Browsing by Author "Kocaman, Irfan"

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Assessment of Seismic Behavior of Historical Masonry Cupolas: Case of Emir Saltuk Cupola
(Elsevier, 2024) Kocaman, Irfan; Gedik, Yusuf; Okuyucu, Dilek
The protection of historical masonry structures against earthquakes requires a comprehensive understanding of their nonlinear behavior; including damage and collapse mechanisms. Throughout history and in present times, these structures have undergone multiple strengthening interventions to enhance their seismic resilience. In this context, the utilization of nonlinear analysis on 3D finite element models has become a common and reliable approach. This article focuses on the seismic performance of historical Emir Saltuk Cupola of Erzurum city which is recognized as a cultural asset by the Ministry of Tourism and Culture of the Republic of Turkiye. Emir Saltuk Cupola is a rare work built in the 12th century as a monumental grave for the founder of Saltuklu Government. The study specifically examines the impact of a reinforced concrete pulley and dome, previously added to the cupola for the purposes of seismic strengthening, on its seismic behavior, force-displacement capacity, and collapse mechanism. Determining the seismic behavior of the structure is aimed to create an important reference for cupola structures, which are frequently encountered in the Turkish-Islamic geography. Notably, this study marks the first instance where advanced numerical simulation methods have been employed to analyses the cupola. Additionally, no prior research has been conducted to assess the propagation of damage and collapse mechanisms within this type of structure. Finite element model of the structure was developed considering the architectural characteristics of the cupola. The model was calibrated based on the findings of operational modal analysis. Nonlinear dynamic analyses were performed using ground motion records from significant earthquakes, including the 1992 Erzincan, 1995 Kobe and 2023 Kahramanmaras, earthquakes, to study the seismic behavior and collapse mechanisms of the cupola. The study evaluated the reinforced concrete pulley and dome in terms of maximum principal strains, maximum displacements, crack distributions, and failure mechanisms of the cupola. The reinforced concrete elements added to the structure in previous years, while assisting in a significant increase in strength capacity, did not contribute significantly to displacement capacity of the masonry. Additionally, it has been determined that under strong ground motions, these elements completely alter the collapse mechanism of the structure, leading to damage in the reinforced concrete elements and thus helping to prevent complete collapse. The findings highlight the substantial impact that strengthening interventions may be altering the seismic behavior of historical structures. Overall, this research contributes to our understanding of the seismic performance of historical masonry cupolas and emphasizes the importance of accurately assessing their behavior through advanced numerical simulations which are supported by in-situ experimentation.
Bond-Slip Response of TRM-Concrete Systems with Chemically Embedded Epoxy-Anchors
(Pergamon-Elsevier Science Ltd, 2025) Mercimek, Omer; Yunculer, Murat; Caliskan, Ozlem; Kocaman, Irfan; Anil, Ozgur
This study investigates the bond-slip behaviour between Textile Reinforced Mortar (TRM) systems and concrete substrates through an extensive experimental and analytical approach. A total of 48 concrete block specimens were tested using a custom-designed direct pull-out test setup, where TRM strips were bonded to the top surface of concrete blocks and subjected to axial tensile loading. Key experimental parameters included concrete compressive strength (C15 and C30), TRM strip width (50 mm and 100 mm), bonded length (150 mm, 300 mm, 450 mm), and various configurations of fan type anchor systems, each comprising CFRP fan-anchors. The results demonstrated that increasing the strip width led to an average increase of approximately 68 % in maximum load capacity and 96 % in energy dissipation. Specimens with higher-strength concrete (C30) exhibited an average of 35 % greater bond capacity and 62 % higher energy absorption compared to those with lower-strength concrete (C15). Furthermore, the use of mechanical anchors resulted in average gains of 81 % in load capacity and nearly 165 % in energy dissipation relative to unanchored specimens. Based on the experimental findings, multivariate regression models were developed to estimate the key interface parameters required for cohesive zone modelling. The study provides a comprehensive understanding of the factors affecting the TRMconcrete bond and delivers valuable insight for the structural strengthening design of reinforced concrete elements.
