İnşaat Mühendisliği Bölümü Koleksiyonu

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https://hdl.handle.net/20.500.12428/2661

Listeleniyor 1 - 20 / 38

A Practical Direct Displacement-Based Seismic Design Method for Building Frame Structures
(Wiley, 2025) Eyol, Ahmet; Bozdoğan, Kanat Burak
This paper introduces a practical approach for analyzing frame-type structures within the framework of the direct displacement-based design (DDBD) method. In this approach, frame-type structures are idealized as equivalent shear beams to represent their global seismic behavior. On the basis of this assumption, a series of numerical analyses of equivalent shear beams with varying numbers of stories were conducted in SAP2000, from which relationships for the maximum interstories drift ratio, effective mass, and effective height were established. The derived relationships are presented in tabular and graphical form for practical application, enabling the DDBD method to be applied in a rapid and efficient manner. The proposed method departs from the classical DDBD procedure by modeling the frame system as an equivalent shear beam instead of converting it into an SDOF system. At the end of the study, the proposed method was demonstrated step by step using an example. Additionally, various building types in the literature were analyzed using both the proposed approach and the traditional DDBD method to evaluate the effectiveness and suitability of the new approach. The results demonstrate that the proposed method is highly effective for high-rise buildings with six or more stories. Conversely, for low-rise buildings, it yields higher base shear forces, a consequence of their shorter fundamental periods, when compared with the conventional DDBD method.
Effect of stirrup spacing on strengthening beams with insufficient shear capacity using innovative mechanical steel stitches
(Ernst & Sohn, 2025) Aksoylu, Ceyhun; Uysal, Yusuf; Basaran, Bogachan; Ozkilic, Yasin Onuralp; Arslan, Musa Hakan
This study investigates experimentally and analytically the effect of stirrup spacing variation on the behavior of reinforced beams in the 45 degrees-inclined innovative mechanical steel stitches (MSSs) application for the strengthening of reinforced concrete beams with insufficient shear capacity. Within the scope of the experimental study, four-point loading tests were carried out under vertical loads by selecting stirrup spacing (250, 350, and 450 mm) and MSS spacing (d/3, d/2.5, d/2, d/1.7, and d/1.4) as variable parameters (d is effective depth of beam). In this context, a total of 12 beam specimens with dimensions of 125 x 250 x 2500 mm each with 250 and 450 mm stirrup spacing were produced, one reference specimen with each stirrup spacing and specimens reinforced with five different MSS spacings were tested; in addition, the test results of a reference beam with 350 mm stirrup spacing and beams reinforced with six different MSS spacings in the literature were used for comparison. Within the scope of the analytical study, the MSS spacing required for the beams to reach the flexural capacity was investigated by selecting the ratio of tensile reinforcement and the presence/absence of compressive reinforcement as variable parameters. In the study, the changes in failure mode, strength, ductility, stiffness, and energy consumption capacities of beams due to different stirrup and MSS spacings were analyzed. According to the experimental results obtained at the end of the study, it was observed that the reference beam with 250 mm stirrup spacing carried 32% and 35% more load than the reference beams with 350 and 450 mm spacing, respectively. Tightening the MSS up to 75 mm increased the shear capacity of beams with 450, 350, and 250 mm stirrup spacing up to 46.1%, 37.4%, and 23.5%, respectively. As the stirrup spacing of the reinforced beams decreased, the contribution of the MSS application to the shear capacity decreased. In addition, the failure mode of the beams changed from diagonal tension mode to splitting mode by increasing the MSS spacing. According to the analytical results, it was observed that MSS contributed more to the flexural capacity in beams with low longitudinal reinforcement ratio, and the performance of MSS was significantly improved in the absence of compression reinforcement.
