The performance of reinforced concrete (RC) columns during recent earthquakes has clearly demonstrated the possible failures associated with inadequate confining reinforcement. The confinement reinforcement requirements of older codes were less stringent than present standards. Many studies were conducted by applying different retrofitting techniques for RC columns that have inadequate confinement reinforcement. A new retrofitting technique by means of Carbon Fiber Reinforced Polymer (CFRP) was developed and tested in many countries in the last decade. This technique is performed by CFRP wrapping the critical region of columns. The effectiveness of CFRP retrofitting technique was shown in many studies conducted worldwide. In Turkey, the frame members are considerably deficient from the seismic detailing point of view. Therefore, in order to use the CFRP retrofitting technique effectively in Turkey, experimental evidence is needed. This study investigates the performance of CFRP retrofitted RC columns with deficient confining steel and low concrete strength. It was concluded by experimental and analytical results that the CFRP retrofitting method can be implemented to seismically deficient columns. Moreover, two design approaches were proposed for CFRP retrofit design of columns considering safe design regulations.

An analytical study was performed to evaluate the effect of shear wall ratio on the dynamic behavior of mid-rise reinforced concrete structures. The primary aim of this study is to examine the influence of shear wall area to floor area ratio on the dynamic performance of a building. Besides, the effect of shear wall configuration and area of existing columns on the seismic performance of the buildings were also investigated. For this purpose, twenty four mid-rise building models that have five and eight stories and shear wall ratios ranging between 0.51 and 2.17 percent in both directions were generated. These building models were examined by carrying out nonlinear time-history analyses using PERFORM 3D. The analytical model used in this study was verified by comparing the analytical results with the experimental results of a full-scale seven-story reinforced concrete shear wall building that was tested for U.S.-Japan Cooperative Research Program in 1981. In the analyses, seven different ground motion time histories were used and obtained data was averaged and utilized in the evaluation of the seismic performance. Main parameters affecting the overall performance were taken as roof and interstory drifts, their distribution throughout the structure and the base shear characteristics. The analytical results indicated that at least 1.0 percent shear wall ratio should be provided in the design of mid-rise buildings, in order to control observed drift. In addition / when the shear wall ratio increased beyond 1.5 percent, it was observed that the improvement of the seismic performance is not as significant.

Turkey is located on a seismically active region. Heavy damage observed in school buildings during recent earthquakes, revealed that seismic performance of school buildings is considerably poor. Therefore, determination of seismic vulnerability of these buildings has gained significant attention. Capacity curves that reflect properties of buildings are used to determine the seismic demand, thus, a decision can be made about the expected performance of the buildings. In addition, seismic vulnerability assessment procedures are also developed to assess the expected performance of buildings. In this study, it was intended to determine capacity related properties of school buildings located in Turkey. Additionally, applicability of some existing seismic vulnerability assessment procedures for school buildings is investigated. The procedures developed by Yakut [3], Hassan &amp / Sozen [8] and Ozcebe et al. [10] were employed. For this purpose, a set of school buildings that are believed to represent typical cases were employed. Nonlinear static analysis was carried out to determine the capacity related properties and approximate seismic demand. All buildings were assessed using the available preliminary seismic assessment procedures and the results were compared with detailed assessment procedures.

Simplified methods of analysis described in codes and specifications for seismically isolated structures are always used either directly in special cases or for checking the results of nonlinear response history analysis (RHA). Important predictions for seismically isolated structures by simplified methods are the maximum displacements and base shears of the isolation system. In this study, the maximum isolator displacements and base shears determined by nonlinear RHA are compared with those determined by the equivalent lateral force (ELF) procedure in order to assess the accuracy of the simplified method in the case of bi-directional excitations with near-field characteristics. However, although there are currently many methods for ground motion selection and scaling, little guidance is available to classify which method is more appropriate than the others in any applications. Features of this study are that the ground motions used in analysis are selected and scaled using contemporary concepts and that the ground excitation is considered biv directional. The variations in response of isolated structures due to application of ground motions uni-directionally and bi-directionally are also studied by employing a scaling procedure that is appropriate for the bi-directional analysis. The proposed new scaling methodology is an amplitude scaling method that is capable of preserving the horizontal orthogonal components and it is developed especially for dynamic analysis of isolated structures. Analyses are conducted for two different symmetric reinforced concrete isolated structure for two different soil conditions in structural analysis program SAP2000. Effect of asymmetry in superstructure on isolator displacement is also investigated with further analyses considering 5% mass eccentricity at each floor level. Furthermore, once the significance of the orthogonal horizontal component on the response of isolation system is shown, the biaxial interaction of hysteretic behavior of lead rubber bearings is implemented in OpenSees by developing a subroutine which was not readily available.