Collapse Mechanism of Historical Masonry Mosques Under Strong Ground Motions
(Pergamon-Elsevier Science Ltd, 2023) Kocaman, Irfan; Kazaz, Ilker
The protection of historical masonry mosques against earthquakes can be achieved by an accurate assessment of nonlinear behavior, such as heavy damage and collapse. To this end, nonlinear analysis of 3D finite element models of structures is a common and reliable approach. This article examines the seismic performance of four historical mosques, which are defined as cultural assets by the Ministry of Tourism and Culture of the Republic of Turkey, under the influence of earthquake ground motion. Three of these mosques have not been studied before using any advanced numerical simulation method. In addition, no studies have been conducted to determine the damage propagation and collapse mechanisms of these mosques. Detailed finite element models were developed by defining the architectural features of mosques. In order to obtain the seismic behavior and collapse mechanisms of the mosques, nonlinear dynamic analyses were performed using the ground motion records from 1992 Erzincan, 1992 Cape Mendocino and 1995 Kobe earthquakes. An evaluation has been made for mosques in terms of mode shapes, maximum principal strains, maximum displacements, damage distributions and failure mechanisms. It has been determined that the crack distribution and damage mechanism can be generalized in historical masonry domed mosques with square plan.
Collapse Mechanism of Narthex Part of Historical Masonry Mosques
(Pergamon-Elsevier Science Ltd, 2023) Kocaman, Irfan; Gurbuz, Muhammed
Historical mosques are important cultural heritages that should be confidently transferred to the future. These structures are damaged due to earthquakes. The minarets, domes and load-carrying walls of historical mosques are the most damaged and studied in the literature. Field observations made after the earthquakes show that; the narthex part of the historical mosques is also very seismic sensitive. However, there is no study in the literature about the collapse mechanisms of these structures/parts. In this study, 3 narthex places with different architectural features were considered. By creating a finite element model of the narthexes, dynamic analyses were carried out under the earthquake records of 1999 Duzce (Bolu) (Mw = 7.1), 2011 Van (Mw = 7.0), 2020 Elazig (Sivrice) (Mw = 6.8). An evaluation has been done to assess mode shapes, maximum strains, displacements, damage distributions, and failure mechanisms of the narthex parts. As a result of dynamic analyses, the general collapse mechanism of each narthex was revealed. As a result of all analyses, it has been seen that the most seismically sensitive areas of the narthex are stone columns.
A Data-Driven Machine Learning Approach for Predicting Axial Load Capacity in Steel Storage Rack Columns
(Elsevier, 2025) Mammadli, Bakhtiyar; Yazici, Casim; Gurbuz, Muhammed; Kocaman, Irfan; Dominguez-Gutierrez, F. Javier; Ozkal, Fatih Mehmet
In this study, we present a machine learning (ML) framework to predict the axial load-bearing capacity, (kN), of cold-formed steel structural members. The methodology emphasizes robust model selection and interpretability, addressing the limitations of traditional analytical approaches in capturing the nonlinearities and geometrical complexities inherent to buckling behavior. The dataset, comprising key geometric and mechanical parameters of steel columns, was curated with appropriate preprocessing steps including removal of non-informative identifiers and imputation of missing values. A comprehensive suite of regression algorithms,ranging from linear models to kernel-based regressors and ensemble tree methods,was evaluated. Among these, Gradient Boosting Regression exhibited superior predictive performance across multiple metrics, including the coefficient of determination (R2), root mean squared error (RMSE), and mean absolute error (MAE), and was consequently selected as the final model. Model interpretability was addressed using SHapley Additive exPlanations (SHAP), enabling insight into the relative importance and interaction of input features influencing the predicted axial capacity. To facilitate practical deployment, the model was integrated into an interactive, Python-based web interface via Streamlit. This tool allows end-users,such as structural engineers and designers,to input design parameters manually or through CSV upload, and to obtain real-time predictions of axial load capacity without the need for programming expertise. Applied to the context of steel storage rack columns, the framework demonstrates how data-driven tools can enhance design safety, streamline validation workflows, and inform decision-making in structural applications where buckling is a critical failure mode.
