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Öğe Assessing a Retrofitting Method for Existing RC Buildings with Low Seismic Capacity in Turkey(Asce-Amer Soc Civil Engineers, 2017) Dere, YunusIn this research, external retrofit of reinforced concrete (RC) buildings, especially the ones located in Turkey, was studied. Most of Turkey's population live in an active seismic zone where frequent earthquakes are experienced. Turkey's existing residential building stock consists mainly of reinforced concrete buildings that are prone to earthquake damage because of a lack of lateral strength. Therefore, a fast and feasible shear retrofit method for these buildings is crucial. In this study, three six-story prototype RC buildings were created to study the effectiveness of external shear retrofit with and without the inclusion of window openings, constructed at building corners. As always desired, this retrofit method was shown to be fast to apply and its construction requires minor damage on the building. The three-dimensional (3D) finite-element model of the building was analyzed nonlinearly by a commercially available software package. The modeling of concrete material as well as embedded steel reinforcement was proved to be satisfactory by calibrating them with three 1/3-scaled RC frame retrofit experiments existing in the literature. The effect of corner shear walls with and without window openings on the base shear capacity and lateral stiffness was assessed comparing with the bare frame. The shear contributions of columns and shear walls for the model buildings were also compared. Considerable amount of capacity increase in base shear and stiffness was achieved by the addition of external shear walls, even with the inclusion of window openings. (C) 2016 American Society of Civil Engineers.Öğe Biomechanical Analysis of Tibiofibular Syndesmosis Injury Fixation Methods: A Finite Element Analysis(Elsevier Science Inc, 2023) Mercan, Numan; Yildirim, Ahmet; Dere, YunusThe optimal treatment strategy after syndesmotic injuries is still controversial. In our study, we aimed to evaluate ideal fixation method in syndesmotic injury by using finite element analysis method. A 3D SolidWorks model file was created by taking computed tomography (CT) images of the area from the right foot base to the knee joint level of a healthy adult male. The intact model, injury model, and 8 different fixation models were created that 3.5 mm screw and suture-button were used in. The models were compared in terms of lateral fibular translation, posterior fibular translation and external rotation of fibula compared to tibia and stress values occurred on screws and suture-buttons. In the hybrid-1 model, lateral fibular translation and external fibular rotation values were obtained as close to the intact model. Von Mises stresses occurred in the screw (435.7 MPa) and suture-button (424.7 MPa) that used in hybrid-1 model was more than single screw at 4 cm model (316.8 MPa) and single suture-button at 2 cm model (160.7 MPa). In the Hybrid-1 model, the screw compensates for posterior fibular translation and external fibular rotation, while the suture-button compensates for lateral fibular translation. Also, the effect of the distal suture-button preventing diastasis in case of proximal screw failure, it was concluded that the hybrid-1 model can be used as a good treatment alternative in the surgical treatment of distal tibiofibular syndesmotic injuries.(c) 2022 by the American College of Foot and Ankle Surgeons. All rights reserved.Öğe Do lateral ankle ligaments contribute to syndesmotic stability: a finite element analysis study(Taylor & Francis Ltd, 2023) Mercan, Numan; Yurteri, Ahmet; Dere, YunusWhether the lateral ankle ligaments contribute to syndesmotic stability is still controversial and has been the subject of frequent research recently. In our study, we tried to elucidate this situation using the finite element analysis method. Intact model and thirteen different injury models were created to simulate injuries of the lateral ankle ligaments (ATFL, CFL, PTFL), injuries of the syndesmotic ligaments (AITFL, IOL, PITFL) and their combined injuries. The models were compared in terms of LFT, PFT and EFR. It was observed that 0.537 mm LFT, 0.626 mm PFT and 1.25 & DEG; EFR occurred in the intact model (M#1), 0.539 mm LFT, 0.761 mm PFT and 2.31 & DEG; EFR occurred in the isolated ATFL injury (M#2), 0.547 mm LFT, 0.791 mm PFT and 2.50 & DEG; EFR occurred in the isolated AITFL injury (M#8). The LFT, PFT and EFR amounts were higher in the both M#2 and M#8 compared to the M#1. LFT, PFT and EFR amounts in M#2 and M#8 were found to be extremely close. In terms of LFT and PFT, when we compare models with (LFT: 0.650 mm, PFT: 1.104) and without (LFT: 0.457 mm, PFT: 1.150) IOL injury, it is seen that the amount of LFT increases and the amount of PFT decreases with IOL injury. We also observed that injuries to the CFL, PTFL and PITFL did not cause significant changes in fibular translations and PFT and EFR values show an almost linear correlation. Our results suggest that ATFL injury plays a crucial role in syndesmotic stability.