Located on one of the highly active seismic fault systems in the world, the building stock in Turkey is mainly composed of reinforced concrete frames with 4-5 stories. Due to design and construction deficiencies resulting from the use of unqualified personnel and insufficient supervision, many of these buildings lack lateral stiffness, ductility and strength. For many structures, there is a need to alleviate these deficiencies by means of some rehabilitation techniques prior to earthquakes. One approach also used very widely in Turkey is to fill some of the frame bays by cast-in-place R/C panels. The procedure appears to be very practical at first glance. It also appears to be very economical as far as the production of the panels is concerned. However, the production phase is slow, dirty, destructive and disruptive to occupants. Moreover, it requires relatively skilled personnel and special equipment. Therefore, the real life experience shows that the actual cost in practice is much higher when all other hidden costs are taken into account. The aim of this experimental study is to explore the potential of using infill walls made of custom shaped and high strength concrete blocks as a simpler and more practical alternative to cast-in-place R/C panels to increase the lateral load bearing capacity of frame structures. The effectiveness of FRCM (Fiber Reinforced Cementitous Matrix) system on damaged structures is also investigated in this study.

An analytical study was carried out to evaluate shear wall indexes for low to mid-rise reinforced concrete structures. The aim of this study was to evaluate the effect of different shear wall ratios on performance of buildings to be utilized in the preliminary assessment and design stages of reinforced concrete buildings with shear walls. In order to achieve this aim, forty five 3D building models with two, five and eight storeys having different wall ratios were generated. Linearly elastic and nonlinear static pushover analyses of the models were performed by SAP2000. Variation of roof drift and interstorey drift with shear wall ratio was obtained and results were compared with the results of approximate procedures in the literature. Additionally, performance evaluation of building models was carried out according to the linearly elastic method of Turkish Earthquake Code 2007 with Probina Orion. According to the results of the analysis, it was concluded that drift is generally not the primary concern for low to mid-rise buildings with shear walls. A direct relationship could not be established between wall index and code performance criteria. However, approximate limits for wall indexes that can be used in the preliminary design and assessment stages of buildings were proposed for different performance levels.

The main objective of the thesis is evaluating and comparing Second-Order Elastic Analysis Methods defined in two different specifications, AISC 2005 and TS648 (1980). There are many theoretical approaches that can provide exact solution for the problem. However, approximate methods are still needed for design purposes. Simple formulations for code applications were developed, and they are valid as acceptable results can be obtained within admissible error limits. Within the content of the thesis, firstly background information related to second-order effects will be presented. The emphasis will be on the definition of geometric non-linearity, also called as P-&amp / #948 / and P-&amp / #916 / effects. In addition, the approximate methods defined in AISC 2005 (B1 &ndash / B2 Method), and TS648 (1980) will be discussed in detail. Then, example problems will be solved for the demonstration of theoretical formulations for members with and without end translation cases. Also, the results obtained from the structural analysis software, SAP2000, will be compared with the results acquired from the exact and the approximate methods. Finally, conclusions related to the study will be stated.

In an effort to achieve lighter and more economical space structures, a new patented steel composite member has been suggested and used in the construction of some steel roof structures. This special element has a sandwich construction composed of some strips of steel plates placed longitudinally along a helical wire core. The function of the helical core is to transfer the shear between the flange plates and increase the sectional inertia of the resulting composite member by keeping the flange plates at a desired distance from each other. Because of the lack of research, design engineers usually treat such elements as a solid member as if it has a full shear transfer between the flanges. However, a detailed analysis shows that this is not a valid assumption and leads to very unsafe results. In this context, the purpose of this study is to investigate the behavior of such members under axial compression and determine their effective sectional flexural rigidity by taking into account the shear deformations. This study applies an analytical investigation to a specific form of such elements with four flange plates placed symmetrically around a helical wire core. Five independent parameters of such a member are selected for this purpose. These are the spiral core and core wire diameters, the pitch of the spiral core, and the flange plate dimensions. Elements with varying combinations of the selected parameters are first analyzed in detail by finite element method, and some design charts are generated for the determination of the effective sectional properties to be used in the structural analysis and the buckling loads. For this purpose, an alternative closed-form approximate analytical solution is also suggested.