Assessment of Colemanite Waste in Hybrid Fiber-Reinforced Mortars Exposed to Elevated Temperatures
(Springer Heidelberg, 2025) Altun, Muhammet Gökhan; Benlioğlu, Arif; Özen, Süleyman
This study systematically investigates the effects of colemanite waste and hybrid fibers on the high-temperature performance of cementitious mortars, aiming to mitigate the negative impact of colemanite waste on mechanical properties through the use of various fibers, both individually and in hybrid combinations, and thereby providing critical insights for sustainable construction materials. In the study, cement was used as the binder, with colemanite waste substituted at rates of 3, 5, and 7%. Standard sand was used as aggregate, and fibers were incorporated at a volume of 0.4% each of steel fiber, basalt fiber, polypropylene fiber, as well as hybrid fibers (0.2% steel + 0.2% basalt and 0.2% steel + 0.2% polypropylene). The compressive strength, flexural strength, and water absorption rates of the produced mixtures were determined at 7 and 28 days. Additionally, to assess the mechanical performance of the mixtures under high-temperature effects, the 28-day mixtures were exposed to temperatures of 300 and 600 degrees C, and residual compressive and flexural strengths were evaluated. The results indicate that the use of fibers, whether separately or in hybrid forms, enhances the mechanical properties, water absorption capacities, and high-temperature performance of the mixtures, regardless of the substitution ratio of colemanite waste. Among the mortars subjected to high temperatures, the sample containing 7% colemanite waste exhibited the lowest results, whereas the sample, which contained 3% colemanite waste and 0.4% steel fibers, yielded the best results.
Influence of sulfonate and phosphate groups in polycarboxylate ethers on properties of fly ash blended cementitious systems
(Elsevier Sci Ltd, 2025) Altun, Muhammet Gökhan; Karakuzu, Kemal; Özen, Süleyman; Hatungimana, Daniel; Mardani, Ali; El-Mir, Abdulkader; Assaad, Joseph J.
This investigation examines the effect of anionic monomer groups in polycarboxylate ether (PCE) superplasticizers on rheology, setting, compressive strength, and water absorption of cementitious systems containing fly ash additions. Five PCEs having the same backbone structure and different anionic groups are synthesized. The carboxylate functional group is replaced with 10 % or 30 % sulfonate or phosphate groups, while the total anionic monomer content, molecular weight, and side chain length are kept constant. Test results showed that the PCEs containing 30 % sulfonate or phosphate functional groups are effective in improving flow and reduce apparent viscosity, particularly in mixtures containing increased fly ash additions. Because of improved adsorption properties, setting times are extended, which consequently reduces the 1-day compressive strength when the carboxylates are gradually replaced by 10 % or 30 % sulfonate or phosphate functional groups. Yet, the late age strengths and water absorption are not affected by such replacements. Data reported in this paper can be of interest to admixture producers and concrete technologists seeking an efficient performance of PCE polymers in fly ash concrete mixtures.
Shear strengthening of sub-standard reinforced concrete beams with CFRP: Influence of fiber areal weight, wrap scheme and concrete strength
(Elsevier Science Inc, 2025) Alav, Deniz Sarı; Uysal, Yusuf; Aksoylu, Ceyhun; Arslan, Musa Hakan
This study investigates the effectiveness of carbon fiber-reinforced polymer (CFRP) in enhancing the performance of reinforced concrete beams with insufficient shear reinforcement-a common issue in existing low- and highstrength reinforced concrete buildings. A total of 35 one-third scale beams were tested under four-point bending, considering varying concrete strengths (5-70 MPa), CFRP areal weights (300 and 900 g/m2), and wrapping configurations (full (F), U-shaped (U), and side (S)). Key parameters such as load-displacement behavior, energy dissipation, ductility, and stiffness were analyzed in detail. The results demonstrated that CFRP strengthening increased shear capacity by up to 154 % in low-strength concrete (5-20 MPa), while the improvement was limited to 47.2 % in high-strength concrete. Failure modes were significantly influenced by wrapping type: full wrapping led to a 90 % shift from shear to flexural failure, whereas U-shaped and side wrapping achieved only 40 % and 10 % conversion, respectively. Full wrapping also yielded the highest gains in energy dissipation and ductility, while side wrapping alone was largely ineffective. Interestingly, increasing CFRP areal weight did not result in proportional performance gains; in many cases, the 300 g/m2 application outperformed the 900 g/m2 variant. This suggests that poor interfacial bonding and inadequate epoxy impregnation may hinder the effectiveness of higher areal weight configurations. In conclusion, concrete strength, wrapping type, and CFRP areal weight must be considered collectively in shear strengthening strategies. Among these, full wrapping offers the most consistent and reliable improvements in shear capacity, ductility. and energy dissipation.
