Makale Koleksiyonu | İnşaat Mühendisliği Bölümü / Civil Engineering
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Öğe Structural analysis of steel truss and masonry bridge interaction: a case of Ali Fuat Pasha bridge in Sakarya, Türkiye(2023-10-02) Akşar, Bora; Özdemir, Muhammed Alperen; Tutar, Ali İkbal; Çakır, FeritRestoration of historical structures using new materials and techniques is widespread worldwide. In these applications, relatively new materials such as steel, concrete, reinforced concrete (RC), or composite are generally preferred. However, it is often ignored whether old materials and new materials work in compatibility. In this respect, Ali Fuat Pasha Bridge (or Bayezid II Bridge), which was built by Bayezid II in 1495 over the Sakarya River in Geyve-Sakarya, was examined. The bridge is 196.50 meters long and consists of 15 arches with different spans and three arches of the bridge were destroyed as a result of the earthquake. Then, the bridge has been restored by constructing a steel truss system in place of the destroyed arches. Within the scope of this study, the structural performance of the bridge, which is currently serving vehicle and pedestrian traffic, is examined by using finite element analyses (FEAs). Moreover, this research examines the combined behavior of steel and masonry materials and investigates the structural behavior of steel truss and masonry bridge interaction. According to the results of the analyses, there are significant behavioral differences between the masonry structure and the steel structure. The main cause for this disparity is thought to be the varying levels of stiffness and ductility in steel and masonry sections.Öğe A point cloud filtering method based on anisotropic error model(John Wiley and Sons Inc, 2023-12) Özendi, Mustafa; Akça, Devrim; Topan, HüseyinMany modelling applications require 3D meshes that should be generated from filtered/cleaned point clouds. This paper proposes a methodology for filtering of terrestrial laser scanner (TLS)-derived point clouds, consisting of two main parts: an anisotropic point error model and the subsequent decimation steps for elimination of low-quality points. The point error model can compute the positional quality of any point in the form of error ellipsoids. It is formulated as a function of the angular/mechanical stability, sensor-to-object distance, laser beam's incidence angle and surface reflectivity, which are the most dominant error sources. In a block of several co-registered point clouds, some parts of the target object are sampled by multiple scans with different positional quality patterns. This situation results in redundant data. The proposed decimation steps removes this redundancy by selecting only the points with the highest positional quality. Finally, the Good, Bad, and the Better algorithm, based on the ray-tracing concept, was developed to remove the remaining redundancy due to the Moiré effects. The resulting point cloud consists of only the points with the highest positional quality while reducing the number of points by factor 10. This novel approach resulted in final surface meshes that are accurate, contain predefined level of random errors and require almost no manual intervention.Öğe An experimental study on RC beams shear-strengthened with Intraply Hybrid U-Jackets Composites monitored by digital image correlation (DIC)(Elsevier Ltd, 2023-08-22) Çakır, Ferit; Aydın, M. Raci; Acar, Volkan; Aksar, Bora; Akkaya, Hasan CemReinforced concrete (RC) beams are commonly strengthened using steel stirrups, but these materials have limitations such as added weight and susceptibility to corrosion. Fiber-reinforced polymers (FRPs) offer a promising alternative to steel stirrups with high mechanical performance, low density, and resistance to corrosion and chemicals. In particular, Intraply Hybrid Composites (IRCs), which comprise multiple fibers oriented in different directions within a single matrix, have recently gained attention in the construction industry. Cakir et al. [1] investigated the use of three types of IRCs (Aramid-Carbon (AC), Glass-Aramid (GA), and Carbon-Glass (CG)) for strengthening 2-meter-long RC beams (the ratio of shear span (a) to effective depth (d) equals 3 (a/d = 3)) against shear fractures. In this study, the effects of these IRCs on the shear strength of 1.5-meter-long RC beams (a/d = 2) without transverse reinforcement were examined. In this scope, four-point bending tests were conducted on the beams after U-shaped IRC strengthening, and the impact of IRCs on shear strength was evaluated using both digital image correlation and classical measurement equipment such as strain gauges and linear variable differential transducers. The maximum load measured in RC1.5 was 194.50 kN, while the ultimate load capacity reached 265 kN in AC1.5, 246 kN in GA1.5, and 229 kN in CG1.5 after strengthening, representing increases of 36%, 26%, and 18%, respectively, compared to RC1.5. Additionally, the maximum mid-span deflections were determined as 30.40 mm, 16.10 mm, 22.20 mm, and 36.40 mm for RC1.5, AC1.5, GA1.5, and CG1.5, respectively. Moreover, the experimental results were compared with the predictions obtained from the international codes. It should be noted that the failure modes of RC beams are directly affected by the type of IRCs used, highlighting the significant contribution these materials can make to the structural behavior of RC beams.