Journal of Structural Engineering & Applied Mechanics

Furkan Şen Fezayil Sunca Yunus Emrahan Akbulut Mert Hacıemiroğlu Sara Mostofi Esengül Çavdar Murat Günaydın Cenk Alhan Gökhan Özdemir Ertuğrul Taciroğlu Ahmet Can Altunışık

The study investigates how model configuration assumptions in heat-transfer modelling affect the thermal field and the post-fire mechanical performance of lead–rubber bearings (LRBs). Because prior studies generally model only the isolator while others include connection components, the authors address this gap by comparing three FE model configurations: A) isolator only, B) isolator+upper/lower steel flange plates, and C) isolator+flange plates+connected RC column. Thermal and mechanical analyses are performed in ANSYS Workbench. Fire exposure is defined using the ISO-834 standard fire curve with 20, 30, and 40 minutes of heating, resulting in nine scenarios (3 configurations×3 durations). Temperature-dependent degradation of rubber properties is incorporated in the thermo-mechanical phase; peak nodal temperatures from the thermal analysis are transferred as the initial thermal state for the structural model. Mechanical loading includes 10 MPa vertical compressive stress and lateral displacement corresponding to 100% shear strain. Results show that post-fire horizontal stiffness and strength degradation increase with fire duration and depend strongly on the model configuration. Configurations B and C exhibit a clear reduction in horizontal stiffness after fire exposure, while the isolator-only case (A) shows the smallest deviation from the pre-fire response. The inclusion of steel flange plates (B) leads to more pronounced degradation, consistent with intensified heat transfer into the isolator; adding the RC column (C) slightly moderates thermal transfer compared with B but still produces significant post-fire softening. Overall, the study highlights that neglecting flange plates and connected structural elements can underestimate internal temperature distribution and misrepresent post-fire performance, underscoring the need to include these components in FE modelling for realistic fire assessment.

https://doi.org/10.31462/jseam.2026.676

Fatma Ülker Peker

In this study, the application of Stability Functions and Tangent Stiffness Methods has been used to determine the geometrically nonlinear analysis of steel structures. The stability functions method is an iterative method that takes into account the axial forces occurring in the structural elements. The majority of the methods developed for the nonlinear analysis of structures are successive approximation methods. Stability functions have been used in the calculation of second-order effects accurately and in the consideration of geometrically nonlinear behavior with an iterative technique. In the tangent stiffness method, the nonlinear behavior of the structure has been obtained using iterative linear elastic analyses. In each iteration, the equilibrium equations have been rewritten in the deformed position of the structure, the geometric stiffness matrix has been established, and the compensation load vector has been applied to the system to balance the joint displacements. Both developed algorithms are coded with the Visual Basic .NET programming language. To demonstrate the application of the algorithms, the analysis of a 2-plane frame and 1-space truss system with unhindered lateral stability is performed, and the results are compared. In addition, the analysis and comparison of the same problems are made with the “P-Delta plus Large Displacements” option in SAP2000 software. The obtained results show good agreement with the benchmark solutions and the SAP2000 analyses, thereby confirming the accuracy and reliability of the proposed computational algorithms for geometrically nonlinear structural analysis.

https://doi.org/10.31462/jseam.2026.722

Sila Avgin Mehmet Metin Köse Erkan Biçici

Accurate estimation of lateral displacement in reinforced concrete (RC) columns is essential for performance-based seismic assessment. Total lateral displacement consists of flexural, bar-slip, and shear deformation components; however, commercial structural analysis platforms such as SAP2000 generally consider only flexural deformation, which may lead to overestimation of stiffness and inaccurate prediction of deformation capacity in non-ductile members. Although advanced nonlinear finite element platforms such as OpenSees explicitly represent these mechanisms, their implementation typically requires considerable modeling expertise and computational effort. This study presents a displacement component-based modeling framework within SAP2000 to represent flexural, bar-slip, and shear deformations through a component-based plastic hinge formulation. Rather than proposing new analytical formulations, the framework provides a practical and reproducible implementation strategy for representing individual deformation mechanisms within a commercial structural analysis platform. The proposed methodology is validated against the cyclic responses of an experimental database comprising 24 RC column specimens and is further compared with fiber-based OpenSees simulations in terms of lateral load–displacement response, stiffness degradation, and hysteretic behavior. The results demonstrate good agreement with the experimental responses, indicating that the proposed framework can effectively represent the nonlinear cyclic response of RC columns while explicitly accounting for the contributions of individual deformation mechanisms. The proposed methodology offers a practical intermediate nonlinear assessment approach between simplified engineering models and computationally demanding distributed-plasticity simulations for the seismic performance evaluation of existing RC structures.