Effects of shear wall ratio and location on Earthquake performance of reinforced concrete buildings having different ribbed slab configurations
(Elsevier, 2025) Uysal, Yusuf; Serdar, Ali; Aksoylu, Ceyhun; Arslan, Musa Hakan
This study investigates the earthquake performance of reinforced concrete buildings designed with ribbed slab system. Analyses were performed on hypothetical models representing residential buildings in Gaziantep/Islahiye region. In this study, a total of 18 shear wall-frame structure models with three different shear wall placements in accordance with TBEC-2018 were analyzed. Wall density index (0.003, 0.005 and 0.008), shear wall locations defined as M1 (vertically placed on the outer axes), M2 (center-mounted), and M3 (parallel to the outer axes), and ribbed slab placements (parallel and staggered) are considered as variable parameters. The seismic performance of the structures was evaluated using linear and nonlinear analyses. Nonlinear static pushover analyses were used to compare capacity curves, overstrength factor, interstory drift ratios, base shear forces, overturning moments, and second-order effects for each model. As the wall density index increased from 0.003 (%25) to 0.008 (%75), the initial stiffness increased by 158 %, but this increase decreased the plastic deformation capacity and modal displacement values. Models M1 and M3 with walls positioned on the outer axes provided 20.53 % more load carrying capacity than Model M2 with the central wall. The uncracked section shell exhibited 19 %-83 % stiffer behavior, while the cracked sections absorbed more energy. No significant effect of the slab rib arrangement (parallel/staggered) on the stiffness and period was observed. As the shear wall ratio increased, the torsional period decreased by up to 55 %, and the highest torsional strength was achieved in Model M3. Low shear wall ratio models exceeded code drift limits and showed increased interstory drift differences. The results showed that shear wall placement and ratios are critical to seismic performance, and that TBEC-2018 effectively enhances safety in ribbed slab systems.
Susurluk Havzasında Üç Farklı Grid Yağış Veri Setinin Ölçüm Verileriyle Karşılaştırılarak Performanslarının Değerlendirilmesi
(Gazi Üniversitesi, 2025) Saraçoğlu, Fevziye Ayça; Saraçoğlu, Kebir Emre
Son yıllarda, uzamsal-zamansal dağılımı doğru yansıtan uzun dönemli yağış verilerine olan ihtiyaç artmaktadır. Bu ihtiyacı karşılamak amacıyla grid formatında çeşitli yağış veri setleri geliştirilmektedir. Ancak, grid yağış veri setlerinin kullanılmadan önce doğruluklarının ölçüm veri setleriyle kıyaslanarak analiz edilmesi gerekmektedir. Bu amaçla, Susurluk Havzasında 3 farklı aylık grid yağış veri seti (Climatic Research Unit (CRU), Global Precipitation Climatology Center (GPCC) ve University of Delaware (UDEL)) ile ölçüm veri seti aylık, mevsimsel ve yıllık ölçekte 1966-2017 yıllarını kapsayacak şekilde karşılaştırılmıştır. Ölçüm veri seti, Meteoroloji Genel Müdürlüğü’nün Bandırma, Bursa, Dursunbey, Keles, Simav ve Tavşanlı istasyonlarından edinilmiştir. Grid yağış veri setleri ile ölçüm veri seti arasındaki uyum, Belirtme Katsayısı (R2). Kök Ortalama Kare Hatası (RMSE), Ortalama Sapma Hatası (MBE) ve Nash-Sutcliffe Verim İndeksi (NSE) istatistiksel indeksleri kullanılarak değerlendirilmiştir. Grid yağış veri setleri arasında, GPCC genel olarak en iyi performansı sergilerken, CRU en düşük performansı göstermiştir. Ayrıca, grid veri setlerinin düşük rakımlı bölgelerde ölçüm veri setiyle daha uyumlu olduğu gözlemlenmiştir. Yağışlı dönemlerde (kış ve sonbahar), grid yağış veri setlerinin ölçüm veri setiyle daha iyi bir uyum sağladığı tespit edilmiştir.
