Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 333
Book Description
New load design factors and models are introduced to account for site-specific live-load demands in the state of New Jersey. Live-load for highway bridges is highly site specific. The current AASHTO LRFD design specifications provide a notional design truck to which load factors are applied. These strength design factors were calibrated using reliability theory to provide a consistent level of safety for various spans and bridge types. The original calibration was done using a small sample of data from decades ago. Truck weights and volumes have significantly increased, reducing the level of safety of highway bridges designed today. Live-load is quantified using an extensive weigh-in-motion (WIM) database for the state of New Jersey as well as instrumentation at a bridge located in the heart of Port Newark, NJ. An integrated system combines a WIM system to measure truck loads and a data logger to capture the strains and deflections. This, first of its kind, system provides a complete picture of bridge behavior. The WIM data collected include all of the parameters needed to quantify truck loading: gross and axle weights, axle spacings, classification, counts, speeds, lane, etc. The bridge response includes parameters such as: strains and deflections. Information on truck loads are used to develop load effect envelopes for various span lengths. The load effects are then extrapolated using Normal probability paper to predict the maximum expected levels for the full service life of 75 years. The effect of other distributions, various measurement durations, and truck multiple presence is also studied. Based on the analysis of moment and shear envelops for various spans, it was found that the current load factors must be increased to maintain the level of safety that the code dictates. A new load model is proposed to provide a more uniform bias for New Jersey trucks. Fatigue load effects are studied in terms of effective truck weights, truck dimensions, and multiple presence in comparison with current evaluation procedures. Experimental load and response data from the instrumented bridge along with computer models is used to study the effect of truck weight, volume, and multiple presence of the fatigue life. Statistical techniques developed by the automotive industry are applied to short experimental measurements to predict a fatigue load profile that would be expected if measurement extended to a much longer duration. The rainflow extrapolation techniques utilize Extreme Value Theory and non-parametric smoothing methods to render a future prediction of the rainflow counted stress cycle matrix. The effect of measurement duration, seasonality, and truck multiple presence on fatigue life prediction is studied.
Author: Joshua Benjamin White Publisher: ISBN: Category : Languages : en Pages : 560
Book Description
There have been a number of advances in the level of understanding of cross-frame systems for steel I-girder bridges; however, very little work has focused on the proper loading conditions to produce an adequate estimate of the fatigue load in cross-frames. The goal of this research is to provide an improved definition of the fatigue loading for cross-frames in straight, horizontally-curved, and skewed steel I-girder bridges which will be analyzed using refined analysis techniques. In order to compare load effects, three bridges were instrumented and monitored. The bridges include: i) a straight bridge with normal supports, ii) a straight bridge with skewed supports, and iii) a horizontally curved bridge with radial supports. Data gathered from the field instrumentation was used to validate three-dimensional finite element analysis (FEA) models that were used to carry out extensive parametric analyses to improve the understanding of the behavior of cross-frame stresses as a function of truck position on the bridge. A wide range of geometrical parameters of straight and horizontally curved bridges were used to understand the general behavior of the bridges. The primary objectives of this research include the following: 1) Investigate the adequacy of the current AASHTO (American Association of State Highway and Transportation Officials) fatigue load model for the design of cross frames in steel I-girder bridges. 2) Investigate the effects of multiple presence on the design of cross-frames in steel I-girder bridges. 3) Investigate the reliability of the developed load model and identify the gaps in knowledge of cross-frame detail resistance data as it relates to the reliability of current design practices. These objectives were accomplished by examining recently collected, high-resolution, multi-lane weigh-in-motion (WIM) data, which represent actual truck traffic records in the US. The current AASHTO fatigue design load model was evaluated by comparing cross-frame load effects caused by the fatigue load model to load effects caused by simulated truck traffic representing actual live load. Influence surfaces generated from three-dimensional FEA models provided information on the stresses in select cross-frame members as a function on truck position on the bridge deck. WIM data representing real truck traffic (tens of millions of truck records) were filtered and analyzed; multi-lane data were analyzed using a cluster analysis. The statistical parameters of this WIM study were used to simulate actual live load on the three-dimensional bridge models and compare load effects to those generated by a fatigue design truck. The outcome of this study indicates the current fatigue design truck axle and weight configuration and placement of the fatigue design truck to maximize design-controlling fatigue effects for both the Fatigue I and Fatigue II AASHTO limit states is overly conservative. Stochastic techniques were used to investigate the implications of new load factors in the context of reliability-based fatigue design
Author: Mark Douglas Bowman Publisher: Transportation Research Board ISBN: 030925826X Category : Technology & Engineering Languages : en Pages : 125
Book Description
"TRB's National Cooperative Highway Research Program (NCHRP) Report 721: Fatigue Evaluation of Steel Bridges provides proposed revisions to Section 7--Fatigue Evaluation of Steel Bridges of the American Association of State Highway and Transportation Officials Manual for Bridge Evaluation with detailed examples of the application of the proposed revisions."--Publisher's description.