https://doi.org/10.31462/jseam.2026.735

Recep Suk

In this study, a reinforced concrete (RC) building with inadequate seismic performance was designed below the requirements of TBEC 2018 and retrofitted using RC jacketing, friction dampers, and a hybrid approach. Subsequently, seismic performance, damage states, periods, and base shear forces were evaluated through nonlinear static pushover analyses, and their effects on cost were compared with those of the reference structure. Based on this study, it was determined that 50% of the ground and second-floor beams in the reference structure were identified at the Limited Damage (LD) level, while the remaining 50% were classified at the Moderate Damage (MD) level. Among the ground-floor columns, 36% were identified at the Advanced Damage (AD) level and 64% at the Collapse level. Above the second floor, all columns and beams in both the reference and retrofitted structures exhibited damage corresponding to the LD performance level. Accordingly, the reference structure was considered to have reached collapse in accordance with TBEC 2018. Following RC jacketing, 70% of the ground floor beams were identified at the LD level and 30% at the MD level, whereas all second-floor beams remained at the LD level. For the ground- and second-floor columns, 60% were identified at the LD level and 40% at the MD level, corresponding to the Life Safety (LS) or Controlled Damage (CD) performance level. Following friction damper retrofitting, 50% of the ground- and second-floor beams were identified at the LD level and 50% at the MD level. All ground-floor columns were classified at the MD level, whereas the second-floor columns were identified at the LD level, corresponding to the LS performance level. The hybrid retrofit resulted in 40% of the ground-floor columns being identified at the LD level and 60% at the MD level, while 72% of the second-floor columns were identified at the LD level and 28% at the MD level. Finally, 77.5% of the ground-floor beams were identified at the LD level and 22.5% at the MD level. Overall, all strengthening methods significantly improved seismic performance, while RC jacketing and the hybrid system reduced structural periods but increased base shear forces to approximately 1.5 times those of the reference structure. Consequently, foundation moments increased by 358% and 239% in the RC jacketed and hybrid systems, respectively, whereas the friction damper system showed only a 6% increase. These higher foundation demands may increase retrofitting-to-replacement cost ratios for the RC jacketing and hybrid systems. Thus, despite the improved seismic performance, retrofitting cost remains a key factor in strengthening strategy selection.

https://doi.org/10.31462/jseam.2026.737

Asuman Isil Carhoglu Kasim Armagan Korkmaz

Damage to arch dams during a powerful earthquake can result in significant loss of life and property. Therefore, in order to prevent damage or destruction that may develop during a major earthquake, it is extremely important to determine how the arch dams will behave under the influence of earthquakes with different characteristics. For this reason, a parametric study is performed to determine the behaviour of Karakaya Dam under seismic loads by considering the different seismic conditions. Structural responses of Karakaya Dam under the influence of earthquakes with different characteristics were obtained and compared. It was determined that the different characteristics of ground motions are of great importance to the structural response of the dam. It was shown that the frequency content of seismic motions and earthquake properties are of great significance in terms of defining the seismic performance of the dam. It was revealed that changes in the structural behaviour forming in the dam body due to changes in ground motion, where the arch dams were sensitive to seismic records. In the formation of this difference, parameters such as peak ground acceleration, ground velocity, and frequency content of the earthquake have been shown to be effective. To determine the frequency matching between the structure and seismic motions, power spectra of seismic motions were obtained, and the frequency relationship between Karakaya Dam and ground motion was evaluated.

https://doi.org/10.31462/jseam.2026.758

Chaitanya Bhargav Nerella Jayaprakash Vemuri Sri Kalyana Rama Jyosyula Rajaram Chenna

Ground motion directionality under pulse-like excitation significantly affects structural demand in tall buildings, but its interaction with lateral force-resisting systems is not fully quantified. This study investigates the orientation-dependent response of a rectangular reinforced concrete building subjected to pulse-like motions from the 2023 Turkey earthquake. Four structural configurations are investigated: a regular moment-resisting frame, a shear wall system, a fluid viscous damper system, and a combined system. Bidirectional ground motions are rotated from 0 to 180 degrees and evaluated using time-history analysis with the Fast Nonlinear Analysis procedure. Since peak responses in orthogonal directions do not occur simultaneously, the governing roof displacement at each orientation is defined as the maximum absolute peak response in the principal directions. Dispersion, normalization, and exceedance-based performance indices are used to quantify directional variability and system effectiveness. The mean DSIe values are 0.212, 0.188, 0.318, and 0.313 for the regular, fluid viscous damper, shear wall, and combined configurations, respectively, with the FVD configuration reducing mean directional dispersion by approximately 11.3% relative to the regular frame. The mean NSER of the FVD configuration is 0.858, indicating an overall reduction in roof displacement, although a maximum NSER of 1.336 occurs for GM 4631 at 6°. The dominant pulse periods exceed the fundamental periods of all configurations, indicating long-period pulse characteristics relative to the structural periods. The findings indicate that orientation-dependent pulse-structure interaction can change the relative effectiveness of the investigated stiffness- and damping-based systems, emphasizing orientation-dependent evaluation in performance-based seismic design.

https://doi.org/10.31462/jseam.2026.769