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Development Of Bridge Fragility Curves Using Near Fault And Far Field Earthquake Ground Motion Data
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Book Synopsis Development of Bridge Fragility Curves Using Near Fault and Far Field Earthquake Ground Motion Data by : Kuan-hsoung Chen
Download or read book Development of Bridge Fragility Curves Using Near Fault and Far Field Earthquake Ground Motion Data written by Kuan-hsoung Chen and published by . This book was released on 2002 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Near-fault Ground Motion Characteristics on Bridges with Footing Uplift by : Yuanzhi Chen
Download or read book Effect of Near-fault Ground Motion Characteristics on Bridges with Footing Uplift written by Yuanzhi Chen and published by . This book was released on 2017 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Urban areas have experienced tremendously growth in seismically active zone since last century. Only in recent decades it has been realised that the shaking closely adjacent to a fault (e.g. within 20 km) produced a different effect on the seismic loading from far-source induced shaking. The immense cost of damage due to the near-fault earthquakes emphasized the importance of studying near-fault ground motions and their effects on structures. In conventional seismic design, footing uplift is not permitted, thus the energy can only dissipate though the damping of the structure and plastic hinge development at a specific location. Plastic hinge development, within limits, helps to improve the safety of people. However, recent research indicates that plastic hinging due to near-fault earthquakes is more significant than that caused by far-field excitations, which has a substantial impact on economics and functionality. Therefore, the research reported in this PhD thesis considers an innovative low-damage seismic design philosophy: mitigate the damage resulting from near-fault excitations by incorporating footing uplift. Previous research on footing uplift focused on the structural response. The footing response, including the contact forces at the interface of the footing and support, is investigated in this study for the first time. The outcomes of this research provide the basis of holistic low-damage seismic design. This research starts with a simple experimental system to provide a rational interpretation of the structure and footing response including the effect of uplift. The effects of the supporting soil, the characteristics of the earthquake excitations and the structural plastic hinge development were then incorporated to enhance the understanding of this topic. To achieve this objective, a series of shake table experiments were conducted on physical models with different scales. The series of testing consisted of three groups of experiments with consideration of varying support and loading conditions: (1) a bridge pier with footing uplift on a rigid base under free-vibration induced by an initial vertical footing displacement, harmonic and strong earthquake base excitations, (2) a bridge pier with soil-foundation structure interaction under near-fault and far-field excitations, (3) a single bridge span with footing uplift on a rigid base and with strong vertical excitations included for the first time. The correct similitude of an uplifting structure on a rigid base, within the scaling laws, were addressed and applied to the experiments. Sensors were attached at the interface of the footing and support, i.e. load cells, a pressure mapping sensor and strain gauges, to reveal the contact forces due to footing uplift. The results shown in this thesis provide an experimental verification for existing theoretical models of structures with uplift. This research showed that near-fault horizontal excitation with strong pulses dominated the footing response. However, under horizontal ground motion without a pulse, the vertical component had the main effect on uplift. Uplift sometimes caused a lower contact force compared with the fixed base case. Moreover, a system designed with multiple energy dissipating mechanisms, i.e. foundation soil yielding, footing uplift and structural plastic hinge development, were likely to avoid the excessive rotation sometimes observed in structures with a single nonlinear mechanism.
Book Synopsis Seismic Design Methodologies for the Next Generation of Codes by : P. Fajfar
Download or read book Seismic Design Methodologies for the Next Generation of Codes written by P. Fajfar and published by Routledge. This book was released on 2019-09-10 with total page 619 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings, arising from an international workshop, present research results and ideas on issues of importance to seismic risk reduction and the development of future seismic codes.