Design recommendations for steel plate shear wall (SPSW) systems have recently been introduced into seismic provisions for steel buildings. Response modification, overstrength, and displacement amplification factors for SPSW systems presented in the design codes were based on professional experience and judgment. A numerical study has been undertaken to evaluate these factors for SPSW systems. Forty four unstiffened SPSWs possessing different geometrical characteristics were designed based on the recommendations given in the AISC Seismic Provisions. Bay width, number of stories, story mass, and steel plate thickness were considered as the prime variables that influence the response. Twenty records were selected to include the variability in ground motion characteristics. In order to provide a detailed analysis of the post-buckling response, three-dimensional finite element analyses were conducted for the 44 structures subjected to the selected suite of earthquake records. For each structure and earthquake record two analyses were conducted in which the first one includes geometrical nonlinearities and the other one includes both geometrical and material nonlinearities, resulting in a total of 1760 time history analysis. In this thesis, the details of the design and analysis methodology are given. Based on the analysis results response modification, overstrength and displacement amplification factors for SPSW systems are evaluated.

Prior studies indicated that beam-to-column connections of reinforced concrete (RC) moment resisting frame structures experience considerable deformations under earthquake loading and these deformations have a major contribution to story drift of the building. In current analysis and design applications, however, the connection regions are generally modeled as rigid zones and the inelastic behavior of the joint is not taken into account. This assumption gives rise to an underestimation of the story drifts and hence to an improper assessment of the seismic performance of the structure. In order to implement the effect of these regions into the seismic design and analysis of buildings, a model that properly represents the seismic behavior of connection regions needs to be developed. In this study, a parametric model which predicts the joint shear strength versus strain relationship is generated by investigating the several prior experimental studies on RC beam-to-column connections subjected to cyclic loading and establishing an extensive database. Considering previous experimental research and employing statistical correlation method, parameters that significantly influence the joint behavior are determined and these parameters are combined together to form a joint model. This model is then verified by comparing the results obtained from the dynamic earthquake analysis by Perform 3D with the experimental ones. The main contribution of the developed model is taking into account parameters like the effect of eccentricity, column axial load, slab, wide beams and transverse beams on the seismic behavior of the connection region, besides the key parameters such as concrete compressive strength, reinforcement yield strength, joint width and joint transverse reinforcement ratio.

Seismic response of a structure is influenced by the inertial interaction between structure and deformable medium, on which the structure rests, due to flexibility and energy dissipation capability of the surrounding soil. The inertial interaction analyses can be performed by utilizing simplified soil-structure interaction (SSI) analyses methods. In literature, it is noted that varying soil conditions and foundation types can be modeled by using these SSI approaches with springdashpot couples having certain stiffness and damping. In this study, the seismic response of superstructure obtained by using simplified SSI methods is compared with those of the fixed base systems. For this purpose, single and multi degree of freedom structural systems are modeled with both spring&ndash / dashpot couple and fixed base models. Each system is analyzed for varying structural and soil stiffness conditions under the excitation of three different seismic records. Next, the total base shear acting on the structural system and internal forces of load bearing members are investigated to observe the inertial interaction and foundation uplift effects on the superstructure. It is also aimed to examine the compatibility of the simplified SSI approaches utilized in the analyses. It is concluded that the structural and soil stiffness parameters are the most influential parameters that affect seismic structural response. Structures becomemore sensitive to varying soil properties as the structural stiffness increases. On the other hand, decreasing soil stiffness also increases the sensitivity of the structure to the seismic excitation. Calculated values of total base shear and internal member forces revealed that the inertial interaction might be detrimental for the superstructure. Contrary to general belief, the fixed base approach does not always yield to the results, which are on the safe side. Considering the analysis results, it is concluded that SSI analysis is very useful for more precise and economical design for the seismic behavior.

