assessed and strengthened. Performance evaluation of deficient buildings has become a major concern due to devastating earthquakes in the past. In order to justify new provisions in design and assessment codes, experiments and analyses are inherently necessary. In this thesis study, investigations into the behaviour of two deficient reinforced concrete frames built at Middle East Technical University&rsquo / s Structural and Earthquake Laboratory and tested via pseudo-dynamic tests were made. These frames were modelled on the OpenSees platform by following methods of analyses outlined in the Turkish Earthquake Code of 2007 (TEC 2007) and ASCE/SEI-41-06. Both deficient frames were essentially the same, with the only difference being the presence of insufficient lap splices, which was the focus of the study. Time history performance assessments were conducted in accordance to TEC 2007&rsquo / s damage state limits and ASCE/SEI 41-06&rsquo / s performance limits. The damages observed matched the performance levels estimated through the procedure outlined in TEC 2007 rather well. Specific to the specimen with lap splice deficiencies, ASCE/SEI 41-06 was overly conservative in its assessments. TEC 2007&rsquo / s requirements for lap splice lengths were found to be conservative in the laboratory and are able to tolerate deficiencies up to 25% of the required length. With respect to mathematical models, accounting for materials in deficient systems by using nominal but reduced strength properties is not very efficient and unless joint deformations are explicitly accounted for, local deformations cannot be captured.

Contemporary approach performance based engineering generally relies on the approximate procedures that are based on the use of capacity curve derived from pushover analysis. The most important parameter in the displacement-based approach is the inelastic displacement demand computed under a given seismic effect and the most common procedures employed for this estimation / the Capacity Spectrum Method and the Displacement Coefficient Method are based on bi-linearization of the capacity curve. Although there are some recommendations for this approximation, there is a vital need for rational guidelines towards the selection of the most appropriate method among several alternatives. A comprehensive research has been undertaken to evaluate the influence of several existing alternatives used for approximating the capacity curve on seismic demands. A number of frames were analyzed under a set of 100 ground motions employing OpenSees. In addition, the pushover curves obtained from nonlinear static analyses were approximated using several alternatives and the resulting curves were assigned as the force-deformation relationships of corresponding equivalent single-degree-of-freedom systems. These simplified systems were later analyzed to compute the approximate seismic response parameters. Using the results of the complex and simplified analyses, the performance of each approximation method was evaluated in estimating the &amp / #8216 / exact&amp / #8217 / inelastic deformations of the multi-degree-of-freedom systems at various degrees of inelasticity. Dependency of the errors on ductility, strength reduction factor and period was also investigated. The interpretations made and the conclusions drawn in this study is believed to clarify the rationality and accuracy of selecting the appropriate idealization of the capacity curve.

In this study steel framing systems are investigated with regards to their lateral load carrying capacity and in this context seismic response modification factors of individual systems are analyzed. Numerous load resisting layouts, such as different bracing systems and un-braced moment resisting frames with various bay and story configurations are designed and evaluated in a parametric fashion. Three types of beam to column connection conditions are incorporated in evaluation process. Frames, designed according to Turkish seismic code, are investigated by nonlinear static analysis with the guidance of previous studies and recent provisions of FEMA. Method of analysis, design and evaluation data are presented in detail. Previous studies in literature, history and the theory of response modification phenomenon is presented. Results are summarized, main weaknesses and ambiguities introduced to design by the use of &ldquo / R&rdquo / factors are stated depending on the observed behavior.

Curved bridges with steel/concrete composite girders are used frequently in the recent years. Analysis of these structural systems presents a variety of challenges. Finite element method offers the most elaborate treatment for these systems, however its use is limited in routine design practice due to modeling requirements. In recent years, a finite element program named UTrAp was developed to analyze construction stages of curved/straight composite bridges. The original Graphical User Interface could not be used with the modified computation engine. It is the focus of this thesis work to develop a brand new Graphical User Interface with enhanced visual capabilities compatible with the engine. Pursuant to this goal a Graphical User Interface was developed using C++ programming language together with OPENGL libraries. The interface is linked to the computational engine to enable direct interaction between two programs. In the following thesis work the development of the GUI and the modifications to the computational engine are presented. Moreover, the analysis results pertaining to the newly added features are checked against analytical solutions and recommendations presented in design specifications.

Investigation of more than seventy highway bridges revealed that multisimple-span skew bridges with expansion joints were very common in Turkish practice. The expansion joints, used to provide deck expansion against shrinkage, creep and thermal effects, create costly maintenance problems due to leaked water, impact loads and accumulated debris in the joints. Therefore, elimination of expansion joints decreases the maintenance cost for the bridges. Reinforced concrete link slabs provide continuity at the deck level with the elimination of expansion joints. This thesis focuses on evaluating the seismic behavior of the skew multisimple-span bridges in Turkey and also discusses the use of reinforced concrete link slabs as a seismic retrofit option. The effects of addition of link slab and varying skew angle on the performance of the bridges were investigated. The use of link slabs can provide a better seismic displacement control, can decrease the member forces and can prevent or reduce deterioration of the top of the piers and ends of the girders from the water and chemical leakage by abandoning or minimizing number of expansion joints.