Assessment of potential ground motions in seismically active regions is essential for purposes of seismic design and analysis. Peak ground motion intensity values and frequency content of seismic excitations are required for reliable seismic design, analysis and retrofitting of structures. In regions of sparse or no strong ground motion records, ground motion simulations provide physics-based synthetic records. These simulations provide not only the earthquake engineering parameters but also give insight into the mechanisms of the earthquakes. This thesis presents strong ground motion simulations in three regions of intense seismic activity. Stochastic finite-fault simulation methodology with a dynamic corner frequency approach is applied to three case studies performed in D&uuml / zce, L&rsquo / Aquila and Erzincan regions. In D&uuml / zce study, regional seismic source, propagation and site parameters are determined through validation of the simulations against the records. In L&rsquo / Aquila case study, in addition to study of the regional parameters, the limitations of the method in terms of simulating the directivity effects are also investigated. In Erzincan case study, where there are very few records, the optimum model parameters are determined using a large set of simulations with an error-minimization scheme. Later, a parametric sensitivity study is performed to observe the variations in simulation results to small perturbations in input parameters. Results of this study confirm that stochastic finite-fault simulation method is an effective technique for generating realistic physics-based synthetic records of large earthquakes in near field regions.

There are many advantages of masonry construction like widespread geographic availability in many forms, colors and textures, comparative cheapness, fire resistance, thermal and sound insulation, durability, etc. For such reasons, it is still a commonly used type of residential construction in rural and even in urban regions. Unfortunately, its behavior especially under the effect of earthquake ground motions has not been identified clearly because of its complex material nature. Hence, the masonry buildings with structural deficiencies belong to the most vulnerable class of structures which have experienced heavy damage or even total collapse in previous earthquakes, especially in developing countries like Turkey. This necessitates new contemporary methods for designing safer masonry structures or assessing their performance. Considering all these facts, this study aims at the generation of a new performance-based technique for unreinforced brick masonry structures. First, simplified formulations are recommended to estimate idealized capacity curve parameters of masonry components (piers) by using the finite element analysis results of ANSYS and regression analysis through SPSS software. Local limit states for individual masonry piers are also obtained. Then, by combining the component behavior, lateral capacity curve of the masonry building is constructed together with the global limit states. The final step is to define seismic demand of the design earthquake from the building through TEC2007 method. By using this simple technique, a large population of masonry buildings can be examined in a relatively short period of time noting that the performance estimations are quite reliable since they are based on sophisticated finite element analysis results.

Due to their practical application, flat-plates have been commonly used slab type in constructions in recent years. According to the investigations that were performed since the beginning of the 20th century, the vicinity of the slab-column connection is found to be susceptible to punching failure that causes serious unrepairable damage leading to the collapse of the structures. The objective of this study is to enhance the punching shear strength of slab-column connections in existing deficient flat plate structures. For this purpose, an economical and easy to install strengthening method was applied to &frac34 / scale flat-slab test specimens. The proposed strengthening scheme employs the use of in house-fabricated Carbon Fiber Reinforced Polymer (CFRP) dowels placed around the column stubs in different numbers and arrangements as vertical shear reinforcement. In addition, the effect of column aspect ratio on strengthening method was also investigated in the scope of this study. Strength increase of at least 30% was obtained for the CFRP retrofitted specimens compared to the companion reference specimen. Three-dimensional finite element analyses of test specimens were conducted by using the general purpose finite element analyses program. 3-D finite element models are successful in providing reasonable estimates of load-deformation behavior and strains. The experimental punching shear capacities and observed failure modes of the specimens were compared with the estimations of strength and failure modes given by punching shear strength provisions of ACI 318-08, Eurocode-2, BS8110-97 and TS500. Necessary modifications were proposed for the existing provisions of punching shear capacity in order to design CFRP upgrading.