Numerical Investigation of Transitional Oscillatory Boundary Layers: Turbulence Quantities
(Mdpi, 2025) Baysal, Selman; Özgür Kırca, V. S.
This study investigates the organized flow structures and turbulence quantities in a transitional oscillatory boundary-layer flow over a smooth bed using a DNS model set up by the open-source framework Nektar++ (v5.2.0). The present model was validated against the results of a previous study involving a bypass transition mechanism in the intermittently turbulent regime. To trigger the initial perturbations, a roughness element was placed on the bed and removed at the very moment a two-dimensional vortex tube, caused by an inflectional-point shear-layer instability, was observed on it. Then, the turbulent spots where the flow experienced intense fluctuations in an otherwise laminar boundary layer were identified from the bed shear-stress distribution on the bed, which served as a reliable indicator of turbulence. These flow features emerged as the first sign of the initiation of turbulence. Several measurement points were selected to follow the bed shear-stress variations and to observe the spatial and temporal development of turbulent spots at a low-wave Reynolds number, Re=1.8x105. Along with these observations, phase-resolved turbulence quantities were also investigated over successive half-cycles for the first time in the literature to understand how turbulence develops and spreads over the flow domain. The results show that the turbulence generated in the near-bed region becomes stronger in the deceleration stage due to the adverse pressure gradient and diffuses away from the bed during the subsequent phases of the developing oscillatory boundary-layer flow. The findings related to the turbulence quantities also indicate that the turbulence gradually evolves and spreads into the fluid domain in successive half-cycles.
Assessment of Drought Indices Based on Effective Precipitation: A Case Study from Çanakkale, a Humid Region in Türkiye
(Mdpi, 2025) Saraçoğlu, Fevziye Ayça; Kaynar, Yusuf Alperen
This study investigates the influence of different effective precipitation (Pe) estimation methods on drought index performance in a humid region of Türkiye. The standard precipitation index (SPI) and the reconnaissance drought index (RDI) were compared with their effective precipitation-based counterparts, Agricultural Standardized Precipitation Index (aSPI) and Effective Reconnaissance Drought Index (eRDI), using four Pe estimation methods: USBR (U.S. Bureau of Reclamation), USDA-(Simplified and CROPWAT) (U.S. Department of Agriculture), and FAO (Food and Agriculture Organization). Data from three closely located meteorological stations (Çanakkale, Bozcaada, and Gökçeada) were analyzed across multiple time scales (1-, 3-, 6-, 12-month, and annual). Statistical metrics—coefficient of determination (R2), root mean square error (RMSE), and Nash–Sutcliffe efficiency (NSE)—were used to assess the indices, and trend analyses were conducted using the Mann–Kendall and Sen’s Slope tests. The USDA-Simplified method consistently showed the highest accuracy across all stations and time scales (R2 ≈ 0.99; lowest RMSE ≈ 0.09; NSE > 0.95), while the FAO method performed poorly, particularly at the 1-month scale. Drought frequency and severity were found to increase with time scale, contrary to trends observed in arid regions. Trend analysis revealed no significant changes at short time scales, but statistically significantly increasing drought severity was detected in longer scales, especially in Çanakkale, with slopes reaching up to –0.018 per year. The findings highlight the importance of selecting appropriate Pe estimation methods for accurate drought assessment, even in humid climates, and support the use of aSPI and eRDI with the USDA-Simplified method.