Book Synopsis Effect of Directionality of Multi-component Ground Motions on Bridge Fragility Curves by : Marco Torbol
Download or read book Effect of Directionality of Multi-component Ground Motions on Bridge Fragility Curves written by Marco Torbol and published by . This book was released on 2011 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on developing, evaluating and testing a new approach to seismic risk assessment of highway transportation networks. Throughout the years many researches have been conducted on each different step used in this dissertation. Most of these steps use a probabilistic approach for each single problem; Monte Carlo simulation is the brute force approach used by this dissertation, however some assumptions throughout the process were necessary to achieve results that could be useful to the final user, decision maker. When dealing with the damageability of an infrastructure network, it is necessary to start from the study of the damageability of each vulnerable component. For highway transportation networks subject to a seismic event bridges are the vulnerable component. With enough time, enough information and enough manpower the best approach is step by step: to build an analytical model for each bridge, to perform probabilistic seismic hazard analysis PSHA at each bridge site and to assess the seismic vulnerability of each bridge. Unfortunately, when dealing with large networks, bridges are present in hundreds or even thousands (LA-OC network has more than 3000 bridges; therefore subdivision in classes and prototyping of each class is necessary to reduce the problem to a more manageable dimension. a single prototype that represents its entire class is analyzed and its damageability is applied to the entire class. Fragility curves will be used to represents the bridges' damageability. Different contributions are developed in this dissertation; the fundamental one is the development of fragility curves with two uni-variate random variables. The first will be the Intensity Measure of the ground motion; the second will be the angle of seismic incidence from which the ground motion struck the structure. Bridges with the same damageability class, located at different places within the network will behave differently under the same earthquake scenario, even if the intensity measure is the same, because of their different axis orientation and angle of seismic incidence. Therefore the spatial distribution properties of the network are taken into account when performing SRA. The development of a new software was necessary for the application of these new fragility curves to the SRA of highway transportation networks.
Book Synopsis Spatial Variation of Earthquake Ground Motion and Development of Bridge Fragility Curves by : Vinita Saxena
Download or read book Spatial Variation of Earthquake Ground Motion and Development of Bridge Fragility Curves written by Vinita Saxena and published by . This book was released on 2000 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Design and Retrofit of Bridges by : M. J. N. Priestley
Download or read book Seismic Design and Retrofit of Bridges written by M. J. N. Priestley and published by John Wiley & Sons. This book was released on 1996-04-12 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of their structural simplicity, bridges tend to beparticularly vulnerable to damage and even collapse when subjectedto earthquakes or other forms of seismic activity. Recentearthquakes, such as the ones in Kobe, Japan, and Oakland,California, have led to a heightened awareness of seismic risk andhave revolutionized bridge design and retrofit philosophies. In Seismic Design and Retrofit of Bridges, three of the world's topauthorities on the subject have collaborated to produce the mostexhaustive reference on seismic bridge design currently available.Following a detailed examination of the seismic effects of actualearthquakes on local area bridges, the authors demonstrate designstrategies that will make these and similar structures optimallyresistant to the damaging effects of future seismicdisturbances. Relying heavily on worldwide research associated with recentquakes, Seismic Design and Retrofit of Bridges begins with anin-depth treatment of seismic design philosophy as it applies tobridges. The authors then describe the various geotechnicalconsiderations specific to bridge design, such as soil-structureinteraction and traveling wave effects. Subsequent chapters coverconceptual and actual design of various bridge superstructures, andmodeling and analysis of these structures. As the basis for their design strategies, the authors' focus is onthe widely accepted capacity design approach, in which particularlyvulnerable locations of potentially inelastic flexural deformationare identified and strengthened to accommodate a greater degree ofstress. The text illustrates how accurate application of thecapacity design philosophy to the design of new bridges results instructures that can be expected to survive most earthquakes withonly minor, repairable damage. Because the majority of today's bridges were built before