mechanical properties and fracture toughness values of rocks increased. It was seen that the fracture toughness values of the monomineralic structured samples were more affected by the environmental conditions than the multimineralic rocks.Öğe Effects of thermal shock and aging on natural stones: an experimental and statistical study(Springer, 2023) Ozdemir, Engin; Sarici, Didem ErenNatural stones are exposed to sudden and slow-developing thermal cycles, affecting their physico-mechanical and surface properties. In this study, changes in the physico-mechanical properties of natural stones in response to sudden (thermal shock) and slow-developing (thermal aging) thermal cycles were investigated on natural stone samples with various compositions (magmatic, sedimentary, metamorphic). Both the thermal shock and thermal aging cycles were simulated by first heating the specimens to 105 degrees C for 18 h. In case of the thermal shock cycles, the heating phase was followed by placing the samples in purred water for 6 h. To simulate the thermal aging cycles, specimens were allowed to cool at room temperature (23 degrees C) for 6 h. At the end of the cycles, a selection of physico-mechanical properties was evaluated and compared with the initial values. Results indicate that thermal treatments have a significant negative effect on the strength of the natural stone samples. Regression models were developed to estimate uniaxial compressive strength, point load strength, Brazilian tensile strength from non-destructive test parameters (Schmidt hardness, P wave velocity, porosity) of natural and treated samples. Results show that there are strong correlations between mechanical properties and non-destructive test parameters (R-2 > 0.96, MAPE values between 2 and 5%).Öğe Estimation of mode I fracture toughness of rocks exposed to different environmental conditions using simple and linear multiple regression(Springer, 2024) Ozdemir, Engin; Eren Sarici, DidemMode I fracture toughness (K & imath;c) is a critical parameter in rock mechanics that is essential for understanding how rocks behave under tensile loading and crucial for applications ranging from safety assessments to structural design in geotechnical engineering. This study comprehensively investigates the influence of various environmental conditions (dry, saturated, frozen, thermal shock and thermal aging) on the physico-mechanical properties and K & imath;c of rocks. The primary novelty of this study lies in its comprehensive modeling approach under diverse environmental conditions, providing a nuanced understanding of factors influencing rock fracture toughness. By extending analysis to less-studied conditions such as freezing and thermal shock cycles, the study enhances the predictive capacity of fracture toughness models in practical geotechnical applications. Physico-mechanical properties, including uniaxial compressive strength, point load strength, Brazilian tensile strength (BT), Schmidt hardness, and ultrasonic wave velocity were evaluated across different environmental scenarios. Simple and linear multiple regression models were developed using these properties to predict K & imath;c. Notably, BT emerged as a significant predictor in the simple regression analyzes. Ten linear multiple regression models were formulated using SPSS 20, combining mechanical tests (UCS, BT, PL) with non-destructive testing methods (Vp, Vs, SH), demonstrating robust predictive capabilities with R2 values exceeding 0.95. Performance metrics (mean absolute error, mean absolute percentage error, root mean square error) were used to verify the accuracy of the model.Öğe Estimation of Uniaxial Compressive Strength of Travertines Using Leeb Hardness(Pleiades Publishing Ltd, 2024) Ozdemir, Engin; Dolmaz, OsmanDensity, porosity, P-wave velocity and Leeb hardness were determined for travertine samples from different quarries in Turkey, and the relationship of these properties with uniaxial compressive strength values was evaluated. Exponential relationships were obtained between UCS and physical and mechanical properties of test samples. The strongest relationship was obtained between UCS and the Leeb hardness, at the correlation factor R-2: 0.91.Öğe Impact of restoration-based structural modifications on the seismic response of the historical Vaiz Sunullah Melik minaret during the 2023 Kahramanmaras, earthquakes(Elsevier Science Inc, 2026) Onat, Onur; Ay, Enes; Ozdemir, Engin; Toy, Ahmet TugrulThe current paper aims to present the seismic performance of the historical masonry Vaiz Sunullah Melik Minaret in Malatya during the February 6, 2023, Kahramanmaras, earthquakes. After the February 24, 2020, Elaz & imath;g-Sivrice earthquake, the studied minaret suffered slight damage and underwent restoration. The restoration had just been completed when the Kahramanmaras, earthquake struck the historical masonry minaret on February 6, 2023. Before the restoration, a small masjid was adjacent to the minaret and functioned together with it. However, before starting the restoration of the minaret, the masjid was demolished, and a new masjid was constructed 75 cm away from the minaret. Interestingly, this intervention revealed unexpected rotation at higher frequency at the pulpit of the minaret. Before the Kahramanmaras, earthquakes, dynamic identification tests were carried out to capture the pulpit rotation, and material characterization was completed. A numerical model was developed to represent the current condition of the minaret, and the material properties were calibrated to obtain a digital twin. Subsequently, a second numerical model was developed to represent the support condition prior to the restoration. Eleven national and international earthquake records (From 0.15 g to 0.58 g) were used for nonlinear time-history analyses to evaluate differences in seismic performance under the two support cases. A total of twenty-two nonlinear dynamic time-history analyses were conducted. The nonlinear analysis results indicate that constructing the new masjid as a detached structure increased torsional demand at the pulpit and was associated with observable damage during the Kahramanmaras, earthquakes, particularly given the relatively low material properties at the pulpit level. This response contributed to widening of existing cracks, deterioration of pulpit integrity, and the development of new cracking along the shaft.