Journal of Structural Engineering & Applied Mechanics

Seda Öncü-Davas

Türkiye is located in a region of high seismic hazard due to the dense distribution of active fault lines. Major earthquakes that have occurred in the country, particularly the 1999 Kocaeli and 2023 Kahramanmaraş events, have demonstrated not only the devastating potential for loss of life but also the critical importance of maintaining the functional performance of buildings after seismic events. In this context, seismic isolation systems, which extend the building period to reduce earthquake forces and dissipate energy at the isolation level, have gained increasing attention and application in recent years. However, the design parameters of such systems vary depending on the local soil class, seismic intensity level, and geographical coordinates. In this study, a preliminary design of lead rubber bearings (LRBs) was conducted for a typical five-story reinforced concrete building using the data provided by the Turkish Earthquake Hazard Map (TDTH). For each soil class (ZA, ZB, ZC, and ZD), preliminary design results were obtained across all geographical coordinates in the TDTH and subsequently transferred to a GIS-based QGIS environment. The spatial distributions of isolator diameter and base displacement demands were mapped, and these parameters, together with the effective period, characteristic strength ratio, and effective damping ratio, were statistically evaluated to identify regional trends under different soil conditions. Accordingly, this study provides engineers and practitioners with an order-of-magnitude assessment of how soil class influences the preliminary design parameters of seismic isolation systems across Türkiye, based on a representative five-story building equipped with lead rubber bearings, through both statistical and geospatial analyses.

https://doi.org/10.31462/jseam.2025.04246260

Alperen Türkay

The Turkish Earthquake Code 2018 (TEC-2018) has been in use in Türkiye since January 1, 2019. Before this date, the Turkish Earthquake Code 2007 (TEC-2007) was in use. The earthquake zone map, which represents the country’s seismic risk zones, was also updated as of January 1, 2019. In this study, the seismicity of Sivas city was investigated in consideration of the requirements of two codes. A four-story reinforced concrete building was used as a sample building. Structural analyses were performed using the ETABS software. Seismic calculations of the sample building were performed for all districts of Sivas using the response spectrum analysis, a linear calculation method. As a result of the analyses, modal analysis results, design spectra, base shear forces, and roof displacements were obtained for the strongest and weakest local soil classes of the earthquake codes. The results were compared to evaluate the differences between the two codes, specifically for Sivas province. The fact that Sivas districts have different seismic risks made the comparison of the codes more detailed. Thus, results were obtained and compared for different seismic risk zones. The numerical results showed that the values obtained according to TEC-2018 were greater than those obtained according to TEC-2007, especially in weak soils. The comparisons revealed that TEC-2018 was more detailed.

https://doi.org/10.31462/jseam.2025.04261278

Barış Bayrak

This research examines the feasibility of using waste fibers (yarn, fabric, hemp, plastic, iron powder, and iron shavings) as substitute shear reinforcements in slag-based geopolymer concrete (GPC) beams devoid of stirrups. It also compares their performance with that of beams reinforced with industrial fibers (steel, glass, and basalt). Beams measuring 50x150x750 mm were produced with 1% different waste and industrial fibers and subjected to three-point bending tests. The samples conducted were ten beams, which underwent three-point bending tests in relation to their load-deflection behavior, crack pattern, failure mode, strain distribution, energy dissipation, residual strength, and toughness. The findings show that industrial and waste fibers considerably improve the tensile strength of the GPC, preventing crack propagation and improving shear capacity. But performance is fiber type dependent. Among the waste fibers, hemp fibers made the highest contribution with respect to shear capacity, energy dissipation, and toughness compared to the other waste fibers and even to commercial fibers. On the contrary, iron powder had limited performance improvement, which was probably due to its low capability of bridging cracks. Among all the industrial fibers used, basalt and glass fibers exhibited the best compatibility with the GPC matrix, leading to the highest residual strength and toughness. Hemp and fabric are waste fibers; however offer the highest levels of energy dissipation owing to their pliability and high energy absorption. Moreover, the research indicates that the experimental shear capacity is also lower than the values predicted by international codes, including ACI318-19, Eurocode-2, and the fib Model Code 2020. These codes were found to be underestimating the shear strength of GPC beams, indicating a need for customized proposals. Thus, the research highlights the possibility of waste fibers as being sustainable and cost-effective for the reinforcement of geopolymer concrete.

https://doi.org/10.31462/jseam.2025.04279311

Gökhan Dok Ali Bertu Saglam

In this study, the effect of earthquake record scaling on the seismic behavior of high-rise reinforced concrete structures was investigated within the scope of the Turkish Building Earthquake Code (TBEC-2018). A 27-story reinforced concrete building with a shear wall–frame structural system was analyzed using both linear and nonlinear methods. In the linear analysis phase, the structural design was carried out according to the strength-based design approach (SBD) and the modal combination method defined in TBEC-2018. In the nonlinear analyses, the deformation-based assessment (DBA) approach was adopted, and nonlinear time-history analyses (NTHA) were performed. Eleven real earthquake records were scaled in accordance with the horizontal elastic design spectrum defined for the DD-1 earthquake level (the maximum considered earthquake with a 2% probability of exceedance in 50 years, corresponding to a return period of 2475 years) and the requirements of TBEC-2018 using the simple scaling method. The results obtained from the analyses performed with both scaled and unscaled earthquake records were evaluated in terms of relative story drifts, base shear forces, plastic rotation demands, and unit deformations in structural walls. The findings indicate that scaled earthquake records significantly influence deformation demands and the energy dissipation capacity of high-rise buildings. Moreover, the results suggest that the applicability of the performance limit values defined in TBEC-2018 to nonlinear analyses of tall buildings should be further examined.