thecapacity design approach was understood, the authors also devoteseveral chapters to the seismic assessment of existing bridges,with the aim of designing and implementing retrofit measures toprotect them against the damaging effects of future earthquakes.These retrofitting techniques, though not considered appropriate inthe design of new bridges, are given considerable emphasis, sincethey currently offer the best solution for the preservation ofthese vital and often historically valued thoroughfares. Practical and applications-oriented, Seismic Design and Retrofit ofBridges is enhanced with over 300 photos and line drawings toillustrate key concepts and detailed design procedures. As the onlytext currently available on the vital topic of seismic bridgedesign, it provides an indispensable reference for civil,structural, and geotechnical engineers, as well as students inrelated engineering courses. A state-of-the-art text on earthquake-proof design and retrofit ofbridges Seismic Design and Retrofit of Bridges fills the urgent need for acomprehensive and up-to-date text on seismic-ally resistant bridgedesign. The authors, all recognized leaders in the field,systematically cover all aspects of bridge design related toseismic resistance for both new and existing bridges. * A complete overview of current design philosophy for bridges,with related seismic and geotechnical considerations * Coverage of conceptual design constraints and their relationshipto current design alternatives * Modeling and analysis of bridge structures * An exhaustive look at common building materials and theirresponse to seismic activity * A hands-on approach to the capacity design process * Use of isolation and dissipation devices in bridge design * Important coverage of seismic assessment and retrofit design ofexisting bridges
Book Synopsis Fragility Considerations in Highway Bridge Design by : Masanobu Shinozuka
Download or read book Fragility Considerations in Highway Bridge Design written by Masanobu Shinozuka and published by . This book was released on 2007 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Fragility Assessment of Highway Bridges by : Seyyed Nima Mahmoudi
Download or read book Seismic Fragility Assessment of Highway Bridges written by Seyyed Nima Mahmoudi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Fragility curves are useful tools for reliability evaluation of structures as well as for identifying the most vulnerable components. This study focuses on the seismic fragility analysis of highway bridges. Two main approaches are used for this purpose: component-based and system-based fragility analyses. The seismic vulnerability of two existing bridges located in Montreal are assessed as case studies.The main goal of this study is to develop reliable seismic fragility curves for highway bridge structures considering all significant uncertainties involved. Uncertainties include those associated with modelling structural behavior, seismic inputs and definition of component capacities. The procedures are implemented for the fragility assessment of two existing bridges as case studies. For this purpose, deterioration due to corrosion of reinforcing steel and its effects on structural behavior are included, as well as validation of the Finite Element Model using dynamic properties obtained from ambient noise measurements. Proposed methods for the selection of appropriate set of ground motion records, the type of model analysis and probabilistic modeling of component capacities are presented and illustrated for the two case studies.Two stochastic methods are proposed for validating the Finite Element Model of a bridge. The first method is based on classical hypothesis testing procedures while the second uses a Bayesian updating approach. The stochastic methods are also used to update the input parameters, detect probable major damage in the bridges and determine the confidence interval on model responses as a function of laboratory test data and field observations.In order to limit the uncertainties involved in seismic inputs, a state-of-the-art ground motion record selection procedure based on Conditional Mean Spectrum (CMS) is used. Incremental Dynamic Analysis (IDA) is performed to evaluate the record to record variability in seismic responses and to capture the nonlinearity in structural component behaviors.The first part of the thesis describes the application of component-based fragility analysis for the seismic vulnerability assessment of highway bridge structures. IDA is performed on the validated Finite Element model of the structure using an appropriate set of ground motion records. The results are used for estimating the relationships between ground motion intensity measures and component demands. A Joint Probabilistic Seismic Demand Model (JPSDM) is fitted to the results in order to develop component and system fragility curves of the structure.Since the component based fragility analysis of complex structures comprising a large number of components requires enormous computational efforts, in the second part of this study, a system-based approach for developing seismic system fragility curves is proposed which uses Support Vector Machines (SVM). SVM is a state-of-the-art machine learning technique which is used to discover patterns in highly dimensional and complex data sets. In this application, SVM is used to determine the relationship between ground motion intensity measures and peak structural responses. Seismic fragility curves are developed using Probabilistic SVM (PSVM). Finally, the efficiency of the proposed PSVM method for its application to vector-valued ground motion Intensity Measures (IM) as well as traditional single-valued IM are investigated." --