Minimum requirements for lap splices in reinforced concrete members, stated in building codes of TS-500 and ACI-318, have a certain factor of safety. These standards have been prepared according to research results conducted previously and they are being updated according to results of recent studies. However the reliability of lap splices for minimum requirements needs to be investigated. For this purpose, 6 beam specimens were prepared according to minimum provisions of these standards. The test results were investigated by analytical procedures and also a parametric study was done to compare two standards. For smaller diameter bars both standards give safe results. Results showed that the minimum clear cover given in TS500 is insufficient for lap spliced bars greater than or equal to 26 mm diameter.

Bracing members are considered to be effective earthquake-resistant elements as they improve the lateral strength and stiffness of the structural system and contribute to seismic energy dissipation by deforming inelastically during severe earthquake motions. However, the cyclic behavior of such bracing members is quite complex because it is influenced by both buckling and yielding. This thesis presents simple but an efficient analytical model that can be used to simulate the inelastic cyclic behavior of steel braces. This model achieves realism and efficiency by combining analytical formulations with some semi-empirical formulas developed on the basis of a study of experimental data. A brace is idealized as a pin-pin ended member with a plastic hinge located at mid-length of a brace Input parameters of the model are based on only material properties such as steel yield strength and modulus of elasticity as well as geometric properties including cross-sectional area, moment of inertia, etc. The obtained results are verified by the experimental and available analytical results.

A comprehensive study has been carried out to investigate the correlation between deformation demands of frame structures and a number of widely cited ground motion intensity parameters. Nonlinear response history analyses of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) models derived from sixteen reinforced concrete frames were carried out under a set of eighty ground motion records. The frames were selected to portray features of typical low-to-mid rise reinforced concrete structures. The records contained in the ground motion database were compiled from the recorded ground motions with the intention to possess a broad range of amplitude, frequency content and duration characteristics that shift selected frames into various degrees of elastic as well as inelastic response. Maximum deformation demands of SDOF models and the maximum interstory drift ratios of MDOF models, response parameters of interest, were computed employing 1280 nonlinear response history analyses. Computed response parameters were compared with the ground motion intensity parameters employed and correlation between them were quantified through coefficients of correlation and determination. The results revealed that the spectral intensity parameters including spectral amplitudes over a range of period covering the frame structures have the strongest correlation and present better relationship with the deformation demands compared to the intensity parameters that are based on a single amplitude such as PGA, PGV and spectral acceleration. Besides analytical study, association of ground motion parameters with observed damage has been investigated and no clear trend has been observed between the performance of the buildings and the seismic indices.

This thesis work deals with manufacturing a lightweight composite unmanned aerial vehicle (UAV) wing, material characterization of the composites used in the UAV wing, and preliminary structural analysis of the UAV wing. Manufacturing is performed at the composite laboratory founded in the Department of Aerospace Engineering, and with hand lay-up and vacuum bagging method at room temperature the wing is produced. This study encloses the detailed manufacturing process of the UAV wing from the mold manufacturing up to the final wing configuration supported with sketches and pictures. Structural analysis of the composite wing performed in this study is based on the material properties determined by coupon tests and micromechanics approaches. Contrary to the metallic materials, the actual material properties of composites are generally not available in the material handbooks, because the elastic properties of composite materials are dependent on the manufacturing process. In this study, the mechanical properties, i.e. Young&rsquo / s Modulus, are determined utilizing three different methods. Firstly, longitudinal tensile testing of the coupon specimens is performed to obtain the elastic properties. Secondly, mechanics of materials approach is used to determine the elastic properties. Additionally, an approximate method, that can be used in a preliminary study, is employed. The elastic properties determined by the tests and other approaches are compared to each other. One of the aims of this study is to establish an equivalent material model based on test and micromechanics approach, and use the equivalent model in the structural analysis by finite element method. To achieve this, composite structure of the wing is modeled in detail with full composite material descriptions of the surfaces of the wing structure, and comparisons are made with the results obtained by utilizing equivalent elastic constants. The analyses revealed that all three approaches have consistent, and close results / especially in terms of deflections and natural frequencies. Stress values obtained are also comparable as well. For a case study on level flight conditions, spanwise wing loading distribution is obtained using a program of ESDU, and the wing is analyzed with the distributed loading. Reasonable results are obtained, and the results compared with the tip loading case. Another issue dealt in this study is analyzing the front spar of the wing separately. The analysis of the front spar is performed using transformed section method and finite element analysis. In the results, it is found that both methods calculates the deflections very close to each other. Close stress results are found when solid elements are used in the finite element analysis, whereas, the results were deviating when shell elements are used in the analysis.

In this study, seismic roof isolation solutions were investigated with a case study of Halkapinar Gymnasium, izmir. In the first part, seismic isolation was explanied and philosophy behind it was given. In the second part, existing seismic roof isolators, elastomeric bearing and viscous damper, were investigated with different support isolation combinations. In the third part, two more types of seismic isolators, lead rubber bearing and friction pendulum isolators, were also analyzed by using the same model and all results were compared with each other and that of non-isolated roof system. Furthermore, bilinear effect of the non-linear isolators were also studied. Finally, all results were compared with each other considering structure responses and effectiveness of the seismic isolators. It has been tried to find the most efficient seismic isolation solution for Halkapinar Gymnasium.