Design Deficiencies, Failure Modes and Recommendations for Strengthening in Reinforced Concrete Structures Exposed to the February 6, 2023 Kahramanmaraş Earthquakes (Mw 7.7 and Mw 7.6)
(Springer, 2025) Erbas, Yasar; Mercimek, Omer; Anil, Ozgur; Celik, Alper; Akkaya, Sercan Tuna; Kocaman, Irfan; Gurbuz, Muhammed
After two major earthquakes centred in Kahramanmara & scedil; on February 6, 2023, in T & uuml;rkiye, there was significant destruction of the building stock. More than fifty thousand people lost their lives, and many people lost their comfort of life even though they were rescued from the wreckage. Researchers have emphasized that this catastrophic consequence is generally caused by design and production errors and low material quality in almost all building types, especially reinforced concrete, steel, masonry, and prefabricated structures. Within the scope of this study, damage patterns and the design flaws of reinforced concrete structures in Malatya, which is one of the provinces affected by the Kahramanmara & scedil; earthquakes, were examined via a field study. During the fieldwork, it was determined that inadequate longitudinal reinforcement and stirrup reinforcement, in-depth reinforcement, and concrete quality, design errors in the column-beam junction area, ignoring the structure-soil interactions, short columns, torsional irregularity, and soft stories were the main factors that led reinforced concrete buildings to be heavily damaged or collapse. After the root causes of damage to reinforced concrete structures were examined, the measures and applications that should be taken to ensure that reinforced concrete structures can maintain their services in the event of earthquakes that are likely to occur in the future was discussed.
Dynamic Identification and Collapse Mechanisms of Unreinforced Masonry Heritage: A Comprehensive Study of Erzurum Atatürk House
(Pergamon-Elsevier Science Ltd, 2025) Okuyucu, Dilek; Eslek, Tumer; Ozdogan, Dursun Burak; Lacin, Tugce; Mercimek, Omer; Kocaman, Irfan
This study presents a comprehensive seismic assessment of the historical Erzurum Atat & uuml;rk House, a representative example of unreinforced masonry (URM) structures in Turkey's high-seismicity region. The research combines experimental and numerical approaches, including operational modal analysis (OMA), detailed finite element modeling, and nonlinear dynamic analyses using nine recorded ground motions. The OMA identified the structure's first three natural frequencies at 3.458 Hz (N-S translation), 3.984 Hz (E-W translation), and 4.264 Hz (torsional mode), with MAC values exceeding 0.9, confirming the accuracy of the calibrated numerical model. Nonlinear time-history analyses revealed critical vulnerabilities, with peak displacements exceeding acceptable limits for all considered seismic scenarios (including 2023 Kahramanmaras, earthquakes). The structure exhibited brittle failure mechanisms characterized by Rapid stiffness degradation; Significant tensile cracking at wall-floor junctions; Out-of-plane failures in upperstory walls; Diagonal shear band formations. Material characterization showed low tensile (0.3-1.07 MPa) and compressive (3-10.71 MPa) strengths, typical of historical masonry with weak lime-based mortars. The force-displacement relationships demonstrated limited energy dissipation capacity, with strength degradation occurring at approximately 10,000 kN lateral load. These findings provide fundamental insights into the seismic behavior of historical URM buildings and establish a methodological framework for their assessment. The study highlights the critical need for further research on performance-based evaluation methods for cultural heritage structures in seismic zones.
The Effect of Kahramanmaras Earthquakes on Historical Malatya Yeni Mosque
(Pergamon-Elsevier Science Ltd, 2024) Kocaman, Irfan; Mercimek, Omer; Guerbuez, Muhammed; Erbas, Yasar; Anil, Ozguer
The earthquakes that occurred on February 6, 2023, in Kahramanmaras , , Turkiye, caused extensive damage, particularly in historical mosques built with traditional methods. This study aims to investigate the collapse mechanism of Malatya Yeni Mosque, which underwent a strengthening operation before the Kahramanmaras , Earthquakes. The primary objective of this study is to offer insights into the rehabilitation of similar structures. Post -earthquake field surveys, combined with finite element modeling and dynamic analysis using city center acceleration data from Malatya, were utilized to assess structural vulnerabilities. The results of numerical analyses and field studies have indicated that seismic damages generally occurred in specific Mosque areas, particularly in the domes, minarets, columns (elephant feet), and arch systems supporting the central dome. The observed damage patterns in these areas signify the zones where the structural inadequacies generally coincide. The main findings of this study shed light on the necessity of strengthening these unique structures exposed to seismic forces and offer an essential step in minimizing the adverse effects of such disasters in the future. This study guides the planning and implementation of efficacious engineering interventions to preserve historical buildings.
