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Article Citation - WoS: 1Citation - Scopus: 1Experimental Determination of Resistance Characteristics of Support Details Used in Prestressed Concrete Bridge Girders(Asce-amer Soc Civil Engineers, 2009) Baran, Eray; Rohne, Ryan; French, Catherine E.; Schultz, Arturo E.Static load tests were performed on support details used at the ends of prestressed concrete pedestrian bridge girders to determine the resistance characteristics of girder supports in the direction perpendicular to the longitudinal axis of the girders. The specimens tested represent support details that have also been widely used in prestressed concrete highway bridges in Minnesota and in other states. Two specimens, one representing the free-end detail and one representing the restrained-end detail were subjected to a combination of vertical and lateral loads. The applied loading was intended to simulate the loading conditions to which the girder ends would be subjected in the event of an over-height vehicle collision with the bridge. The tests revealed two types of lateral load resisting mechanisms depending on the type of support detail. The specimen with the free-end detail resisted the lateral loading through sliding friction between the components of the support assembly. Deformation of this specimen was a combination of shear deformation of the bearing pad and sliding of various support components. The restrained-end detail exhibited larger lateral load capacity than the free-end detail due to the resistance provided by the anchor rods that were intended to prevent the lateral movement of the girder ends. Failure of the specimen with restrained-end detail was due to the concrete breakout and bending of the anchor rods.Article Citation - WoS: 106Citation - Scopus: 141Flexibility Based Approach for Damage Characterization: Benchmark Application(Asce-amer Soc Civil Engineers, 2004) Bernal, D; Gunes, BA flexibility based damage characterization technique is described and its performance is examined in the context of Phase 1 of the benchmark study developed by the IASC-ASCE SHM Task Group. Noteworthy features of the analytical development are: (1) the methodology used to extract a matrix that is proportional to the flexibility when the excitation is stochastic; (2) the technique used to interrogate the changes in flexibility (or flexibility proportional matrices) with regards to the location of the damage; and (3) the method used to quantify the damage without the use of a model. The strategy proved successful in all the cases considered.Article Citation - WoS: 21Citation - Scopus: 28Damage in Reinforced-Concrete Buildings During the 2011 Van, Turkey, Earthquakes(Asce-amer Soc Civil Engineers, 2014) Baran, Eray; Mertol, Halit Cenan; Gunes, BurcuTwo major earthquakes with magnitudes Mw=7.2 (ML=6.7) and ML=5.6 occurred in eastern Turkey on October 23 and November 19, 2011. The maximum measured peak ground accelerations for the two ground motions were 0.18g and 0.25g, respectively. The earthquakes resulted in various levels of damage to RC moment-resisting frame buildings ranging from minor cracking in brick partition walls to total collapse. This paper summarizes the field observations of the Atilim University Reconnaissance Team carried out in the region a few days after the two main shocks with an emphasis on the performance of RC buildings. A summary of the evolution of the Turkish seismic design code during the last 35 years is given, followed by an explanation of the behavior of RC buildings during the October 23 and November 9 earthquakes. The deformation types that were commonly observed in the heavily damaged or collapsed RC buildings include plastic hinging in columns attributable to stiffer beams, localization of damage in ground-story columns attributable to changes in the stiffness of the lateral load-resisting system caused by brick partition walls, and shear failure of columns caused by discontinuities in the partition walls adjacent to the columns. Poor concrete quality, inadequate development and lap splice length for reinforcement, and inadequate confinement in columns also contributed to the poor seismic behavior.Article Citation - WoS: 30Citation - Scopus: 29Acoustic Control of Flow Over Naca 2415 Airfoil at Low Reynolds Numbers(Asce-amer Soc Civil Engineers, 2016) Genc, M. Serdar; Acikel, H. Hakan; Akpolat, M. Tugrul; Ozkan, Gokhan; Karasu, IlyasIn this study, the effects of acoustic excitation frequency on flow over an NACA 2415 airfoil were determined, and all of the experiments were done both with and without the presence of the acoustic excitation. The acoustic excitation was applied for a range of angles of attack (0 degrees-25 degrees) and Reynolds numbers of 50,000, 75,000, 100,000, 150,000, and 200,000. To examine the effects of acoustic excitation on the flow, force measurements, pressure measurements, hot-wire anemometry, smoke-wire flow-visualization, and particle image velocimetry techniques were employed. The results indicated that for stall and