The central focus of this dissertation is a seismic vulnerability assessment of retrofitted bridges. The objective of this work is to establish a methodology for the development of system level fragility curves for typical classes of retrofitted bridges using a probabilistic framework. These tools could provide valuable support for risk mitigation efforts in the region by quantifying the impact of retrofit on potential levels of damage over a range of earthquake intensities. The performance evaluation includes the development of high-fidelity three-dimensional nonlinear analytical models of bridges retrofit with a range of retrofit measures, and characterization of the response under seismic loading. Sensitivity analyses were performed to establish an understanding of the appropriate level of uncertainty treatment to model, assess, and propagate sources of uncertainty inherent to a seismic performance evaluation for portfolios of structures. Seismic fragility curves are developed to depict the impact of various retrofit devices on the seismic vulnerability of bridge systems. This work provides the first set of fragility curves for a range of bridge types and retrofit measures. Framework for their use in decision making for identification of viable retrofit measures, performance-based retrofit of bridges, and cost-benefit analyses are illustrated. The fragility curves developed as a part of this research will fill a major gap in existing seismic risk assessment software, and enable decision makers to quantify the benefits of various retrofits.

In this study, structural vulnerability of reinforced concrete frame structures by considering the country&ndash / specific characteristics is investigated to manage the earthquake risk and to develop strategies for disaster mitigation. Low&ndash / rise and mid&ndash / rise reinforced concrete structures, which constitute approximately 75% of the total building stock in Turkey, are focused in this fragility&ndash / based assessment. The seismic design of 3, 5, 7 and 9&ndash / story reinforced concrete frame structures are carried out according to the current earthquake codes and two dimensional analytical models are formed accordingly. The uncertainty in material variability is taken into account in the formation of structural simulations. Frame structures are categorized as poor, typical or superior according to the specific characteristics of construction practice and the observed seismic performance after major earthquakes in Turkey. The demand statistics in terms of maximum interstory drift ratio are obtained for different sets of ground motion records. The capacity is determined in terms of limit states and the corresponding fragility curves are obtained from the probability of exceeding each limit state for different levels of ground shaking. The results are promising in the sense that the inherent structural deficiencies are reflected in the final fragility functions. Consequently, this study provides a reliable fragility&ndash / based database for earthquake damage and loss estimation of reinforced concrete building stock in urban areas of Turkey.

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.

Buildings with torsional irregularity represent the main focus of many current investigations. However, despite this volume of research, there is no established framework that describes adequately the seismic vulnerability of reinforced concrete shear wall systems. In this study, the three-dimensional behavior of a particular shear-wall structure under earthquake effects was examined with regard to the nonlinear behavior of the reinforced concrete assembly and the parameters that characterize the structure exposed to seismic motion for damage assessment. A three story reinforced concrete shear-wall building was analyzed using the finite element method based ANSYS software. The scaled model building was subjected to shaking table tests at Saclay, France. The project was led by the Atomic Energy Agency (CEA Saclay, France) under the &ldquo / SMART 2008 Project.&rdquo / The investigation was conducted in two phases. In the first phase, the results of the finite element method and experiments were examined, and were reported in this study. For time history analysis, micro-modeling was preferred due to allowing inclusion the nonlinear effects of concrete and steel for analysis. The guiding parameters (acceleration, displacement, strain) of analytical results are compared with the corresponding values that were measured in the experiments to be able to quantify the validity of models and simulation. For the comparison of v the numerical model results with the experimental results FDE (Frequency Domain Error) method was used. After comparison of the numerical model results with the experimental results, the second phase of the SMART 2008 Project was undertaken. The second phase consisted of two parts summarized as &ldquo / Sensitivity Study&rdquo / and &ldquo / Vulnerability Analyses&rdquo / . However, in this report only the sensitivity study and fragility analyses will be reported. Sensitivity study was done to understand which parameters affect the response of the structure. Twelve parametric cases were investigated under two different ground motions. Different behavior parameters were investigated. The effective damping coefficient was found to affect the structural response at 0.2 g design level as well as at 0.6 g over-design level. At the design level, it was observed that elasticity modulus of concrete and additional masses on the specimen determined as effective on the calculated results. To derive the failure probabilities of this structure under various earthquake forces for the given limit states, fragility curves were obtained. Different seismic indicators such as PGA (Peak ground acceleration), PGV (Peak ground velocity), PGD (Peak ground displacement) and CAV (Cumulative absolute velocity) were used as seismic indicators and MISD (Maximum interstory drift) were used as damage indicator for fragility curves. In all 30 time history analyses were done. Regression analyses using least squares method were performed to determine the median capacity and its deviation. Correlation coefficients of the time history data versus fitted curves obtained from the regression analyses changes between 0.65 and 0.99. The lower cases were for PGD- MISD graphs. The scatter of the fragility curves calculated for each damage limit was slightly wider. HAZUS MH MR1 (2003) damage states were also used for the calculation of the fragility curves and compared with the SMART 2008 damage states.