Prescreening of Sedimentation Potential in Harbor Approach Channels: A Parametric Model
(Asce-Amer Soc Civil Engineers, 2025) Baysal, Selman; Kırca, V. Ş. Özgür
In this study, a parametric model was developed to prescreen the sedimentation potential and maintenance dredging frequency for harbor approach channels under the action of combined current and nonbreaking waves. The model is fast, easy to implement, and well-suited for preliminary assessment for a given set of ship, metocean, and sediment characteristics. To resolve the velocity profile, a refined wave-altered current profile was implemented in the model in favor of a simple power-law current profile, which improved the model performance substantially. The model was first validated against the results reported in an experimental study, and then verified against field measurements of the Damietta Harbor approach channel. Finally, a parametric study was conducted to investigate the influences of (1) median grain size of seabed sediment, (2) wave severity, and (3) depth-averaged current velocity on the sedimentation in approach channels. The results showed that the dredging frequency of approach channels is mainly governed by the wave characteristics, i.e., wave severity, in the case of combined waves and current. It was further shown that representing the wave-altered current profile in simplified models is particularly important. Otherwise, the model would yield unrealistically high dredging frequencies when the current velocity approaches zero, even under severe waves.
Tek Boyutlu Zemin Büyütme Analizlerinde Transfer Fonksiyonunun Değiştirilmiş Sonlu Elemanlar Taşıma Matrisi Yöntemi ile Elde Edilmesi
(Afet ve Acil Durum Yonetimi Baskanligi (AFAD), 2021) Bilican, Öznur; Bozdoğan, Kanat Burak; Keskin, Erdinç
In this study, a method is proposed to obtain Transfer functions used in one-dimensional soil amplification analysis. Within the scope of the study, the Modified Finite Element Transfer Matrix (MFETM) method, which was used to find the soil fundamental period in the literature, was adapted to the problem of finding transfer functions used in soil amplification analysis. In the classical finite element method, the system matrix size that increases depending on the number of elements is independent of the number of elements in the MFETM method. At the end of the study, the suitability of the proposed method was shown on two examples. The examples discussed were solved using both the MFETM method presented in this study and the method in the literature, and the results were compared. A program was written in Scilab for the application of the presented method.
Development and validation of a degree of saturation prediction model using time domain reflectometry for compaction control
(Elsevier, 2023) Özgür, Mehmet
Compaction quality is directly related with the shear strength of soils. Inadequately compacted soils have lower shear strength that decrease the load bearing capacity and increase the differential settlement of the pavement, which may endanger safety and durability of the highways. Although intelligent compaction technology has enhanced the quality control of the compaction, conventional evaluation methods adopting sampling from random locations to determine relative compaction are extensively used in most of the earthwork projects. However, relative compaction may lead misjudgment, since the compaction energy level and the soil type inplace cannot match exactly with the given specifications of an earthwork project. Recent studies have shown that soil degree of saturation (Sr) can be utilized as an alternative control parameter for compaction quality. Sr inplace is usually determined with sand cone method. The method is time consuming as well as prone to error due to potential water seepage and deformation of soft soils. With its ability to provide remote and continuous monitoring in real time, Time Domain Reflectometry (TDR) has the potential to serve as a viable alternative method for determination Sr in-place. This research presents models developed using different calibration methods for the prediction of Sr with TDR measured dielectric permittivity. The accuracy of the models was evaluated with cross-validation. The results show that TDR is able to predict the Sr with less than & PLUSMN;5% deviation for 93% of the specimens in the validation set within the saturation ratio range of 0.01-0.93 cm3 cm-3 with an appropriate model.