Book Synopsis Seismic Response Prediction of Instrumented Pre-1971 Highway Bridges in California by : Dong Wang
Download or read book Seismic Response Prediction of Instrumented Pre-1971 Highway Bridges in California written by Dong Wang and published by . This book was released on 2020 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent earthquake disasters have demonstrated the seismic vulnerability of highway bridge systems and the significance of the ensuing social impact. Rapid seismic assessment of regional highway bridges is critical to help reduce the severe loss of life and property. Firstly, the typical modeling technique for reinforcement concrete highway bridges is introduced using specific elements for different components. However, the modeling procedures are material-level parameter-dependent and time-consuming. The nonlinear analysis convergence is also a frustrating problem for numerical simulation. Due to these realistic limitations, a simple, fast, and robust numerical model that can be developed with only component-level information needs to be adopted. It's shown that the bridge bent representation can be simplified as a single degree of freedom system. The force-displacement relationship of the bridge can be roughly approximated by a bilinear curve. So a simplified 2D bilinear model is adopted for highway bridges throughout the study. Secondly, the statistical distributions for selected bridge input parameters can be derived based on the regional bridge inventory. Then an iterative process by sampling and filtering input parameters can be used to generate as many bridge candidates as possible for a specific region. The proposed bridge models and selected historical ground motions will be utilized to develop a seismic response prediction model using machine learning for an instrumented highway bridge. This study investigates the optimal features to represent the highway bridge and ground motion. Different regression models are applied for bridges with near-fault motion, and it's shown the accuracy of the guided machine learning prediction model has exceeded the performance of traditional methods. A discounted accuracy is observed when applying the same machine learning prediction model in the highway bridge with far-field ground motion, And a two-layer LSTM network is developed with a new representation of far-field ground motion as the input.
Book Synopsis Uncertainty Treatment in Performance Based Seismic Assessment of Typical Bridge Classes in United States by : Mohammad Mehdizadeh
Download or read book Uncertainty Treatment in Performance Based Seismic Assessment of Typical Bridge Classes in United States written by Mohammad Mehdizadeh and published by . This book was released on 2014 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridge networks are expensive and complex infrastructures and are essential components of today's transportation systems. Despite the advancement in computer aided modeling and increasing the computational power which is increasing the accessibility for developing the fragility curves of bridges, the complexity of the problem and uncertainties involved in fragility analysis of the bridge structures in addition to difficulties in validating the results obtained from the analysis requires precaution in utilization of the results as a decision making tool. The main focus of this research is to address, study and treatment of uncertainties incorporated in various steps of performance based assessments (PBA) of the bridge structures. In this research the uncertainties is divided into three main categories. First, the uncertainties that come from ground motions time and frequency content alteration because of scarcity of the recorded ground motions in the database. Second, uncertainties associated in the modeling and simulation procedure of PBA, and third uncertainties originated from simplistic approach and methods utilized in the conventional procedure of PBA of the structures. Legitimacy of the scaling of ground motions is studied using the response of several simple nonlinear systems to amplitude scaled ground motions suites. Bias in the response obtained compared to unscaled records for both as recorded and synthetic ground motions. Results from this section of the research show the amount of the bias is considerable and can significantly affect the outcome of PBA. The origin of the bias is investigated and consequently a new metric is proposed to predict the bias induced by ground motion scaling without nonlinear analysis.
