Bridge design should take into account not only safety and functionality, but also the cost effectiveness of investments throughout a bridge life-cycle. This work presents a probabilistic approach to compute the life-cycle cost (LCC) of corroding reinforced concrete (RC) bridges in earthquake prone regions. The approach is developed by combining cumulative seismic damage and damage associated to corrosion due to environmental conditions. Cumulative seismic damage is obtained from a low-cycle fatigue analysis. Chloride-induced corrosion of steel reinforcement is computed based on Fick’s second law of diffusion. The proposed methodology accounts for the uncertainties in the ground motion parameters, the distance from source, the seismic demand on the bridge, and the corrosion initiation time. The statistics of the accumulated damage and the cost of repairs throughout the bridge life-cycle are obtained by Monte-Carlo simulation. As an illustration of the proposed approach, the effect of design parameters on the life-cycle cost of an example RC bridge is studied. The results are shown to be valuable in better estimating the condition of existing bridges (i.e., total accumulated damage at any given time) and, therefore, can help schedule inspection and maintenance programs. In addition, by taking into consideration the deterioration process over a bridge life-cycle, it is possible to make an estimate of the optimum design parameters by minimizing, for example, the expected cost throughout the life of the structure.

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.

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.

Reinforced concrete structures may be subjected to blast loads together with static loads during their service life. Important buildings may be attacked by using explosives as a part of increasing global terrorist activities. Evaluation of blast phenomena for economically and strategically significant buildings is especially important, in order to analyze and design their structural members subjected to air blast loading. Understanding nature of explosions, which are loading characteristics and relation to selected parameters such as explosive type, quantity, and distance, were studied in this thesis. Earlier studies found in the literature survey on explosives, blast, and behavior of structural elements were investigated. Behavior of structures under blast load was described in terms of pressure magnitude, distribution, and reflection phenomena. Simple design, assessment guidelines, and useful charts were developed. A computer program was generated using MATLAB programming language, which automatically generates the air blast pressure versus time data resulting from an air explosion in addition to finite element model formation and dynamic time stepping analysis of a reinforced concrete column. The shear and moment capacities can be calculated and compared against dynamically calculated demand under known axial column force / therefore, vulnerability of a column under blast loading is evaluated. The results of the numerical analyses indicated that failure mechanism of columns is mostly shear failure instead of moment (i.e., plastic hinge and mechanism formation).

The aim of this thesis is to demonstrate that it is possible to design earthquake resistant residential structures without significant compromises in the spatial quality and economic viability of the building. The specific type of structural system that this thesis focuses on is the reinforced concrete skeleton system. The parametric examples and key studies that are used in this research are chosen among applied projects in the city of Bolu. This city is chosen due to its location on the North Anatolian Fault and its destructive seismic history. The structural validity of the hypothesis was demonstrated through an analytical process during which a set of 7 models were tested. 5 of these were designed as idealized parametric models and 2 of them were based on actual buildings destroyed in earthquakes. The architectural validity of the hypothesis was demonstrated on a set of 3 architectural projects. Projects were subjected to a comparative evaluation between their original states and the modified seismically resistant versions. The architectural comparison between earthquake resistant and non-resistant states was made on a planimetric basis. Comparison parameters were: floor area / size, location and number of rooms / and access to view. The feasibility of seismically resistant reinforced concrete residential buildings was demonstrated through an approximate cost analysis which has proven that designing earthquake resistant structures only resulted in an acceptable 4-8 percent rise in the overall building cost.

Structures in high seismic risk areas may be susceptible to severe damage in a major earthquake. Structures designed to meet older code requirements may be at even greater risk. When these structures are evaluated with respect to current code criteria, it is observed that they lack of lateral strength and/or ductility. Since safety and economic considerations are major problems, these structures become viable candidates for retrofit and seismic strengthening. For the variety of structures and possible deficiencies that arise, several retrofitting techniques can be considered. Diagonal bracing system is one of the retrofitting techniques and it provides an excellent approach for strengthening and stiffening existing building for lateral forces. Also, another potential advantage of this system is the comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques. In this study, the use of steel bracing for the strengthening of low, intermediate, and relatively high rise reinforced concrete frames are investigated analytically. The ultimate lateral load capacities of the strengthened frames are determined by a load controlled push-over analysis. The post-tensioning effect of preloading is also investigated.