This thesis examines the seismic internal retrofitting of existing deficient reinforced concrete (RC) structures by using structural steel members. Both experimental and numerical studies were performed. The strengthening methods utilized with the scope of this work are chevron braces, internal steel frames (ISFs), X-braces and column with shear plate. For this purpose, thirteen strengthened and two as built reference one bay one story portal frame specimens having 1/3 scales were tested under constant gravity load and increasing cyclic lateral displacement excursions. In addition, two &frac12 / scaled three bay-two story frame specimens strengthened with chevron brace and ISF were tested by employing continuous pseudo dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace and column with shear plate assemblage technique were unsatisfactory. On the other hand, both chevron brace and ISF had acceptable cyclic performance and these two techniques were found to be candidate solutions for seismic retrofitting of deficient RC structures. The numerical simulations by conducting nonlinear static and dynamic analysis were used to estimate performance limits of the RC frame and steel members. Suggested strengthening approaches, chevron brace and ISF, were also employed to an existing five story case study RC building to demonstrate the performance efficiency. Finally, design approaches by using existing strengthening guidelines in Turkish Earthquake Code and ASCE/SEI 41 (2007) documents were suggested.

Future seismic losses including the physical, economic and social ones as well as casualties concern a wide range of authorities varying from geophysical and earthquake engineers, physical and economic planners to insurance companies. As its many components involve inherent uncertainties, a probabilistic approach is required to estimate seismic losses. This study aims to propose a probabilistic method for estimating seismic losses, and to predict the potential seismic loss for the residential buildings for a selected district in Bursa, which is a highly industrialized city in Northwestern Turkey. To verify the methodology against a past large event, loss estimations are initially performed for a district in D&uuml / zce, and the method is calibrated with loss data from the 12 November 1999 D&uuml / zce Earthquake. The main components of the proposed loss model are seismic hazard, building vulnerability functions and loss as a function of damage states of buildings. To quantify the regional hazard, a probabilistic seismic hazard assessment approach is adopted. For different types of building structures, probability of exceeding predefined damage states for a given hazard level is determined using appropriate fragility curve sets. The casualty model for a given damage level considers the occupancy type, population of the building, occupancy at the time of earthquake occurrence, number of trapped occupants in the collapse, injury distribution at collapse and mortality post collapse. Economic loss is calculated by multiplying mean damage ratio with the total cost of initial construction. The proposed loss model combines these input components within a conditional probability approach. The results are expressed in terms of expected loss and losses caused by events with different return periods.

The purpose of this thesis is to investigate the inelastic action in the reinforced concrete frame-wall structures analytically and with that analysis to follow the plastic formation of the structure. For this purpose, six mid-rise reinforced concrete buildings with frame-wall are modeled and analyzed to understand the effect of the height and base shear force ratio of the wall on the nonlinear interaction between reinforced concrete wall and frame members under static lateral loads and ground motion excitations. The parametric analysis is conducted by assuming planar response of the buildings under loadings. The buildings are generated considering the limit design concept suggested by Turkish Earthquake Code 2007 and Turkish Standards TS500, and the frame-wall members are modeled by using spread plasticity elements and fiber discretization of sections. In the analysis stage, each element section is divided into confined and unconfined regions for detailed modeling of the building by using OpenSEES nonlinear finite element program. Two dimensional analyses are conducted under static and dynamic loadings. For static pushover analyses, three different lateral load cases (Triangular, Uniform and First-Mode Lateral Load Patterns) are considered. For dynamic analyses, eight different ground motions are used. These ground motions are scaled to the corresponding design response spectrum suggested by Turkish Earthquake Code 2007 by using RSPMATCH program. Using the result of the complex and simplified analyses, inter-story drift ratios, plastic rotations and internal force distributions of the buildings are investigated.