Book Synopsis Dynamic Response of Bridges to Near-fault, Forward Directivity Ground Motions by : Eliot Bonvalot
Download or read book Dynamic Response of Bridges to Near-fault, Forward Directivity Ground Motions written by Eliot Bonvalot and published by . This book was released on 2006 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Seismic Response and Analytical Fragility Functions for Curved Concrete Box-girder Bridges by : Reihaneh Sarraf Shirazi
Download or read book Seismic Response and Analytical Fragility Functions for Curved Concrete Box-girder Bridges written by Reihaneh Sarraf Shirazi and published by . This book was released on 2015 with total page 642 pages. Available in PDF, EPUB and Kindle. Book excerpt: Curved bridges are constructed to conform to geometric constraints resulting from traffic and structural restrictions. They are different from their straight counterparts since the response coupling in the longitudinal and transverse directions and rotation of the superstructure may lead to significantly different seismic response. Observations from past earthquakes highlighted the seismic vulnerability of these bridges due to this coupled response. The consequence of bridge damage on the performance of transportation system is commonly assessed through Seismic Risk Assessment (SRA) of lifeline systems. Thus, seismic fragility curves are essential input to SRA to estimate damage to highway bridges and consequently to the network. The literature review shows shortcomings in fragility studies on the effect of horizontal curvature of bridges, specifically concrete box-girder bridges. This study aims to fill in the gap on the current state-of-the-knowledge in the seismic response and vulnerability of curved concrete box-girder bridges. Since this bridge type is common in California, the modern details adopted by CALTRANS along with the current seismic design considerations from SDC (2013) are used to select the representative benchmark bridges. To incorporate the uncertainty in geometrical, structural, and material properties of bridges into the analytical models, five sets of statistical bridge samples (each includes 160 bridges) with various subtended angles are developed. These bridge models are subjected to four sets of ground motions representing different site soil conditions and spectral characteristics. A total of 800 response history analyses are performed and the results are used to develop analytical component and system fragility functions for a range of subtended angles. A comprehensive study on the effect of horizontal curvature on the bridge dynamic characteristics and component seismic response is conducted. The median of system (bridge) fragility curves are proposed as a function of the subtended angle for each ground motion set. These functions can be used as input into SRA tools. The fragility analysis shows that the seismic vulnerability of bridges depends on the soil condition of the site and ground motion characteristics as well as the horizontal curvature of the bridge. Columns are found to have the most significant contribution to the system fragility curves. The analyses confirm that the current seismic details including PTFE/spherical bearings and isolated shear keys, suggested by CALTRANS, achieve the objectives of capacity-protected design of piles. Since the dynamic characteristics of bridges are sensitive to the curvature, curved bridges with subtended angles greater than 30 degrees require explicit modeling of curved geometry. In curved bridges, the coupling of transverse and longitudinal modes reduces the dominance of the fundamental mode in the bridge response and leads to the contribution of higher modes. The statistical evaluation of structural demands indicates that the curvature and the torsion demands on columns are amplified in curved bridges.
Book Synopsis Dynamic Response of the Suspension Spans of the San Francisco-Oakland Bay Bridge by : L. Hutchings
Download or read book Dynamic Response of the Suspension Spans of the San Francisco-Oakland Bay Bridge written by L. Hutchings and published by . This book was released on 2005 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic response of the suspension spans of the San Francisco-Oakland Bay Bridge (SFOBB) have been numerically modeled in a case-study to investigate the effects of long-period, near-field ground motions on flexible suspension bridges. The structural simulation model used in the study was developed as a special purpose computer program tailored to efficiently simulate the nonlinear response of cable supported bridges. The simulation model includes a number of special element technologies and solution algorithms that enable efficient nonlinear analysis of suspension bridges. The ground motions used in the study were site specific synthetic records for a Mw=7.25 earthquake along the Hayward fault at 12-15 km distant, and actual measured near-field records from the Izmit Turkey (1999) and Chi-Chi Taiwan (1999) earthquakes. These records include near- and far-field broad-band motions for three components. The results of the numerical simulations indicate that low frequency waveforms associated with near-field motions can place a significant demand on the structural systems of suspension bridges, and must be accounted for in suspension bridge analysis and design.