https://doi.org/10.31462/jseam.2025.04312330

Zeki Baran Alper Polat

This study investigates the electromagnetic field (EMF) permeability characteristics of widely used construction materials to determine their effectiveness in electromagnetic insulation against radiation emitted by base stations. Field measurements were conducted at 81 base stations located in the city center of Diyarbakır in accordance with the standards of the Information and Communication Technologies Authority (ICTA). Test materials included concrete, brick, wood, metal, lead, PVC, XPS, and recycled concrete. The results indicate that the highest average electromagnetic field intensity was measured in free-space conditions (3.37 V/m), whereas lead exhibited the most effective shielding performance with an average value of 1.01 V/m, corresponding to an attenuation of approximately 70%. Metal sheets also showed strong shielding capability with an average value of 1.29 V/m. Among conventional materials, recycled concrete demonstrated lower electromagnetic permeability (2.13 V/m) compared to standard concrete (2.60 V/m). Thickness-dependent measurements revealed that increasing recycled concrete thickness from 3 cm to 7 cm reduced electromagnetic field intensity from up to 2.93 V/m to as low as 1.64 V/m, representing a reduction of approximately 44%. Measurements conducted inside and outside the safety distance further confirmed that EMF levels outside the safety distance can be more than twice those measured inside. Overall, the findings demonstrate that material type, thickness, and safety distance play a critical role in reducing electromagnetic exposure. Recycled concrete emerges as a sustainable and effective alternative for electromagnetic shielding in building design.

https://doi.org/10.31462/jseam.2025.08331347

Hamdi Kuleyin

Enhancing the crashworthiness and energy-absorption capacity of lightweight tubular structures is essential for improving safety while meeting modern demands for weight reduction in engineering applications. This study aims to investigate the effects of sinusoidal corrugation patterns with variable wall thickness on the crashworthiness behavior of circular thin-walled tubes. A validated 2D axisymmetric finite-element model was developed in LS-DYNA, and corrugated tube configurations were designed with one-sided (OS) and double-sided (DS) thickness variations, and their quasi-static compression responses were examined. The results revealed that corrugation geometry significantly enhances crashworthiness characteristics compared to a straight tube. The OS-2.75 configuration exhibited the most pronounced improvements, achieving increases of 31% in mean crushing force, 34.3% in total absorbed energy, and 13.5% in specific energy absorption (SEA). Meanwhile, the DS-2.75 model showed enhancements of up to 24% and 20% in mean crushing force and total energy absorption, respectively, with the DS-2.5 tube offering a favorable balance between mass reduction and improved performance. The findings demonstrate that corrugation-based thickness tailoring is a robust and efficient design strategy for improving the crashworthiness of thin-walled tubes. The presented approach offers valuable guidelines for the development of lightweight energy-absorbing components in automotive, aerospace, and protective engineering applications.

https://doi.org/10.31462/jseam.2025.04348361

İlkem Turhan Çetinkaya Pembe Merve Karabulut Hüseyin Oğuz İsa Çömez

In this study, the contact problem in a functionally graded (FG) layer resting on a Kerr foundation is considered. The Kerr foundation is a foundation system that has two springs with a shear plate in between. It is assumed that the thickness of the FG isotropic layer is h, and it is indented by a cylindrical punch. Moreover, the layer is loaded by a concentrated force. The shear modulus of the layer is assumed to vary exponentially in the thickness direction. The body forces are neglected. The boundary conditions of the problem are determined considering the geometry of the problem. The problem is modeled as a singular integral equation using the Fourier integral transform technique, the basic equations of elasticity theory, and the boundary conditions of the problem. The singular integral equation is solved numerically using the Gauss-Chebyshev method, in which the singular integral equation leads to a system of algebraic equations. The effects of material inhomogeneity, indentation load, and foundation parameters on the contact behavior are examined. The detailed mechanical analysis is presented.

https://doi.org/10.31462/jseam.2025.04362372

Oğuzhan Çelebi

The ground accelerations recorded during the February 6, 2023, Kahramanmaraş earthquakes exceeded the design acceleration values specified by the Turkish Earthquake Codes enforced between 1975 and 2018. This paper examines the effect of ground acceleration intensity on the seismic performance of typical RC buildings that are representative of the construction practice governed by the 1975 Earthquake Code and the TS 500 standard. Within this scope, two hypothetical RC frame buildings with equal story numbers and with similar plan areas, assumed to be located in the Hatay–Defne region, were modeled. Both buildings were designed according to the provisions of the 1975 code; however, one building was configured to have a regular and symmetric plan layout, while the other one had a plan and asymmetric stiffness distribution. Equivalent static analyses based on the 1975 code and linear time-history analyses by using the real ground motion records, including the record of the February 6, 2023, Pazarcık event, spectrally scaled according to TBEC 2018, were performed. The seismic responses of the buildings were evaluated in terms of floor accelerations, top displacements, base shear forces, and inter-story drifts. In addition, the natural periods and frequency contents obtained by FFT analyses are examined. The results indicate that although increasing ground acceleration significantly amplifies seismic demands in both buildings, the presence of plan irregularity and non-uniform stiffness distribution leads to markedly higher drift and acceleration demands. Consequently, it is concluded that ground acceleration alone cannot explain any probable collapses, and structural configuration and code-based design assumptions play a decisive role in the seismic performance of RC buildings that were designed according to the 1975 Earthquake Code.

https://doi.org/10.31462/jseam.2025.04373399