Effect of Restoration Interventions on the Seismic Behavior of Historical Masonry Buildings: The Case of Molla Siyah Mosque
(Pergamon-Elsevier Science Ltd, 2023) Kocaman, Irfan
The protection of historical masonry mosques against earthquakes can be achieved by an accurate assessment of nonlinear behavior, such as heavy damage and collapse. For this reason, historical buildings have been strengthened many times in the past and today. To this end, nonlinear analysis of 3D finite element models of structures is a common and reliable approach. This article examines the seismic performance of historical Molla Siyah Mosques, which are defined as cultural assets by the Ministry of Tourism and Culture of the Republic of Turkey, under the influence of earthquake ground motions. It has been investigated how the concrete vault cover applied to the mosque in previous years affects seismic behavior, force-displacement capacity and collapse mechanism of the structure. The mosque has not been studied before using any advanced numerical simulation method. In addition, no studies have been conducted to determine the damage propagation and collapse mechanisms of the mosque. Detailed finite element model was developed by defining the architectural features of mosque. The finite element model was calibrated in the light of the experimental modal analysis results found in the literature. In order to obtain the seismic behavior and collapse mechanisms of the mosques, nonlinear dynamic analyses were performed using the ground motion records from 1992 Erzincan, 1992 Cape Mendocino and 1995 Kobe earthquakes. An evaluation has been made for concrete cover vault in terms of maximum principal strains, maximum displacements, damage distributions and failure mechanisms of the mosque. It has been determined that the reinforcements applied in historical structures can significantly change the seismic behavior of the structures.
The Effect of the Kahramanmaras Earthquakes (Mw 7.7 and Mw 7.6) on Historical Masonry Mosques and Minarets
(Pergamon-Elsevier Science Ltd, 2023) Kocaman, Irfan
The aim of this study is to present the field research and performance evaluation of historical masonry mosques and minarets in 11 different cities in the region shortly after the earthquakes that occurred in Kahramanmaras, Turkey on February 6, 2023. Mosques and minarets were also affected by the earthquakes that occurred in the city of Kahramanmaras, located in the southwest of the Eastern Anatolia region, at 04:17 and 13:24 local time. Mosques and minarets, two types of structures built using masonry building materials and technologies, have been specially studied. Considering the size of the area affected by the earthquake and the diversity of the cultural heritage in the earthquake region, it will take months to reach all of the culturally important structures affected by the earthquake and report them by experts. The structures presented in the article are relatively easy to access and heavily damaged or completely collapsed immediately after the earthquake. Dome collapses, carrier walls and minaret damages are common in his-torical mosques. Minaret damage is concentrated on transition sections and spire parts. In the study, a case of Adiyaman Ulu Mosque, which was completely collapsed in the earthquake, is presented in the analysis. It is seen that the collapse mechanisms obtained by dynamic analysis are very similar to the collapse observed in the mosque after the earthquake. It is thought that the absence of any code or directive for these special structures is a major shortcoming and leaves the engineers in a difficult position during the design and protection phase.
The Effects of the Kahramanmaraş Earthquakes on Historical Masonry Minarets in Hatay, Türkiye
(Springer India, 2025) Kocaman, Irfan; Gedik, Burak; Okuyucu, Dilek
The present study investigates the seismic performance of historical masonry minarets in Hatay province following the 6 February 2023 Kahramanmara & scedil; earthquakes (Mw 7.7 and Mw 7.6). Masonry minarets, which are culturally significant elements of Islamic architectural heritage, are particularly vulnerable to seismic events. The study focuses on 12 damaged minarets, analysing their collapse mechanisms through field observations and finite element modelling. The finite element model of the Payas Sultan Selim Mosque minaret was developed using recorded ground motion data, and the results revealed that the observed collapse mechanism closely matches the numerical predictions. The analysis highlights that the balcony, upper body and spire are the most vulnerable sections due to their slender design and limited tensile strength. Additionally, the study emphasizes the lack of regulations specific to historical masonry minarets, underlining the need for tailored seismic design guidelines. The findings show that preserving architectural integrity by using consistent construction materials is critical for both structural safety and historical authenticity. These results provide valuable insights for preserving historical minarets and developing effective retrofitting strategies to ensure their long-term protection.