Non-ductile reinforced concrete frame buildings constitute an important part of the vulnerable buildings in seismic regions of the world. Collapse of non-ductile multi story concrete buildings during strong earthquakes in the past resulted in severe casualties and economic losses. Their rehabilitation through retrofitting is a critical issue in reducing seismic risks worldwide. A displacement-based retrofitting approach is presented in this study for seismic retrofitting of medium height non-ductile concrete frames. A minimum amount of shear walls are added for maintaining the deformation levels below the critical level dictated by the existing columns in the critical story, which is usually at the ground story. Detailing of shear walls are based on conforming to the reduced deformation demands of the retrofitted frame/wall system. Member-end rotations are employed as the response parameters for performance evaluation. Initial results obtained from the proposed displacement based approach have revealed that jacketing of columns and confining the end regions of added shear walls are usually unnecessary compared to the conventional force-based approach, where excessive force and deformation capacities are provided regardless of the actual deformation demands.

There is a large building stock in seismic regions of Turkey that require seismic upgrades. In order to minimize the disturbance to occupants and not to intervene with the functioning of the building, external strengthening methods can be preferred among different alternatives. This study reports the experimental findings on the upgrading of deficient reinforced concrete frames with external installed structural components. Specimens strengthened with an externally reinforced concrete shear wall, external steel frames, steel plate shear wall and one as-built reference 1/3-scale portal frame specimens were tested under constant gravity load and increasing cyclic displacement excursions. The RC frames had deficiencies those mimic the existing deficient building stock in Turkey. The test results showed that the external upgrading can increase both the lateral stiffness and strength of deficient RC frames considerably. Finite element analyses were conducted to specimen models to investigate the behaviors numerically. Furthermore, corresponding single degree of freedom (SDOF) models of specimens were generated to perform dynamic analysis. Results show the importance of hysteretic response and enhancement of energy dissipation capability with drift control.

Reinforced concrete frame buildings are the most common type of constructions in Turkey which are exposed to various types of forces during their lifetime. Seismic performance of reinforced concrete frame buildings is dominated by columns which can be classified as primary members of these structures. When current codes are considered, all of them contain several provisions in order to implement reliable seismic performances of reinforced concrete columns. In order to evaluate the accuracy of these provisions, analytical and parametric studies are carried out for flexure critical reinforced concrete columns. In these studies, total numbers of 30 flexure critical columns are extracted from PEER database (2005) and analytically investigated. Once the seismic responses obtained from analytical investigations are close enough to experimental seismic responses, performance based displacement limits are pointed out according to TEC (2007), FEMA 356 (2000), Eurocode 8 (2003), and ASCE/SEI 41 Update (2009). In addition to this, total numbers of 144 flexure critical columns are generated in parametric studies to present the effects of various parameters such as column geometry, concrete strength, axial load ratio, transverse reinforcement ratio, and yielding strength of longitudinal reinforcement on performance based displacement limits. Performance based displacement limits proposed by TEC (2007), FEMA 356 (2000), Eurocode 8 (2003), and ASCE/SEI 41 Update (2009) are found very conservative compared to limits obtained from both experimental and analytical behavior. On the other hand, performance based displacement limits given in Eurocode 8 (2003) and ASCE/SEI 41 Update (2009) predict the experimental behavior more accurate than TEC (2007) and FEMA 356 (2000). Improvements on these limits are proposed.

Ziel der Arbeiten ist die Entwicklung von Verbindungsgeometrien für ebene, textilbewehrte Betonbauteile auf Basis der Klebtechnik. Zur Charakterisierung des Tragverhaltens geeigneter Verbindungen werden umfangreiche experimentelle Verbunduntersuchungen auf Garn- und Bauteilebene durchgeführt. Mit den so gestalteten Verbindungen mit nachträglichem Verguss lassen sich die Referenzlasten des ungestörten Bauteils erreichen, wobei eine weitere Optimierung der Klebung zur Gewährleistung einer vereinfachten Herstellbarkeit und eines reproduzierbaren Versagensverhaltens anzustreben ist.