LOAD RATING HIGHWAY BRIDGES In accordance with Load and Resistance Factor Rating Method First Edition The first comprehensive text introducing the background theory along with the practical procedure of load rating highway bridges with the state-of-the-art Load and Resistance Factor Rating (LRFR) method. With its simplicity and complete contents on this subject, this is an indispensable text for both students and practicing engineers. The safety of bridges is essential to the traveling public. To ensure that bridges in our highway system function safely and serve properly, engineers need to inspect and assess the live load carrying capacity of the bridges. Based on the results of inspection and evaluation, decisions are made on load restriction, repair, retrofit or replacement. Load rating, one of the critical tasks in this decision-making process, uses either an analytical method or non-destructive load testing to determine the live load carrying capacity of a bridge. This is a book solely concentrated on bridge load rating by using analytical load rating methods, with a focus on the LRFR method. The primary purpose of this book is to provide the basic concept of load rating highway bridges in terms of the LRFR method. The target readers are practicing engineers who want to acquire fundamental knowledge of the LRFR method. Bearing that in mind, the author attempts to strike a balance between theory and how-to. Engineers who are conducting or will perform load ratings of bridges can use this text as a reference in supplement to the AASHTO Manual for Bridge Evaluation (MBE). This book can also serve as a textbook or supplemental material for a senior level undergraduate or graduate course in bridge design and load rating. This text is divided into three major sections. The first section contains a brief introduction to bridge load rating (Chapter 1) and fundamentals of structural failure and structural reliability theory (Chapter 2). After completing this section, re

A new, all inclusive manual that incorporates Allowable Stress, Load Factor, and Load and Resistance Factor Rating methods into one publication. This manual provides guidelines for the procedures and policies for determining the physical condition, maintenance needs, and load capacity of highway bridges. Rating examples are also included. It has been developed to assist bridge owners in establishing inspection procedures and evaluation practices that meet the National Bridge Inspection Standards (NBIS).

The purpose of this project is to validate the draft New York State Department of Transportation LRFR Engineering Instruction developed to provide guidance on application of the LRFR methodology as specified in the AASHTO Manual for Bridge Evaluation to the evaluation of bridges in New York State through the testing of Level II and Level I ratings to support LRFR implementation. This report documents the Level I ratings of 23 complex bridges and culverts using 2D and 3D finite element (FE) analysis methods. Ratings and load posting evaluations were determined based on both EI 05-034 and the Draft LRFR EI to compare the results of the Load Factor Rating (LFR) and LRFR methodologies. The impact of LRFR ratings on load postings and R-postings for NYS bridges is evaluated. The report provides guidance in load rating and posting requirements of AASHTO Specialized Hauling Vehicles (SHVs) for both LFR and LRFR methodologies, proposes updates to the LFR based EI 05-034 “Load Rating/Posting Guidelines for State Owned Highway Bridges,” documents suggested “Load and Resistance Factor Rating (LRFR) Blue Pages,” describes an approach to derive LRFR Condition Factors using AASHTO element inspection data, and documents recommended revisions to the draft LRFR EI. In addition, a statewide bridge inventory screening for SHV and the FAST Act Emergency Vehicles (EV) is performed and the results are presented.

Condition assessment and safety verification of existing bridges and decisions as to whether bridge posting is required are addressed through analysis, load testing, or a combination of methods. Bridge rating through structural analysis is by far the most common procedure for rating existing bridges. The American Association of State Highway and Transportation Officials (AASHTO) Manual for Bridge Evaluation (MBE), First Edition permits bridge capacity ratings to be determined through allowable stress rating (ASR), load factor rating (LFR) or load and resistance factor rating (LRFR); the latter method is keyed to the AASHTO LRFD Bridge Design Specifications, which is reliability-based and has been required for the design of new bridges built with federal findings since October, 2007. A survey of current bridge rating practices in the United States has revealed that these three methods may lead to different ratings and posting limits for the same bridge, a situation that carries serious implications with regard to the safety of the public and the economic well-being of communities that may be affected by bridge postings or closures. To address this issue, a research program has been conducted with the overall objective of providing recommendations for improving the process by which the condition of existing bridge structures is assessed. This research required a coordinated program of load testing and finite element analysis of selected bridges in the State of Georgia to gain perspectives on the behavior of older bridges under various load conditions. Structural system reliability assessments of these bridges were conducted and bridge fragilities were developed for purposes of comparison with component reliability benchmarks for new bridges. A reliability-based bridge rating framework was developed, along with a series of recommended improvements to the current bridge rating methods, which facilitate the incorporation of various in situ conditions of existing bridges into the bridge rating process at both component and system levels. This framework permits bridge ratings to be conducted at three levels of increasing complexity to achieve the performance objectives, expressed in the terms of reliability, that are embedded in the LRFR option of the AASHTO Manual of Bridge Evaluation. This research was sponsored by the Georgia Department of Transportation, and has led to a set of Recommended Guidelines for Condition Assessment and Evaluation of Existing Bridges in Georgia.