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Öğe Collapsed-RC Building Failure Mechanisms with a Forensic Engineering Approach(Asce-Amer Soc Civil Engineers, 2020) Etemadi, Ali; Balkaya, CanA reinforced concrete building in Konya, Turkey, collapsed suddenly on February 2, 2004, and 92 residents died. This case study was performed to determine the alternate load paths and failure mechanism of the building. The essence of a forensic engineering investigation of a construction failure is to determine the failure mechanisms by using the procedural causes and contributing factors. The building behavior under the sudden loss of ground-story columns and various scenarios of column removal was assessed. The site works and stepwise nonlinear analysis were applied to get the failure mechanism of the collapsed building. The lessons learned from this case study forensic investigation are discussed, and the construction and project errors beneath the collapse are identified. Torsion is not a desired first mode of dynamic behavior. The progressive collapse of the RC building was the torsional mode. In building due to architectural needs, i.e., lack of the beam in exterior frames, discontinuities in the three-dimensional (3D) structural framing and very low bonds existed in the RC beams, resulting in an improper redistribution of the forces. (c) 2020 American Society of Civil Engineers.Öğe Conceptual Guideway Structural Design for MAGLEV High-Speed Ground Transportation System(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2017-06-28) Balkaya, Can; Hall, W.J.The conceptual guideway structural designs for MAGLEV (magnetic-levitation) high-speed ground transportation system are discussed by considering four different guideway designs of Bechtel, Magneplane, Grumman and Foster-Miller. The important aspects of the conceptual designs as well as some of the apparent shortcomings that will need attention in the design studies are emphasized. In this context the technical assessments and design observations may be considered for the guideway conceptual designs are given in this study.Öğe Direct displacement based design of RDC frame-shear wall structures(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2021) Balkaya, Can; Etemadi, Ali; Genç, Öznur- A large part of Turkey's urban region is located in the seismic prone zone and in terms of population, the majority of densely populated cities are located close to near-fault regions. It is very important to determine the behaviors of structures againÖğe Improving Torsional Rigidity and Seismic Performance of Tunnel Form Building Structures(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2017-09-26) Balkaya, Can; Karagöz, İhsan; Günal, İsmihanTunnel form buildings, which have shear-wall dominant structural systems, are usually built in countries exposed to substantial seismic risk and very commonly used because of its fast construction technique and low cost. Very limited research has been directed to their experimental studies on 3D behavior, seismic performance, load capacities, collapse mechanisms, and crack propagations. Previous studies indicate that most of the time the first period of the structure is torsion due to construction techniques outer faces is open to take the tunnel forms to out by cranes. This will cause less torsional rigidity, whereas for strong earthquakes, torsional rigidity has to be increased. Four different strengthening techniques, i.e., steel braces, reinforced concrete (RC) infill shear wall, precast concrete shear wall, and RC shear wall at the façade, were applied to improve torsion rigidity. Experimental studies and 3D nonlinear finite element analysis (FEA) were performed on models. The analytical model results, the economy and applicability of construction techniques suggest that steel bracing is the most suitable and practical method to improve torsional rigidity as well as seismic performance. Three-story scaled existing and strengthened experimental models are tested under pushover loads, and the results are compared with 3D nonlinear finite element analysis.Öğe Information Systems for Repair Alternatives and Initial Cost Estimation of Damaged Building Structures(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2018-06-27) Balkaya, CanThe evaluation of existing structures for repair and strengthening results in the application of the most economical and effective repair techniques. The main focus is the existing buildings in seismic areas. The method of repair or strengthening depends on the damaged structural system, structural (life safety) issues, applicable seismic building code requirements, restrictions in available methods, and architectural and construction requirements. The consideration of new techniques, previous technical information on repair methods, experience of experts, and updated cost information are important in the evaluation. The most cost-effective schemes cannot be determined by choosing the most economical means to repair each component; an integrated approach is necessary. Also, recently the use of computers and networks to share the information are increasing. A knowledge-based information system has been developed for the integrated solutions. The level of damage is determined from the damage and structural information. In the evaluation, major damage conditions are grouped as ground damage, foundation damage and superstructure damage, and then these groups are divided into subgroups. Each repair method is represented by a specific format to determine the damage information index. The developed software is a self-modifying and learning system as a result of the data stored for common types of damaged buildings. The use of information systems results in rapid and effective initial cost estimation of repair methods.Öğe Investigation of Natural Frequency for Continuous Steel Bridges with Variable Cross-sections by using Finite Element Method(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2018-06-27) Sağlık, Hüseyin; Doran, Bilge; Balkaya, CanThis paper mainly focuses on the natural frequencies of steel I-girder continuous-span bridges with straight haunched sections. The finite element analysis is performed to model dynamic behaviour of bridges by using CSIBridge package. Continuous-span bridges (two to six) with straight haunched section are considered. All the dimensions used for generating bridge models are designed according to AASHTO LRFD Standards. Effect of various parameters such as span length, the depth ratios between haunched cross-section to mid-span cross-section (r), the length ratio between haunched section to span (?), span configuration and steel girder arrangement on natural frequencies are investigated by numerically generating one hundred fifty three bridge models. “r” and “?” values are set to be 0.5 - 2.0 and 0.1 - 0.5. The analysis results are given and discussed for the natural frequency of continuous-span composite steel bridges with straight haunched section.Öğe Lessons Learned from Collapse of Zumrut Building under Gravity Loads(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2017-06-28) Balkaya, CanThe 11-story reinforced concrete Zumrut Building in Konya, Turkey collapsed on February 2, 2004. Ninety-two people died. This study was conducted to determine the mechanism of the collapse and identify lessons learned to avoid future disasters. Using structural drawings, material samples, and soil information obtained from the site, reasons for the collapse were investigated. A three-dimensional (3-D) structural model and analyses were performed using ETABSV8.11, and various possible critical cases were studied. The step-wise nonlinear analysis used to obtain the collapse mechanisms was an example of forensic structural engineering and revealed that the progressive collapse of the building was torsional, caused by decrease in structural system’s capacity to redistribute gravity load after failure of a column. The lessons learned include the importance of project controls to reduce design and construction errors, ensure that construction and repairs are consistent with design intent, and changes are checked for safety and included in drawings. The importance of integrating architectural and structural systems to form 3-D continous structural frames to reduce the probability of progressive collapse is also discussed.Öğe Nonlinear Integrated Design of Lattice Domes with Supporting Substructures(İstanbul Gelişim Üniversitesi Yayınları / Istanbul Gelisim University Press, 2017-08-26) Etemadi, Ali; Balkaya, CanThis paper investigates the response interaction between reinforced concrete substructure and steel raised lattice roofing. The viewpoint of dynamic stability and nonlinear seismic behavior are considered as both geometrical and material nonlinearity. In particularly, dynamic stability performance of single layer Diamatic domes located on peripheral reinforced concrete columns is investigated under vertical loads and seismic excitation. Different supporting structures with rigidity and reinforcement detailing of the circular peripheral columns are considered in the integrated design. The vibration modes for the lattice dome with and without substructure effects are studied. Results show that high capacity substructure or fixed supporting assumption may lead to unsafe stability performance as well as uneconomical designs. The integrated design of composite system, RC supporting substructure and upper lattice roof could be provided superior dynamic stability performance when compared to the design without supporting substructure.