A Method for Determination of Moment Contribution Ratio under Foundation Rotation in Shear Wall-Frame Systems
(Mdpi, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç
In shear wall-frame systems, the foundation rotation that may occur under the shear walls changes the displacements and interstory drift ratios and changes the internal force distribution. This study investigates the effect of foundation rotations under shear walls on internal force distribution in shear-frame systems. The originality of the study lies in considering parabolic loads and dynamic analysis (first mode), in addition to static uniform or triangular distributed loads, when determining the shear wall moment contribution ratio under the influence of foundation rotation. The shear wall contribution ratio, a key parameter in many earthquake codes, is defined as the ratio of the sum of bending moments taken by the shear walls at the base to the overturning moment. It plays a crucial role in determining the building's behavior. Depending on this ratio, the load-reduction coefficient is changed. This study investigates the effect of foundation rotation on the moment distribution at the base for three different static load cases and the first mode in the dynamic analysis. The multi-story building is modeled as an equivalent sandwich beam. The moment contribution ratio (MCR) was calculated with the help of analytical solutions of the differential equations written for three different load cases in static conditions, and graphs were created for practical use directly calculating the MCR. In the methodology of the study, the initial step involves the calculation of the equivalent sandwich beam stiffness parameters and the foundational rotational spring. Subsequent to these calculations, the MCR values can be directly obtained with the help of graphs. This approach facilitates the rapid and practical determination of the MCR and can be used in the preliminary sizing phase to eliminate possible errors in the data entry of software that performs detailed analysis. In addition, in the presented study, it has been shown that taking a single mode into account is sufficient when calculating MCR values in dynamic analysis.
A Practical Method for Determining Dynamic Characteristics of Buildings Under the Effect of Foundation Rotations
(World Scientific Publ Co Pte Ltd, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç; Öztürk, Duygu
In multi-storey buildings, unforeseen foundation rotations can change the building's behavior. Therefore, these effects should be taken into account in the analysis. In the studies conducted in the literature, the impact of the rotation of the foundation on the building behavior under static loads has been investigated. In this study, an approach is proposed to determine the dynamic behavior of buildings under the effect of foundation rotation, regardless of the type of bearing system. The multi-storey building was modeled as an equivalent flexural-shear beam in the study. In the study, the axial displacements of the columns, which are neglected in the flexural-shear beam model, are also considered, which is different from the literature. The equation of motion representing the dynamic analysis of the equivalent flexural-shear beam was solved with the help of the Differential Transform Method. The period coefficients, effective mass ratio and peak displacement coefficient for five cases were determined and plotted. A code was prepared using Matlab for the analysis with the Differential Transform Method. As a result of the study, the dynamic characteristics obtained depending on the dimensionless building behavior coefficient have been graphed. Using the given graphs, the dynamic characteristics of the buildings under the effect of foundation rotation can be determined quickly and practically. The method presented in this study can be used for Response spectrum analysis of all systems with pure shear beam, pure bending beam and bending-shear beam behavior. In addition, an approach has been proposed to consider P - Delta effects within the scope of the study. The results obtained in the study were interpreted, and the impact of rotation on dynamic characteristics was discussed. At the end of the study, for the convenience of the presented method, two examples, one for wall-frame and the other for frame systems, were solved with the proposed method, and the results were compared with the SAP2000 program.
