Istanbul Airport viaduct design and seismic performance assesment

The earthquake performance of viaducts is quite important when we compared other types of structures because they should continue to give service in case of a possible earthquake. For this reason, the design of the viaducts and the evaluation of earthquake performances are important in the field of structural engineering. Within scope of this study is examine the design of viaduct. The viaduct is located where the west side connect the terminal building – and parking - building within the construction of Istanbul Airport in İstanbul. The structural analysis program SAP2000 (Structural Analysis Program) was created viaduct's three-dimensional structural system model. Using the analysis results of the model, according to AASHTO regulation was accomplished the design of structural elements of the viaduct. The XTRACT program was used for the cross-section analyzes of the viaduct elements. Based on the regulation, in addition, the earthquake performance of the viaduct was determined by using pushover analysis The general topics of the master's thesis, which consists of five chapters in total, given below. In the first part of this thesis, general information about the study, the subject and target of the study are given. In the second chapter, by the general characteristics of viaduct were mentioned and the structural elements that forms the upper and lower portion of the viaduct modeled by using SAP2000 program are given. Earthquake forces are influenced on viaduct in the transverse and longitudinal direction by taking into consider the site specific spectral acceleration values for the position Prestressed pre-fabricated girders which in the upper structure part is made load analysis, pre-stressing losses, stress analysis, bearing capacity, shear stress and deflection calculations. The other elements of the viaduct, such as pier cap, piers and foundation were checked cross-sections and required reinforcement area. In the third part, it refers about nonlinear behavior and the performance levels defined in the DLH regulation. Information about the displacement controlled incremental "equivalent earthquake load method" (static pushover analysis) from nonlinear elastic calculation methods and procedure steps to be followed in this method are summarized. In the fourth chapter, static pushover analysis is applied the pier located at the middle axis of the existing viaduct. The XTRACT program is used to material model and moment curvature diagram of the piers. Plastic hinges (plastic rotation) were obtained at the bottom end of the piers. Material deformation that can occur at the bottom end of the piers due to plastic rotations are determined under the earthquake effect with a probability of exceeding over 50 years is 10% (design earthquake) by using the spectrum coefficient values site specific to the region where the viaduct is constructed. Sectional strain was determined and compared with those of the limit values given in the DLH regulation. In the fifth chapter, with the numerical results obtained from the design and analysis are briefly given the structural safety and seismic performance of the viaduct considered is evaluated.