Öğe Investigation of Some Property Changes of Light-Colored Turkish Natural Stones after High-Temperature Treatments(Mdpi, 2022) Ozdemir, EnginNatural stones are a widely used construction material for both structural and decorative purposes. It is a material used for many floors and cladding due to its special beauty and quite aesthetic appearance. However, natural stones are exposed to different temperatures due to natural, urban or industrial activities and they lose their physico-mechanical properties. It is known that high temperatures and fire cause degradation of construction and building stones. There are many studies investigating the effect of high temperatures on physical and mechanical properties of natural stones, while there are very limited studies on color and gloss. In this study, the changing physical and mechanical properties, color and gloss of different light-colored polished natural stones exposed to room temperature up to 1000 degrees C in the oven were investigated. For this purpose, natural stones were gradually exposed to 200, 400, 600, 800 and 1000 degrees C, starting from room temperature. After exposure to different temperatures, water absorption, porosity, Schmidt hammer hardness, point load strength, color and gloss were measured and compared to reference samples (at room temperature). However, all samples were decayed at 1000 degrees C, changes at this temperature value could not be determined. The results obtained at other temperature values were evaluated separately for each parameter. While the change in physico-mechanical properties of all samples up to 400 degrees C was limited, a dramatic change was observed with increasing temperature. In all samples, point load strength losses were observed due to an increase in porosity and water absorption. In addition, all samples darkened at 400 degrees C, while the whiteness value (L*) of samples increased at 800 degrees C. Gloss values gradually decreased due to the increase in temperature.Öğe Modeling uniaxial compressive strength of some rocks from turkey using soft computing techniques(Elsevier Sci Ltd, 2021) Gul, Enes; Ozdemir, Engin; Sarici, Didem ErenUniaxial compressive strength (UCS) is substantially used mechanical parameters to observe and classification of rocks, but this test is subsersive, taking a long time and required well equipped laboratory conditions and properly prepared samples. Therefore it is important to estimate this parameter from other physico-mechanical rock parameters that are nondestructive, easy to prepare samples and required less time. Machine learning methods which are among these methods and increase their importance and validty are Multilayer Perceptron Neural Network (MLPNN), M5 Model Tree (M5MT), Extreme Learning Machine (ELM) methods. In this study, Brazilian tensile strength, ultrasonic P-wave velocity, shore hardness tests of different rock types (Basalt, limestone, dolostone) were performed. The results were used for estimating UCS using MLPNN, M5MT, ELM methods. The validation of models were checked root mean squared error (RMSE), mean absolute error (MAE), variance account for (VAF) and coefficient of determination (R-2) and a10-index. Weights and bias values for MLPNN and ELM approaches and the tree structure for the M5MT method are presented. The result indicated MLPNN model outperforms the other models. Based on the result of predictive models with RMSE, MAE, VAF and R-2 equal to RMSE: 1.3421, MAE: 0.7985, VAF: 99.7409, R-2: 0.9982%.Öğe A New Predictive Model for Uniaxial Compressive Strength of Rock Using Machine Learning Method: Artificial Intelligence-Based Age-Layered Population Structure Genetic Programming (ALPS-GP)(Springer Heidelberg, 2022) Ozdemir, EnginUniaxial compressive strength (UCS) of rocks is the most commonly used parameter in geo-engineering application. However, this parameter is hard for measurement due to a time consuming and requires expensive equipment. Therefore, obtaining this value indirectly using non-destructive testing methods has been a frequently preferred method for a long time. In order to obtain multiple regression models, input parameters need many assumptions. Thus, the estimation of the mechanical properties of rocks using by machine learning methods has been investigated. In this study, UCS values of rocks were estimated by reformulating with artificial intelligence-based age-layered population structure genetic programming (ALPS-GP) which is one of machine learning methods. Artificial neural network (ANN) and ALPS-GP models were performed to predict UCS from porosity, Schmidt hammer hardness and ultrasonic wave velocity test methods. For this purpose, the mentioned three tests (porosity, Schmidt hammer hardness and P-wave velocity) were carried out on ten different stones from Turkey. ANN was performed to evaluate this new technique. Reliability of UCS values determined by models was checked with mean absolute error (MAE), coefficient of determination (R-2), root mean square error (RMSE) and variance account for (VAF) values. These values were calculated as 1.64, 0.98, 2.11 and 99.81 for ANN, and 2.11, 0.98, 2.50 and 97.86 for ALPS-GP, respectively. It was observed that both methods used were quite successful in UCS estimation. The most important advantage of the ALPS-GP model is providing an equation for UCS estimation. In the light of the obtained findings, it has been revealed that this equation derived from ALPS-GP can be used in UCS estimation processes of similar rock types (limestone, dolomite and onyx).