A Method for Determining the Fundamental Site Period and the Average Shear Wave Velocity
(World Scientific Publ Co Pte Ltd, 2024) Bozdoğan, Kanat Burak; Keskin, Erdinç
The soil-structure interaction plays a crucial role in determining the displacement and internal forces of multi-story buildings subjected to strong ground motion. One of the critical dynamic characteristics influencing soil-structure interaction is the fundamental site period and the average shear wave velocity associated with it. This study introduces an original equation to determine these parameters. In addition, for the first time in the literature, the version of the Rayleigh method used for finding the fundamental periods of buildings is used to find the fundamental site period. The soil is modeled as an equivalent shear beam to obtain the proposed equation. The peak displacement is obtained by acting the soil mass as an external load on the equivalent shear beam. For single-layer soil, the fundamental site period is proportional to the square root of the peak displacement of the equivalent shear beam. The least squares method generalizes the proposed relation for single-layer soils to multi-layer soil profiles. Modified Finite element Transfer matrix method is used for calibration in the least squares method. The equations used in the literature and earthquake codes for determining the fundamental site period and average shear velocity are tested on various examples, and it is shown that the method proposed in this study, along with the Rayleigh method, gives better results than these equations. The performances of these two methods and the five commonly used equations are tested and compared on different soil profiles. Transfer functions, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are used for verification. For all soil profiles, the results obtained from the transfer function, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are found to be in agreement. The true percent relative error found in the results obtained with the proposed method is 4.47%.
Static, Dynamic and Stability Analysis of Tall Buildings by the Transfer Matrix Method Using Replacement Timoshenko Beam
(Springer Int Publ Ag, 2024) Cruz, Mao Cristian Pinto; Bozdoğan, Kanat Burak
In this study, an approach is proposed for the analysis of structures that can be represented by the Timoshenko beam model. In this study, the Transfer matrix method, which has been previously developed in the literature for static, dynamic and stability analysis of all types of multi-story buildings, is formulated in this study specifically for the analysis of symmetric buildings consisting of only shear walls or only frames, which can be represented behaviorally as Timoshenko beams. The size of the Transfer matrix, which is 6*6 in the literature by considering all effects in the symmetric state, is obtained as 4*4 due to the characteristics of the systems considered in this study. In the study, firstly, the differential equation system and boundary conditions representing the Timoshenko beam model were obtained in accordance with Hamilton's principle. Then, the element Transfer matrix was obtained by solving the obtained differential equation system. With the presented approach, both static, dynamic and stability analysis can be performed. The most important advantage of the presented method is that the sizes of the matrices used in the analyses are small. With the Transfer matrix method, the size of both the element and the system Transfer matrix is 4*4. At the end of the study, to show the suitability of the presented method with the finite element method, two examples, one consisting of pure walls and the other consisting of pure frames, were solved with the presented approach and the results were evaluated.
What psychological and socio-demographic factors can influence people's intention to use ridesharing during the war? A case study in Ukraine
(Elsevier Sci Ltd, 2025) Dadashzadeh, Nima; Volkova, Natalia; Ekmekçi, Mustafa; Horpenko, Daniil; Woods, Lee; Nikitas, Alexandros
Public transport services can be disrupted by natural or human-made crises, such as the recent war in Ukraine. Ridesharing has the potential to be used as an alternative to public transport during such crises. However, peoples' attitudes and intentions towards ridesharing during war has not been studied. This study aims to address this critical gap by collecting and analysing travel behaviour data in two Ukrainian cities: Kyiv and Odessa. Exploratory factor analysis identified ten factors influencing ridesharing, namely: attitudes, perceived behavioural control, subjective norm, ease of use, usefulness, moral norms, trust, perceived safety, emotions, and discrimination. Then, a combined conceptual model based on the Theory of Planned Behaviour, and the Technology Acceptance Model was proposed, to incorporate potential psychological and socio-demographic in the context of a war situation. Structural equation modelling was used to explore the causal relationships between these factors and ridesharing. In the context of war, perceived 'usefulness' affected attitudes, while perceived 'ease of use' influenced perceived behavioural control. Moral norms strongly impacted the ridesharing intention; trust influenced attitudes; and gender played a major role by indirectly affecting ridesharing intention. This can provide transport planners and policy-makers with insights as to how ridesharing can be more attractive and become a genuine tool for enhancing human mobility resilience.