The effectiveness of seismic retrofitting applied to enhance seismic performance was assessed for a five-story reinforced concrete (RC) flat-slab building structure in the central United States. In addition to this, an assessment of seismic fragility that relates the probability of exceeding a performance level to the earthquake intensity was conducted. The response of the structure was predicted using nonlinear static and dynamic analyses with synthetic ground motion records for the central U.S. region. In addition, two analytical approaches for nonlinear response analysis were compared. FEMA 356 (ASCE 2000) criteria were used to evaluate the seismic performance of the case study building. Two approaches of FEMA 356 were used for seismic evaluation: global-level and member-level using three performance levels (Immediate Occupancy, Life Safety and Collapse Prevention). In addition to these limit states, punching shear drift limits were also considered to establish an upper bound drift capacity limit for collapse prevention. Based on the seismic evaluation results, three possible retrofit techniques were applied to improve the seismic performance of the structure, including addition of shear walls, addition of RC column jackets, and confinement of the column plastic hinge zones using externally bonded steel plates. Finally, fragility relationships were developed for the existing and retrofitted structure using several performance levels. Fragility curves for the retrofitted structure were compared with those for the unretrofitted structure. For various performance levels to assess the fragility curves, FEMA global drift limits were compared with the drift limits based on the FEMA member-level criteria. In addition to this, performance levels which were based on additional quantitative limits were also considered and compared with FEMA drift limits.

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser. Även tryckt utgåva.

The aim of this paper is to analyze the pattern of speculation-led growth in Turkey. It is dependent on international capital flows, whose continuity becomes more and more critical given the current account deficit, which is estimated to reach 6.1% as a ratio to GDP at the end of 2005. The paper assesses the sustainability of this speculation-led growth in the context of EU enlargement and compares the current state of fragility with former crises in Turkey as well as in East Asia and Latin America. Following a severe financial crisis in 2001, Turkey has entered a new phase of fragile growth led by boom-euphoric expectations. The paper aims at explaining this new phase and the evolution of the risk perceptions of both the creditors as well as the debtors in this "speculation game" based on the post-Keynesian/Minskyan concepts of endogenous expectations and financial fragility. (author's abstract) / Series: Department of Economics Working Paper Series

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The aim of this paper is to analyze the fragility of the New Member States and accession countries in the Central Eastern and South Eastern European countries (henceforth Eastern Europe) to the turbulences in the global economy and the changes in the direction of the international capital flows. (author's abstract) / Series: Department of Economics Working Paper Series

I likhet med i andra länder har det i Sverige under vissa högkonjunkturer uppstått ett så betydande kapitalöverskott, att den finansiella marknaden fått problem att bemästra flödena. Konsekvensen har blivit att den aggregerade risknivån ökat i takt med stigande tillgångspriser. När väl en kontraktion uppstått, har det saknats kapital för att i ordnade former bemästra de nya ekonomiska förutsättningarna. Det är den utvecklingen som föregått kriserna 1878/79, 1921/22 och 1991/92. Temporära insatser har då måst ske vid sidan av det befintliga institutionella systemet. Forskningen ger för Sveriges del en kriskronologi för det finansiella området med krisåren 1763, 1817/18, 1857/58, 1878/79, 1907/08, 1921/22, 1932/33 och 1991/92. Det har vid kriserna 1878/79, 1921/22 och 1991/92 förelegat ett betydande hot om kollaps av det finansiella systemet. Vid dessa tre tillfällen har det efter förhandlingar mellan bankerna och staten kommit att skapas temporära krishanteringsorganisationer – Järnvägshypoteksfonden 1879, AB Kreditkassan 1922 samt Securum AB 1992 – vid sidan om den svenska Riksbanken. Kriserna har hävts med hjälp av de temporärt skapade krisorganisationerna, vilka samtliga har haft en Lender of Last Resort-funktion. Krishanteringstekniken vid krisen 1921/22 kan ses som en vidareutveckling av den som kommit till användning 1878/79. Även om bakgrunden till krisen 1991/92 skiljer sig åt från de två här tidigare nämnda tillfällena, kom tekniken med överflyttandet av tyngande engagemang till ett nytt bolag att likna den teknik som användes redan av AB Kreditkassan. Trots detta betydde tidigare svenska erfarenheter mindre för krisen 1991/92 i detta fall. Idéerna till Securum hämtades istället från senare tids bankkrishantering i USA med inrättandet av så kallade ”bad banks”. Syftet med denna avhandling är att med en institutionell ansats klarlägga och analysera hur de två första av dessa tre finansiella kriser har hanterats. Avhandlingen belyser i detalj det förhandlingsdrama mellan statens och marknadens aktörer som föregått inrättandet av respektive krisorganisation.