Book Synopsis Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges by : Nigel Powers
Download or read book Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges written by Nigel Powers and published by CRC Press. This book was released on 2018-07-04 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges contains lectures and papers presented at the Ninth International Conference on Bridge Maintenance, Safety and Management (IABMAS 2018), held in Melbourne, Australia, 9-13 July 2018. This volume consists of a book of extended abstracts and a USB card containing the full papers of 393 contributions presented at IABMAS 2018, including the T.Y. Lin Lecture, 10 Keynote Lectures, and 382 technical papers from 40 countries. The contributions presented at IABMAS 2018 deal with the state of the art as well as emerging concepts and innovative applications related to the main aspects of bridge maintenance, safety, risk, management and life-cycle performance. Major topics include: new design methods, bridge codes, heavy vehicle and load models, bridge management systems, prediction of future traffic models, service life prediction, residual service life, sustainability and life-cycle assessments, maintenance strategies, bridge diagnostics, health monitoring, non-destructive testing, field testing, safety and serviceability, assessment and evaluation, damage identification, deterioration modelling, repair and retrofitting strategies, bridge reliability, fatigue and corrosion, extreme loads, advanced experimental simulations, and advanced computer simulations, among others. This volume provides both an up-to-date overview of the field of bridge engineering and significant contributions to the process of more rational decision-making on bridge maintenance, safety, risk, management and life-cycle performance of bridges for the purpose of enhancing the welfare of society. The Editors hope that these Proceedings will serve as a valuable reference to all concerned with bridge structure and infrastructure systems, including students, researchers and engineers from all areas of bridge engineering.
Book Synopsis Post-earthquake Traffic Capacity of Modern Bridges in California by : Vesna Terzic
Download or read book Post-earthquake Traffic Capacity of Modern Bridges in California written by Vesna Terzic and published by . This book was released on 2010 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: The test results were then used to calibrate a finite element model of a bridge column. This bridge column model was incorporated into a hybrid model of a typical California overpass bridge and tested using the hybrid simulation technique. The finite element model of the typical California overpass bridge was validated using the data from hybrid simulations. The validated model of the typical bridge was used to evaluate its post-earthquake truck load capacity in an extensive parametric study that examined the effects of different ground motions and bridge modeling parameters such as the boundary conditions imposed by the bridge abutments, the location of the truck on the bridge, and the amount of bridge column residual drift. The principal outcomes of this study are the following findings.
Book Synopsis Dynamic Response of Bridges to Near Fault, Forward Directivity Ground Motions by : Adrian Rodriguez-Marek
Download or read book Dynamic Response of Bridges to Near Fault, Forward Directivity Ground Motions written by Adrian Rodriguez-Marek and published by . This book was released on 2008 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analytical Fragility Curves for Highway Bridges in Moderate Seismic Zones by : Bryant G. Nielson
Download or read book Analytical Fragility Curves for Highway Bridges in Moderate Seismic Zones written by Bryant G. Nielson and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Historical seismic events such as the San Fernando earthquake of 1971 and the Loma Prieta earthquake of 1989 did much to highlight the vulnerabilities in many existing highway bridges. However, it was not until 1990 that this awareness extended to the moderate seismic regions such as the Central and Southeastern United States (CSUS). This relatively long neglect of seismic issues pertaining to bridges in these moderate seismic zones has resulted in a portfolio of existing bridges with seismic deficiencies which must be assessed and addressed. An emerging decision tool, whose use is becoming ever increasingly popular in the assessment of this seismic risk, is that of seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake of a given intensity level. As much research has been devoted to the implementation of fragility curves in risk assessment packages, a great need has arisen for bridge fragility curves which are reliable, particularly for those in moderate seismic zones. The purpose of this study is to use analytical methods to generate fragility curves for nine bridge classes which are most common to the CSUS. This is accomplished by first considering the existing bridge inventory and assessing typical characteristics and details from which detailed 3-D analytical models are created. The bridges are subjected to a suite of synthetic ground motions which were developed explicitly for the region. Probabilistic seismic demand models (PSDM) are then generated using these analyses. From these PSD models, fragility curves are generated by considering specific levels of damage which may be of interest. The fragility curves show that the most vulnerable of all the bridge nine bridge classes considered are those utilizing steel girders. Concrete girder bridges appear to be the next most vulnerable followed by single span bridges of all types. Various sources of uncertainty are considered and tracked throughout this study, which allows for their direct implementation into existing seismic risk assessment packages.