A practical modification to coaxial cables as damage sensor with TDR in obscured structural members and RC piles
(Techno-Press, 2023) Özgür, Mehmet; Arsoy, Sami
Obscured structural members are mostly under-evaluated during condition assessment due to lack of visual inspection capability. Insufficient information about the integrity of these structural members poses a significant risk for public safety. Time domain reflectometry (TDR) is a novel approach in structural health monitoring (SHM). Ordinary coaxial cables as is without a major modification are not suitable for SHM with TDR. The objective of this study is to propose a practical and cost-effective modification approach to commercially available coaxial cables in order to use them as a cable sensor for damage detection with the TDR equipment for obscured structural members. The experimental validation and assessment of the proposed modification approach was achieved by conducting 3-point bending tests of the model piles as a representative obscured structural member. It can be noted that the RG59/U-6 and RG6/U-4 cable sensors expose higher strain sensitivity in comparison with non-modified as is versions of the cables used. As a result, the cable sensors have the capability of sensing both the presence and the location ofa structural damage with a maximum aberration of 3 cm. Furthermore, the crack development can be monitored by the RG59/U-6 cable sensor with a simple calibration.
Hasar Görebilirliğin Hakim Periyoda Bağlı Belirlenmesi İçin Bir Yaklaşım: Çanakkale İl Merkezi Örneği
(2024) Bozdoğan, Kanat Burak; Aktan, Selen
Hasar görebilirliğin önemli bir göstergesi göreli kat ötelemesi değeridir. 0.01 göreli kat ötelemesi sınırı ATC-40’a göre hemen kullanım performans seviyesine karşılık gelmekte olup, bu göreli kat ötelemesi sınır değerinin altında binalar elastik davranış göstermektedirler. Bu çalışmada, Çanakkale il merkezindeki düzenli betonarme binaların hasar görmemeleri için hakim periyot değerlerinin hangi aralıklarda olması gerektiği belirlenmiştir. Çalışma; ZC, ZD ve ZE zemin sınıflarında ve DD-1 ve DD-2 deprem düzeyleri için gerçekleştirilmiştir. Bu kapsamda, maksimum göreli kat ötelemesi oranının belirlenmesi için salt perdeli yapılar için eğilme kirişi kabulü yapılırken, salt çerçeveli yapılar için kayma kirişi kabulü yapılmıştır. Çalışmada literatürden farklı olarak daha gerçekçi sonuçlar elde etmek için eğilme kirişi ve kayma kirişi modelinde kütleler ayrık olarak kat hizalarında dikkate alınmıştır. Bu modelden yararlanılarak maksimum göreli kat ötelemesi oranı için hakim periyoda bağlı bir bağıntı SAP2000 programı yardımıyla elde edilmiştir. Elde edilen bağıntı 0.01 göreli kat ötelemesi değerine eşitlenerek binaların hasar görmemesi için gereken minimum hakim periyot değerleri hesaplanmıştır. Elde edilen sonuçlar grafik ve tablolar üzerinde gösterilerek sonuçlar yorumlanmıştır.
A method for calculation of lateral displacements of buildings under distributed loads
(Kyrgyz-Turkish Manas University, 2023) Öztürk, Duygu; Bozdogan, Kanat Burak; Aydın, Süleyman
Lateral displacement is a vary important parameter that we need to calculate when structures are subjected to lateral loads like earthquake and wind loads. In this study, a method is proposed for lateral displacement calculation of structures with different structural systems in different planes. This method is based on the continuum system calculation model. The method suggested in the literature for only top displacement in the case of uniform loading, is developed in this study for the calculation of displacements at each storey level and also in both uniform and triangular loading conditions. At the end of the study, twenty-eight storey building with shear wall-frame bearing system, which was taken from the literature, was solved with the presented method and Finite Element Method. The shear walls were modelled with three different element types for the analysis with the Finite Element Method with structural engineering program used. The results, obtained from the Continuum Method and Finite Element Method were presented in tables and by figures. Thus, the compatibility of the proposed method with the classical Finite Element Method was investigated. From the compared results of the method and the literature or finite element models it was seen that the method used for the case of uniform or triangular distributed loading gives very close results.

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