some limited poststall angles of attack of the acoustic excitation having a frequency in a certain range forced the separated shear layer to reattach to the surface of the airfoil. As the Reynolds number increased, the effective excitation frequency increased, but the range of Zaman number [St/(R-1/2)] was the same. With the acoustic excitation, the stall angle was delayed from 12 degrees to 16 degrees at R = 50,000, and there was a 30% and 50% increase on the maximum value of the lift coefficient and the ratio of the lift and drag forces, respectively. Moreover, the stall angle was delayed from 13 degrees to 17 degrees at R = 75,000, from 15 degrees to 18 degrees at R = 100,000, from 15 degrees to 17 degrees at R = 150,000. Furthermore, it was concluded that acoustic excitation shrunk laminar separation bubble, and an effect of the acoustic control on the separation bubble decreased as the Reynolds number increased. (C) 2016 American Society of Civil Engineers.Article Citation - WoS: 13Citation - Scopus: 23Numerical Analysis of a Tunnel Support Design in Conjunction With Empirical Methods(Asce-amer Soc Civil Engineers, 2008) Sari, Yasin Dursun; Pasamehmetoglu, A. Gunhan; Cetiner, Erkan; Donmez, SenayiIn this paper, preliminary support design of a tunnel was analyzed by numerical and empirical approaches. The case study for this analysis is a tunnel to be constructed on the Bilecik-Istanbul roadway in Turkey. The rock mass properties of the tunnel route and design support recommendations were obtained by using an empirical approach. The rock mass properties obtained from the empirical method were used as input parameters for the numerical analysis. The empirical and numerical results, in terms of support design, were evaluated. It was seen that the numerical analysis results supported by empirical values were logical and reliable.Article Citation - WoS: 3Citation - Scopus: 2Performance of a Prestressed Concrete Pedestrian Bridge System Under Equivalent Static Lateral Impact Loads(Asce-amer Soc Civil Engineers, 2013) Baran, Eray; Schultz, Arturo E.; French, Catherine E.The resistance of prestressed concrete through-girder (PCTG) pedestrian bridges to lateral loads was studied in response to the increasing number of vehicular impacts in the United States. This research was motivated by the lack of reported studies analyzing the behavior of such bridges to lateral impact loads, as well as their potential vulnerability in comparison with bridges that are better able to redistribute and transfer locally applied impact loads through alternate load paths. Pedestrian bridges are of lighter construction than highway bridges and they do not have the high degree of redundancy, making them more vulnerable to collapse in the event of vehicular impact. Results from static lateral load analyses using three-dimensional, geometrically nonlinear, full-scale finite element (FE) models of a typical bridge system and bridge subassemblages were used to evaluate the characteristics of the system. The FE models were calibrated with experimental test data on typical subassemblages and connection details for PCTG bridges. Results of the experimental part of the program have already been published elsewhere. This paper summarizes the observations obtained from nonlinear static FE analyses of a PCTG pedestrian bridge system subjected to lateral impact loads. The analyses indicated that the location of impact, the type of connector, and the flexibility of the end support details affected bridge performance. Improved connection details are suggested for enhanced PCTG pedestrian bridge performance.Article Citation - WoS: 15Citation - Scopus: 16Damage Observation of Reinforced Concrete Buildings After 2020 Sivrice (elazig) Earthquake, Turkey(Asce-amer Soc Civil Engineers, 2021) Cenan Mertol, Halit; Tunc, Gokhan; Akis, TolgaAn earthquake with a magnitude of M-w = 6.8 and a depth of approximately 8.06 km occurred on January 24, 2020, with the epicenter near the town of Sivrice in Elazig province, Turkey. The earthquake resulted in numerous collapses and severe structural damage to the buildings located in the downtowns and villages of Elazig and Malatya provinces. A technical team investigated the earthquake-affected areas, and this study presents their observations and findings with respect to reinforced concrete buildings. It was concluded that almost all of the collapsed or severely-damaged reinforced concrete buildings were constructed between 1975 and 1998. The design and construction of these buildings did not comply with the specifications of the Turkish earthquake codes valid at that time. The failures and severe damage of the buildings are associated with poor material quality, inadequate reinforcement configuration, and framing problems related to their lateral load-carrying systems. Therefore, it is recommended that buildings constructed between 1975 and 1998 in the region be structurally re-evaluated to avoid additional loss of life and property in future earthquakes. (C) 2021 American Society of Civil Engineers.