Öğe Effectiveness of the floating slab track system constructed at Konya Light Rail(Elsevier Sci Ltd, 2016) Dere, YunusGround-borne vibrations and noise, originated at the train/tram wheel-rail interface and transmitted through the rails to the ground, may cause significant disturbance to people passing by or residing alongside the railways. This paper presents a case study on the evaluation of the effectiveness for mitigating ground-borne vibration and noise by floating slab track system (FST). The underpass located at a major road junction in front of Konya Metropolitan Municipality building serves to thousands of people every day. The Konya Light Rail makes a curb right on top of the underpass, which generates considerable amount of noise and vibration to the environment. In this study, the noise and vibration acceleration measurements were taken before and after the FST system installment in order to evaluate the effectiveness of the isolation work. The collected acceleration data were analyzed and the resulting vibration velocity levels were compared. It was found that the vibrations and the ground-borne noise due to the passage of the trams were reduced considerably. The FST system was found to be quite successful in absorbing the vibrations. A noise level reduction up to 26 dBA was measured after replacing the old rail system with FST. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Excessive snow induced steel roof failures in Turkey(Pergamon-Elsevier Science Ltd, 2022) Korkmaz, Hasan Husnu; Dere, Yunus; Ozkilic, Yasin Onuralp; Bozkurt, Mehmet Bakir; Ecemis, Ali Serdar; Ozdoner, NebiIn January 2017, collapses of the numerous roofs were reported due to excessive snowfall in many provinces of Turkey. In this study, the reasons behind the collapses of the steel roofs of 19 factory buildings were investigated. The steel roofs supported by the precast reinforced concrete columns indicated a similar collapse pattern to each other under the unexpected heavy snow loading. The failure mechanisms of the roofs under the snow loading were simulated numerically. Nonlinear finite element models of a typical industrial building were developed and analyzed under an incremental vertical loading that is identical to snow loading. As a result of the analysis, the vertical load carrying capacity of the roof system and the snow load level causing the collapse of roof were determined. The resulting snow load was compared with the snow load values provided by the code specifications. In addition, the collapse mechanism of the steel roof system was analytically determined and compared with the collapse modes observed in the field and the causes of the failure were evaluated. The failure mechanism and the buckling modes obtained from analyses were found very similar to those observed during the site inspections. The main reasons of the roof failures may be attributed to excessive amount of snow caused by climate change and discrepancy of designed project and as-built project due to lack of building inspection control during the construction of the buildings.Öğe Seismic performance improvement of RC buildings with external steel frames(Techno-Press, 2021) Ecemis, Ali Serdar; Korkmaz, Hasan Husnu; Dere, YunusIn this study, in order to improve the seismic performance of existing reinforced concrete (RC) framed structures, various external attachment of corner steel frame configurations was considered as a user-friendly retrofitting method. The external steel frame is designed to contribute to the lateral stiffness and load carrying capacity of the existing RC structure. A six story building was taken into account. Four different external corner steel frame configurations were suggested in order to strengthen the building. The 3D models of the building with suggested retrofitting steel frames were developed within ABAQUS environment using solid finite elements and analyzed under horizontal loadings nonlinearly. Horizontal top displacement vs loading curves were obtained to determine the overall performance of the building. Contributions of steel and RC frames to the carried loads were computed individually. Load/capacity ratios for the ground floor columns were presented. In the study, 3D rendered images of the building with the suggested retrofits are created to better visualize the real effect of the retrofit on the final appearance of the fa?ade of the building. The analysis results have shown that the proposed external steel frame retrofit configurations increased the lateral load carrying capacity and lateral stiffness and can be used to improve the seismic performance of RC framed buildings.