Öğe Performance evaluation and damage assessment of historical Yusuf Ziya Pasha Mosque after February 6, 2023 Kahramanmaras earthquakes(Elsevier Science Inc, 2023) Onat, Onur; Deniz, Faruk; Ozmen, Alper; Ozdemir, Engin; Sayin, ErkutHistorical masonry heritages are severely affected by the February 6, 2023, Kahramanmaras, earthquakes. The recorded earthquake peak ground accelerations (PGA) are 2.05 g and 0.67 g for Pazarcik and Elbistan earth-quakes at the epicenter, respectively. However, there is not any recorded PGA data related to Kahramanmaras, earthquakes in Malatya. At this point, the current study aims to propose a methodology to estimate the possible resisted load of historical Yusuf Pasha Mosque in Malatya and possible PGA for Malatya by assessing the per-formance located in Malatya city center, which is far from the epicenter of Pazarcik earthquake, which is 162 km, and Elbistan earthquake, which is 100 km, using propagated cracks. After these earthquakes, local damages were registered at the Yusuf Ziya Pasha Mosque. The main prayer hall of the mosque and a tomb were constructed in 1792. Three types of materials were used for the mosque: riyolit tuff, sandy tuff for walls, and timber for the roof. The dimensions of the main hall of the mosque are 17.50 m x 12.53 m. Additionally, there is a small tomb located adjacent to the mosque with dimensions of 7.61 m by 4.46 m. First of all, dynamic identification is conducted, and then a numerical model is generated. Material properties were calculated using non-destructive testing methods. The mosque and the tomb are modeled together. The numerical model is calibrated on the basis of the extracted dynamic parameters. Then, nonlinear time history analyses were performed on the model using eight earthquake records. Three of the used seismic records were international, namely the 1995 Kobe, 1986 Chalfant Valley, and 2010 New Zelland Darfield earthquakes. In addition, five national earthquake records are used for the nonlinear dynamic analyses, namely the 2003 Bingo center dot l, 2011 Van-Ercis,, 2020 Elazig-Sivrice, 2023 Kahramanmaras, Pazarcik, and Elbistan earthquakes. Related graphs were tabulated, and crack propagations of the numerical model were compared to damaged mosques.Öğe Uniaxial compressive strength prediction in rocks: a comprehensive review from empirical equations to AI methods(Springer Int Publ Ag, 2026) Ozdemir, EnginUniaxial compressive strength (UCS) is one of the most fundamental parameters in rock mechanics, widely used in the design and stability assessment of geotechnical and mining structures. However, its direct determination requires high-quality samples, sophisticated laboratory facilities, and significant time and cost, which often limit its applicability in practice. As a result, a broad spectrum of indirect estimation techniques has been developed, ranging from simple empirical correlations to advanced artificial intelligence (AI) models. This review provides a comprehensive synthesis of the methods employed in UCS estimation, with a particular focus on both conventional index tests and machine learning approaches. Traditional methods such as the Schmidt rebound hammer (SRH), ultrasonic pulse velocity (UPV), point load test (PLT), and Brazilian tensile strength (BTS) have demonstrated considerable utility, though their predictive accuracy is highly dependent on lithology, rock anisotropy, and site-specific conditions. On the other hand, AI-based techniques, including artificial neural networks (ANN), adaptive neuro-fuzzy inference systems (ANFIS), and optimization-enhanced hybrid models, have achieved superior predictive performance by capturing nonlinear and multivariate relationships, often yielding coefficients of determination (R2) above 0.95. Despite their promise, AI methods require large and representative datasets, and issues of model interpretability and overfitting remain challenges. The comparison highlights that no single approach is universally applicable; rather, the integration of empirical knowledge with computational intelligence appears to be the most effective strategy. The study concludes that future research should prioritize the development of hybrid models and standardized open-access databases to enhance the accuracy, robustness, and practical applicability of UCS prediction in diverse geological settings.Öğe Utilization of granite waste as alternative abrasive material in marble grinding processes(Elsevier Sci Ltd, 2018) Sarici, Didem Eren; Ozdemir, EnginWastes formed during the production and processing of marble and granite cause problems for the leading countries in natural stone production because they result in environmental pollution, negative conditions for health and cause economic losses. Decreasing the formation of waste materials and studies on their reusability are important to provide environmental and economic benefits. The main purpose of this study is to determine the reusability of the waste material formed during granite production as conventional artificial abrasive in the marble abrasion process. Accordingly, three different marble samples commercially available in different areas of Turkey were studied. Bohme abrasion test was carried out with Al2O3 and granite waste, which are used as common abrasives in marble abrasion operations. The waste of granite was classified in three different grain sizes after processing it with solid-cutting, crushing-grinding and screening operations and then used in Bohme abrasion test run. The performance of abrasion process was evaluated as the decrease in the surface roughness of marble samples and the increase in the surface gloss. As a result of tests, the performance of granite wastes and Al2O3 abrasives were compared. Test results showed that granite wastes caused a relative decrease in marble surface roughness and an increase in gloss especially in high CaCO3 and low MgCO3 containing soft rocks such as travertine. (C) 2018 Elsevier Ltd. All rights reserved.