Öğe Examination of delay and travel time at highway toll booths using a micro simulation program: example of Northern Marmara Highway Kurnaköy(2022-04) Özdemir, Ümitcan; Gürsoy, Mustafa; Aksoy, GökerThe aim of this study is to reveal that barrier toll booths are inefficient in terms of delay and travel time when compared to non-barrier toll booths. In our study, Kurnaköy toll booth, on the Northern Marmara Highway, was examined. The toll booth was modeled using the PTV Vissim micro simulation program. Currently, 8 toll booths are in active service and are operated with barriers. As an alternative to the current operation, 4 different operations were modeled: 8 toll booths without barriers, 10 toll booths without barriers, 12 toll booths without barriers and finally 4 toll booths with free passage system. The designed models were run under 3 different demand levels as low, medium and high, and compared using the PTV Vissim program. When the current barrier toll booth and the non-barrier operations were compared with medium demand, it was seen that there is a significant difference in delay. A bottleneck problem was also encountered due to the geometry of the barrier-free toll booth operation. The optimum operation was found by comparing the alternative operations.Öğe Direct usage of occupancy data for multiregime speed-flow rate models(American Society of Civil Engineers (ASCE), 2023-01) Aksoy, Göker; Öğüt, Kemal SelçukEarly macroscopic traffic flow models were based on observations of volume, speed, and density. The invention of traffic sensors has supplied a wealth of data for the development of more accurate macroscopic flow models. However, traffic sensors typically collect volume, speed, and occupancy data. Researchers prefer to convert occupancy to density because of the density usage in earlier models; however, for this conversion, the average length of passed vehicles must be determined. This length is frequently estimated by researchers. However, because the explanatory variable (density) is not observed but produced, this estimation weakens the model results. Considering these challenges, this research proposes a novel traffic flow modeling approach based on occupancy. The proposed method was tested in three speed-flow rate relationship regions, one of which is congested and two of which are free flow. Free flow speed, capacity, queue discharge flow, breakpoint flow rate, and optimum speed can all be determined more precisely with this method. Furthermore, the nonlinear relationship between speed and flow rate was clarified. The proposed traffic flow model is extremely useful, especially for dynamic traffic management applications, because it is based on directly gathered data such as volume, speed, and occupancy.Öğe Identification of sensor location and link flow reconstruction using turn ratio and flow sensors in an arterial network(Taylor and Francis Ltd., 2024) Taşcıkaraoğlu, Fatma Yıldız; Aksoy, GökerIn this article, a quadratic programming problem is considered to identify all link flows in an arterial network when there are unmeasured link flows. A graphical method is provided to determine the minimum number of measurements and sensor locations required to obtain a fully observable model. It is shown that this method is also valid for the augmented graph with turn ratio measurements. If the minimum measurements required are met, a fully determined network can be obtained. If there is not enough measurement, a bound on the magnitude of the resulting inaccuracy in terms of vehicle kilometers traveled (VKT) can be calculated by the proposed linear programming method. The model is that of a queueing network; the parameters describe network geometry, saturation flow rates, turning ratios, timing plan and link flows. Three case studies are conducted to validate this approach. The first two cases are to calculate all missing flows by using a few numbers of measurements and minimum number of measurements required, respectively. Upper and lower bounds in terms of VKT are also calculated for these cases. Third case is to obtain a fully determined network with the minimum number of flow measurements when turn ratio sensors are included. Real measurements are collected from a network in Mugla including 55 links and 16 intersections. Vissim simulator is used to analyze the accuracy of the link flow calculations obtained from the proposed method. The results show that the proposed programming method can calculate the missing flows with a high accuracy and short computation time.Öğe Effectiveness of standalone simulation-based optimization software in optimizing the life cycle cost of residential buildings(Dynamic Academy Yazılım İnşaat San. Tic. Ltd. Şti., 2021-12) Yiğit, Sadık; Ozorhon, BelizDesigners aim to build nearly zero energy buildings and positive energy buildings to comply with regulations. However, due to many variables affecting the energy performance of buildings, energy-efficient building design is a challenging task. Among the proposed methods, simulation-based systems are promising. The proposed simulation-based systems are not suitable for the construction sector because of the long optimization periods. The primary goal of this study is to emphasize the necessity of standalone software packages in solving usability problems and to provide a tool for designers and architects to incorporate into their daily works. To demonstrate the advantages of standalone software a test study was conducted to find a cost-optimal configuration for a typical residential building. In addition, the obtained cost-optimal design was compared to the energy-optimal design obtained in previous studies and it was seen that the outcomes are in parallel with the results of previous studies. It was observed that the optimum insulation thickness obtained from the case study is significantly higher than the limiting values in the national regulation. The results of the parametric analysis demonstrated that wall type, window area, and window type have the highest influence on thermal performance. The results of the study have confirmed that stand-alone software performs optimizations faster overcomes the shortcomings of simulation-based optimization systems comprising integrated multiple software packages.