Enhancing Seismic Performance of Historic Mosques Through Retrofitting Measures
(Elsevier Science Ltd, 2024) Kocaman, Irfan; Gurbuz, Muhammed
Historic mosques are structures that are highly sensitive to seismic events. Strengthening these buildings, which have been exposed to earthquakes throughout history, and ensuring their safe transfer to future generations is crucial. This research study focuses on three significant historic mosques in the eastern province of Turkiye, Erzurum. Their seismic performance, which has not been extensively studied in the existing literature, is investigated using finite element analysis. Dynamic analyses are conducted, utilizing seismic records from notable earthquakes that have caused significant damage to historic mosques in Turkiye, including the 1992 Erzincan, 1997 Duzce, and 2023 Kahramanmaras, earthquakes. As a result of dynamic analyses, the seismic vulnerability of the considered mosques has been determined. These vulnerable areas include the junctions of load-bearing walls, the dome ring, and the main dome. Based on these findings and considering recommendations from the literature, cost-effective and practical retrofit strategies are proposed to enhance the seismic performance of the mosques. The proposed strengthening aims to improve the interaction between load-bearing walls (diaphragm effect) and reduce displacements in the dome. Dynamic analyses are performed using the retrofitted models to assess the effectiveness of the proposed retrofit measures. These assessments were made considering displacements obtained from the dome and walls and the distribution of global damage. The results of 18 dynamic analyses confirm the efficacy of the suggested retrofit configurations in mosques featuring square plan layouts and single dome architectural styles.
Enhancing Seismic Resilience: A Proposed Reinforcement Technique for Historical Minarets
(Pergamon-Elsevier Science Ltd, 2024) Gurbuz, Muhammed; Kocaman, Irfan
Historical minarets are culturally and architecturally significant structures, often susceptible to substantial damage over time due to different load conditions. Therefore, the reinforcement of such buildings holds paramount importance. This study presented a proposal for strengthening historical rubble stone minarets, exemplified by the minaret of Murat Pasha Mosque in Erzurum, Turkey. A finite element model of the minaret was constructed to comprehend its behavior, with the suggested reinforcement method integrated into this model. The impact of the proposed reinforcement on the minaret's behavior was comprehensively investigated through various numerical methods including modal analyses, pushover analyses, and non-linear dynamic analyses. The analyses revealed that the proposed reinforcement increased the first mode frequency of the minaret by approximately 9.8%. Additionally, it was observed that the reinforcement method augmented the minaret's lateral load-carrying capacity by 58%. Consequently, it was concluded that the proposed reinforcement technique effectively enhances the minaret's resilience under demanding conditions, potentially preventing damage. The proposed reinforcement configuration also significantly alters the collapse mechanism of the minaret, as evidenced by the dynamic analysis results, facilitating a more controlled mode of failure. In this regard, it provides a more secure solution by enhancing the minaret's resilience in an earthquake, thereby reducing environmental safety risks. In conclusion, this study contributes to preserving this invaluable cultural heritage by offering an effective reinforcement method to enchance the seismic resilience of historical minarets. Future research endeavors may further refine these reinforcement techniques and explore alternative material options.
Enhancing the Seismic Resilience of Historical Masonry Cupolas: A Finite Element Study on Cimcime Hatun Cupola
(Springer, 2025) Kocaman, Irfan; Yazici, Casim; Gurbuz, Muhammed
This study investigates the seismic performance and strengthening of the historic Cimcime Hatun Cupola, a representative example of Turkish-Islamic masonry heritage. A detailed finite element (FE) model was developed using material parameters derived from established design codes and literature. Nonlinear time-history and pushover analyses were conducted to assess structural behavior under seismic loading and evaluate a proposed internal steel plate retrofit system. The reinforcement increased the first modal frequency by 2.2 times and improved lateral load capacity by 3.375 times, demonstrating substantial gains in global stiffness and stability. The retrofit strategy, designed to be reversible and minimally intrusive, offers a practical and conservation-compatible solution for similar mausoleum-type structures. The findings contribute to advancing heritage engineering practices by providing a validated numerical approach and a case-specific strengthening methodology applicable to other historical masonry monuments.