Author: Airong Chen Publisher: Routledge ISBN: 1351208780 Category : Technology & Engineering Languages : en Pages : 124
Book Description
Bridges play important role in modern infrastructural system. This book provides an up-to-date overview of the field of bridge engineering, as well as the recent significant contributions to the process of making rational decisions in bridge design, assessment and monitoring and resources optimization deployment for the purpose of enhancing the welfare of society. Tang specifies the purposes and requirements of the conceptual bridge design, considering bridge types, basic elements, structural systems and load conditions. Cremona and Poulin propose an assessment procedure for existing bridges. Kallias et al. develop a framework for the performance assessment of metallic bridges under atmospheric exposure by integrating coating deterioration and corrosion modelling. Soriano et al. employ a simplified approach to estimate the maximum traffic load effect on a highway bridge and compare the results with other approaches based on on-site weigh-in-motion data. Akiyama et al. propose a method for reliability-based durability design and service life assessment of reinforced concrete deck slab of jetty structures. Chen et al. propose a meso-scale model to simulate the uniform and pitting corrosion of rebar in concrete and to obtain the crack patterns of the concrete with different rebar arrangements. Ruan et al. present a traffic load model for long span multi-pylon cable- stayed bridges. Khuc and Catbas implement a non-target vision- based method for the measurement of both static and dynamic displacements time histories. Finally, Cruz presents the career of the outstanding bridge engineer Edgar Cardoso in the fields of bridge design and experimental analysis. The book serves as a valuable reference to all concerned with bridge structure and infrastructure systems, including students, researchers, engineers, consultants and contractors from all areas sections of bridge engineering. The chapters originally published as a special issue in Structure and Infrastructure Engineering.
Author: Peter Dawe Publisher: Thomas Telford ISBN: 9780727732415 Category : Technology & Engineering Languages : en Pages : 192
Book Description
This book provides a detailed examination of all aspects of traffic loading and describes how design and assessment methods have evolved to deal with them.
Author: Chung Fu Publisher: ISBN: Category : Electronic books Languages : en Pages : 0
Book Description
Fatigue is a common failure mode of steel bridges induced by truck traffic. Despite the deterioration caused by environmental factors, the increasing truck traffic volume and weight pose a premier threat to steel highway bridges. Given the uncertainties of the complicated traffic loading and the complexity of the bridge structure, fatigue evaluation based on field measurements under actual traffic flow is recommended. As the quality and the quantity of the available long-term traffic monitoring data and information have been improved, methodologies have been developed to obtain more realistic vehicular live load traffic. A case study of a steel interstate highway bridge using microscopic traffic simulation is presented herein. The knowledge of actual traffic loading may reduce the uncertainty involved in the evaluation of the load-carrying capacity, estimation of the rate of deterioration, and prediction of remaining fatigue life. This chapter demonstrates a systematic approach using traffic simulation and bridge health monitoring-based fatigue assessment.
Author: Scott Walbridge Publisher: Springer Nature ISBN: 9811905118 Category : Technology & Engineering Languages : en Pages : 657
Book Description
This book comprises the proceedings of the Annual Conference of the Canadian Society of Civil Engineering 2021. The contents of this volume focus on specialty conferences in construction, environmental, hydrotechnical, materials, structures, transportation engineering, etc. This volume will prove a valuable resource for those in academia and industry.
Author: 
Author: Joshua Benjamin White
Author: Mark Douglas Bowman
Author: National Research Council (U.S.). Highway Research Board
Author: Airong Chen
Author: Fred Moses
Author: Piya Chotickai
Author: Peter Dawe
Author: Chung Fu
Author: Scott Walbridge