The catastrophic damage to the infrastructure due to the most recent major earthquakes around the world demonstrated the seismic vulnerability of many existing reinforced concrete buildings. Accordingly, this thesis is focused on a proposed seismic retrofitting system (PSRS) configured to upgrade the performance of seismically vulnerable reinforced concrete buildings. The proposed system is composed of a rigid steel frame with chevron braces and a conventional energy dissipating shear link. The retrofitting system is installed within the bays of a reinforced concrete building frame. A retrofitting design procedure using the proposed seismic retrofitting system is also developed as part of this study. The developed design methodology is based on performance-based design procedure. The retrofitting design procedure is configured to provide a uniform dissipation of earthquake input energy along the height of the reinforced concrete building. The PSRS and a conventional retrofitting system using squat infill shear panels are applied to an existing school and an office building. Nonlinear time history analyses of the buildings in the original and retrofitted conditions are conducted to assess the efficiency of the PSRS. The analyses results revealed that the PSRS can efficiently alleviate the detrimental effects of earthquakes on the buildings. The building retrofitted with PSRS has a more stable lateral force-deformation behavior with enhanced energy dissipation capability than that of the one retrofitted with squat infill shear panels. For small intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is comparable to that of the one retrofitted with squat infill shear panels. But for moderate to high intensity ground motions, the maximum inter-story drift of the building retrofitted with the PSRS is considerably smaller than that of the one retrofitted with squat infill shear panels.

Most of the older reinforced concrete (RC) buildings have columns that are deficient when the current code requirements are considered. Therefore, performance of the columns determines the performance of the structure under the effects of earthquake induced lateral loads. It is recognized that no provision is proposed in TEC2007 to estimate the failure type called flexure-shear. Behavior of columns having probability of failing in flexure-shear failure mode is mostly underestimated by TEC2007 procedures. In addition, failure type classification of columns performed according to the linear and nonlinear procedures of TEC2007 needs to be examined with respect to the test results to cover all failure types including flexure-shear failure in order to lead the engineers develop economical and realistic retrofit solutions. In this study, different methods are explored to obtain reliable estimates for the performance of code deficient shear critical RC columns. Special considerations are given to Axial-Shear-Flexure interaction (ASFI) approach due to its mechanical background. After examination of different approaches, ASFI method with proposed modifications was selected as the most reliable model and lateral load-displacement analyses were performed on a database of shear critical columns. Findings were compared with the estimations of the nonlinear procedure given in Turkish Earthquake Code (TEC2007) for database columns. In addition, drift capacity equations and simplified safe drift capacity equations are proposed in light of statistical studies on the selected column specimens. In the last part of the study, performance evaluation of columns according to nonlinear procedures of FEMA 356, TEC2007, ASCE/SEI 41 update supplement, and EUROCODE 8 were conducted.

Damage and condition identi&amp / #64257 / cation of existing structures using non-destructive tests is a common challenge that has been worked on for a long time. In this study, two di&amp / #64256 / erent methods were developed to &amp / #64257 / nd existing force on cables as well as determine bending characteristics (EI coe&amp / #64259 / cients) of beam like structures (such as bridges). Comparing forces in symmetrically placed cables or against values obtained from design drawings would indicate structural imbalance as well as &amp / #64257 / nding EI coe&amp / #64259 / cients at a number of segments on a bridge girder might indicate weak regions that might possibly have undergone structural damage, having weak connections, lost composite action etc. With the help of the proposed algorithm, the sti&amp / #64256 / ness parameters of bridges can be assessed and the location of any damage that is in the magnitude which can a&amp / #64256 / ect displacement behavior of system can be located. The developed methods are demonstrated using the values analytically obtained from the created models and the e&amp / #64256 / ectiveness of the algorithm is criticized. Furthermore, several damage scenarios on a scaled lab beam was used to test the application using real experimental data / including tests on undamaged beam (for identi&amp / #64257 / cation) and tests on the damaged beam. Additional experiments were conducted on a cable stretched in the laboratory instrumented using a load cell to measure instantaneous axial load on the cable and compare these values against the values obtained from the developed tension measurement device. The results are compared and conclusions are derived.