Öğe Seismic performance improvement of RC buildings with external steel frames(Techno-Press, 2021) Ecemis, Ali Serdar; Korkmaz, Hasan Husnu; Dere, YunusIn this study, in order to improve the seismic performance of existing reinforced concrete (RC) framed structures, various external attachment of corner steel frame configurations was considered as a user-friendly retrofitting method. The external steel frame is designed to contribute to the lateral stiffness and load carrying capacity of the existing RC structure. A six story building was taken into account. Four different external corner steel frame configurations were suggested in order to strengthen the building. The 3D models of the building with suggested retrofitting steel frames were developed within ABAQUS environment using solid finite elements and analyzed under horizontal loadings nonlinearly. Horizontal top displacement vs loading curves were obtained to determine the overall performance of the building. Contributions of steel and RC frames to the carried loads were computed individually. Load/capacity ratios for the ground floor columns were presented. In the study, 3D rendered images of the building with the suggested retrofits are created to better visualize the real effect of the retrofit on the final appearance of the fa?ade of the building. The analysis results have shown that the proposed external steel frame retrofit configurations increased the lateral load carrying capacity and lateral stiffness and can be used to improve the seismic performance of RC framed buildings.Öğe Strengthening of T-beams using external steel clamps and anchored steel plates(Techno-Press, 2023) Dere, Yunus; Ozkilic, Yasin Onuralp; Ecemis, Ali Serdar; Korkmaz, Hasan HusnuIn order to strengthen the reinforced concrete T-beams having insufficient shear strength, several strengthening techniques are available in the literature. In this study, three different strengthening strategies were numerically studied. First one is affixing steel plates to the beam surfaces. Second one includes tightening external steel bars vertically similar to beam stirrups. The last one is simultaneous application of these two strengthening procedures which is particularly proposed in this work. Available experimental test series in the literature were handled in the study. Finite element (FE) models of reinforced concrete beam specimens having sufficient (Beam-1) and low shear capacity (Beam-2) were created within ABAQUS environment. Strengthened beams with different techniques were also modelled to reflect improved shear capacity. FE simulations made it possible to investigate parameters that were not examined during the previous experimental studies. The results of the analyses were then compared and found consistent with the experimentally obtained data. Experimental and FEM analysis results are in agreement between 1% (closest) and 6%. (maximum). Beam-2 was stregthened with 5 new porposed methods. The rate of increase in shear strength varies between 33% and 64%. It was found that, the strengthening techniques were fairly useful in improving the shear capacity of the considered girder. The model with the proposed strengthening alternative has accomplished a higher load carrying capacity, ductility and stiffness than all of the other models.Öğe Strengthening of T-beams using external steel clamps and anchored steel plates(Techno-Press, 2023) Dere, Yunus; Ozkilic, Yasin Onuralp; Ecemis, Ali Serdar; Korkmaz, Hasan HusnuIn order to strengthen the reinforced concrete T-beams having insufficient shear strength, several strengthening techniques are available in the literature. In this study, three different strengthening strategies were numerically studied. First one is affixing steel plates to the beam surfaces. Second one includes tightening external steel bars vertically similar to beam stirrups. The last one is simultaneous application of these two strengthening procedures which is particularly proposed in this work. Available experimental test series in the literature were handled in the study. Finite element (FE) models of reinforced concrete beam specimens having sufficient (Beam-1) and low shear capacity (Beam-2) were created within ABAQUS environment. Strengthened beams with different techniques were also modelled to reflect improved shear capacity. FE simulations made it possible to investigate parameters that were not examined during the previous experimental studies. The results of the analyses were then compared and found consistent with the experimentally obtained data. Experimental and FEM analysis results are in agreement between 1% (closest) and 6%. (maximum). Beam-2 was stregthened with 5 new porposed methods. The rate of increase in shear strength varies between 33% and 64%. It was found that, the strengthening techniques were fairly useful in improving the shear capacity of the considered girder. The model with the proposed strengthening alternative has accomplished a higher load carrying capacity, ductility and stiffness than all of the other models.