Examination of the Damage Limits and Collapse Mechanism of Adıyaman Ulu Mosque with Finite Element Model
(Elsevier Science Inc, 2024) Kocaman, Irfan
Historical masonry mosques are cultural heritage sites that are still actively used today and must be preserved for future generations. These structures, typically featuring load-bearing masonry systems, have been observed to sustain significant damage during various earthquakes. Numerous studies have been conducted to determine the seismic behavior of historical masonry mosques. However, the diverse material properties, damage mechanisms, uncertain geometries, and loading conditions make it challenging to accurately assess their seismic response. In this study, a finite element model of the Ad & imath;yaman Ulu Mosque was created, and time-history analyses were performed using four different ground motions. The mosque was completely destroyed during the earthquakes that occurred on February 6, 2023, in Kahramanmaras, (Mw 7.7 and Mw 7.6). The collapse mechanisms of the mosque were revealed through dynamic analyses. It was shown that the collapse mechanisms obtained from the numerical analysis closely resembled the actual damage observed in the mosque. The finite element models, modeling methods, and material assumptions used in this study were demonstrated to be reliable for determining the damage mechanisms of historical masonry mosques. Additionally, the displacement-based earthquake performance limits of the mosque were determined and compared with recommendations from regulations, guidelines, and literature. The damage limits derived from the dynamic analyses, in light of the observed damage, were found to be significantly lower than the limits recommended for historical masonry structures in the regulations.
Examination of the Damage Limits of a Historical Mosque, Konya Sultan Selim Mosque Example
(Gazi Univ, Fac Engineering Architecture, 2024) Kocaman, Irfan; Kazaz, Ilker
The idealized global base shear force-top displacement relationship of the mosque was determined by drawing a backbone curve that bounds the force-displacement point values (F, D) representing critical actions, such as maximum force, maximum displacement, cyclic unloading paths, initiation and end of strength and stiffness reduction on the hysteresis curves from time-history analysis. Two different material parameters were employed in the analyses to account for the variation in material properties. Values from the linear response region were also taken to clarify the initial stiffness. In addition, the selected (F, D) points include almost all the values in the cycle in which the mosque is considered to have collapsed. Failure was decided by evaluating the load-deformation hysteresis curves and strain values (damage) on the finite element model. The backbone curve was idealized in three-linear form and damage limits of historical Sultan Selim mosque were defined on this curve (Figure A).Purpose:This paper presents the details of the seismic performance evaluation of the historical Konya Karapinar Sultan Selim mosque. The effect of variation in material properties on the seismic performance of historical mosques is examined by employing possible lower and upper bound values of modulus of elasticity (E). It is aimed to determine the reliability of existing damage limits on masonry structures.Theory and Methods: A detailed finite element model of the historical Konya Sultan Selim mosque was created. For modulus of elasticity E=200fc and E=750fc were assigned to finite element models. Nonlinear time-history analyzes were carried out under five different ground motions. The force-drift ratio curves of the mosque were idealized as defined in Figure A. The damage limits for each performance levels of the mosque were determined.Results: The calculated drift ratio limits were found to be lower than the limits recommended in the codes. The results of structural analyses available in the literature also indicate to lower displacement capacity of masonry structures than the collapse limits given in codes. This indicates that existing code limits provides unsafe prediction of seismic performance of masonry mosque. Conclusion: The proposed approach in this study should be applied on different historical mosques to determine more generalized damage limits. It is also noted that the seismic behavior and damage limits of historical mosques are different from other masonry structures.
Experimental and Numerical Investigations of Glued Cross-Laminated Timber Beams Produced with Different Wood Species and Glues
(North Carolina State Univ Dept Wood & Paper Sci, 2025) Bulbul, Ramazan; Keskin, Hakan; Kaya, Musa; Mercimek, Omer; Turer, Abdullah; Kocaman, Irfan; Kopraman, Yagmur
Five-layer cross-laminated timber (CLT) beams made from 17-mm thick lumber pieces were produced using wood from Scots pine (Pinus sylvestris L.), Uludag fir (Abies bommOelleriana Mattf.), and oak (Quercus petraea L.). The outer layers consisted of Scots pine and oak, while the intermediate layers included Scots pine and fir wood. During the layer formation phase in the side-by-side joining press and in the CLT beam formation phase with layers stacked at 90 degrees, polyvinyl acetate (PVAc) and polyurethane (PUR) adhesives were used. After conditioning the CLT beams at 20 degrees C and 65% relative humidity, their dry density values and results from a four-point bending test perpendicular to the adhesive line, including max load, displacement at max load, stiffness, max displacement, and energy dissipation capacity, were evaluated and compared with those obtained using ABAQUS finite element software. The results revealed that timber species, adhesive type, and perforation significantly influenced the mechanical behavior of CLT beams, with oak-based specimens generally outperforming fir and pine in load-bearing capacity. The findings contribute valuable insights into the optimization of CLT beam design for structural applications.
Field Observations and Numerical Modeling of the Collapse Mechanism of the Habibi Neccar Mosque During the 2023 Kahramanmaras Earthquakes☆
(Pergamon-Elsevier Science Ltd, 2025) Dilsiz, Abdullah; Kocaman, Irfan; Mercimek, Omer; Ismail, Salah Haj; Celik, Alper; Anil, Ozgur
The seismic behavior and collapse mechanism of the Habibi Neccar Mosque-recognized as the first mosque in Anatolia and completely destroyed during the 6 February 2023 Kahramanmaras, earthquakes-were investigated through an integrated methodology comprising field observations, structural modeling, and advanced numerical analyses. The structure was modeled using a macro-scale finite element approach with SOLID65 elements in ANSYS, incorporating the Willam-Warnke failure surface to simulate the nonlinear behavior of masonry components. Material properties were derived from experimental studies on regional stone types and engineering correlations. The first three vibration modes obtained through modal analysis revealed dominant translational and torsional behavior, with the first-mode frequency computed as 5.26 Hz. Pushover analyses indicated direction-dependent lateral load capacities: approximately 18,000 kN in the X direction and 14,000 kN in the Z direction. Nonlinear time-history analyses using unscaled ground motion records from the epicentral region demonstrated that the structure entered a collapse mechanism at a dome displacement of +/- 15 mm, with maximum base shear forces reaching 10,000 kN. The dynamic strain distributions confirmed the progressive damage initiated at the dome-arch interface, followed by sequential failure of the vaults, portico, and bearing walls. These results exhibited strong agreement with post-earthquake field observations, validating both the structural modeling strategy and the defined material parameters. Furthermore, the analytical outcomes were found to be consistent with empirical displacement-based collapse limits reported in previous studies. This research emphasizes the importance of displacement-based nonlinear analysis methods in assessing the seismic vulnerability of historical masonry mosques. The presented methodology and findings are expected to serve as a reference framework for the structural evaluation, retrofitting, and restoration of heritage structures located in high seismicity regions.
Global Drift Ratio Limits for Historical Masonry Mosques
(Springer, 2023) Kocaman, Irfan; Kazaz, Ilker
Drift-based performance limits are commonly used in seismic performance assessment. However, many studies have indicated substantial considerations for the displacement-based approach when applied to historical masonry structures. Variability in failure mechanisms, geometrical uncertainties in structural form, loading and boundary conditions and incompatible performance damage limits among codes can be examples to such considerations. This article discusses the reliability of the drift limits recommended in different codes and guidelines by comparing drift values obtained from the time-history and pushover analyses of 11 historical masonry mosques. The effect of material stiffness on the drift capacity of the structures was evaluated in regards to possible lower and upper value of modulus of elasticity in masonry elements. It was determined that the drift values proposed in the codes and guidelines can lead to incorrect and unsafe seismic evaluation on architectural heritage. For historical masonry mosques, global drift ratio values between 0.01-0.07, 0.06-0.25, 0.08-0.45% are recommended for damage limitation, significant damage and near collapse limit states, respectively. Simplified equations incorporating dimensional and mechanical properties are proposed to determine the drift ratio limits of historical mosques.
A Historical Seismic Event Revisited: Stochastic Ground Motion Modeling of the 1859 Erzurum Earthquake and Validations with Structural Damage
(Springer, 2025) Ozdogan, Dursun Burak; Okuyucu, Dilek; Askan, Aysegul; Kocaman, Irfan
Erzurum is one of the major cities in T & uuml;rkiye with high seismic hazard, having a well-documented history of destructive earthquakes. The June 2, 1859 earthquake (Mw = 6.1) caused severe damage to the city, but no ground motion records exist because it occurred before the instrumental measurement period. This study aims to simulate and validate a simulated ground motion record for this historical earthquake using the stochastic finite-fault method. In this approach, fault geometry, stress drop, crustal properties, and local site effects were incorporated to generate realistic acceleration time histories. The simulated record was validated through comparisons with empirical ground motion models and historical damage reports. For validation, detailed finite element models of Erzurum Ulu Mosque and Murat Pasha Mosque were developed and calibrated using Operational Modal Analysis (OMA) data, and nonlinear time-history analyses were performed to assess the consistency of observed and simulated damage patterns. The findings demonstrate that stochastic ground motion simulations can provide reliable insights into historical seismic events, offering a robust framework for reassessing earthquakes without instrumental records and contributing to the understanding of the seismic performance of masonry heritage structures.