Navigating Routine Steel Bridge Design
AASHTO LRFD Bridge DesignSpecifications 9th Edition
AISC2021
by
American Institute of Steel Construction
All rights reserved. This book or any part thereof must not be reproducedin any form without the written permission of the publisher. The AISC logo is a registered tradlemark of AISC.
The information presented in this publication has been prepared following recognized principles of designand construction.While it is believed to be accurate this information should not be used or relied uponfor any specific application without petent professional examination and verification of its accuracy suitability and applicability by a licensed engineer or architect. The publication of this information is not arepresentation or warranty on the part of the American Institute of Steel Construction its officers agents employees or mittee members or of any other person named herein that this information is suitablefor any general or particular use or of freedom from infringement of any patent or patents. All represen-tations or warranties express or mplied other than as stated above are specifically disclaimed. nyone making use of the information presented in this publication assumes all liability arising from such use.
Caution must be exercised when relying upon standlards and guicdlelines dleveloped by other bodies andincorporated by reference herein since such material may be modlified or amendled from time to time sub-for such material other than to refer to it and incorporate it by reference at the time of the initial publicationof this edition.
FOREWORD
The design of bridges requires the efforts of engineers educated and experienced in structuraldesign specifically the unique aspects of bridge design. However bridge design need not beplicated or challenging particularly for the more routine bridges which form a large part of the inventory of transportation structures in the United States. In particular the design of "“routinesteel I-girder bridges a workhorse structure type can be relatively simple if the engineer knowswhere to focus their efforts and is provided with guidance on how to streamline the morepredictable repetitive aspects of the design effort.
To this end the National Steel Bridge Alliance (NSBA) a division of the American Institute of Steel Construction (AISC) has developed this Guide to Navigating Routine Steel Bridge Design.The goal of this Guide is to help designers navigate the prehensive design provisions of theAASHTO LRFD Bridge Design Specifications (AASHTO LRFD BDS) identifying just theprovisions that are applicable to the design of routine steel I-girder bridges explaining how to apply those provisions remending practices proven to lead to economical designs andsuggesting ways to streamline the design effort.
This Guide is meant to be used as an interactive reference rather than as a textbook read fromcover to cover. The general flow of design tasks is outlined and at any point in the design processthe reader can quickly jump to a detailed Discussion of any particular AASHTO LRFD BDSbut can also increase their familiarity with and understanding of the AASHTO LRFD BDS.
We would like to gratefully acknowledge the support of Christopher Garrell (NSBA) who steeredthe development of this Guide. Credit is also due to Kaylene Callicoatt (HDR) who helpedprovided invaluable peer review ments during the writing of this Guide including: Travis Butz assemble and edit this Guide. Finally we would like to thank the numerous professionals who(Burgess and Niple) Matt Farrar (Idaho DOT) Jamie Farris (Texas DOT) Karl Frank(Consultant) Christina Freeman (Florida DOT) Dennis Golabek (WSP) John Holt (ModjeskiMedlock (High Steel Structures) Adam Price (Tennessee DOT) Curtis Rockiki (Texas DOT) Kevin Sear (AECOM) Tony Shkurti (HNTB) Jason Stith (Michael Baker International) GregWagdy Wassef (WSP) and Jaclyn Whelan (AECOM). Turco (Texas DOT) Jeffrey Vetter (Idaho DOT) Dayi Wang (Federal Highway Administration)
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NSBA Guide to Navigating Routine Steel Bridge Design / i
TABLEOFCONTENTS
SCOPE OF THIS GUIDE DETERMINATION DEFINITIONS. 3TERMINOLOGY 4DEFINITION CHECKLIST FOR A“ROUTINE STEEL I-GIRDER BRIDGE". DEFINITION OFA“ROUTINE STEEL I-GIRDER BRIDGE" 5USEFULREFERENCES.. I1GENERALFLOW OFDESIGN TASKS 15DESIGN TASK QUICK LINKS... GRAPHICAL INDEX OF DESIGN TASKS. 16 20General Considerations.. 21Deck Design. Resistance Factors and Load Modifiers 23 22Load Combinations and Load Factors 24Live Load Force Effects - Introduction. 25Live Load Force Effects - Flexure Live Load Force Effects - Shear 26 27Other Load Effects and Factors Affecting Load Effect Calculations 28Girder Flexure Design Constructibility.. Girder Flexure Design General . 30 29Girder Flexure Design Service Limit State. .31Girder Flexure Design Fatigue and Fracture Limit State... Girder Flexure Design Strength Limit State 32 33Girder Shear Design..Shear Connector Design... Stiffener Design. 36 35Splice Desig.. 37Bolted Connection Design Cross-Frame/Diaphragm Design.... 39 38Welded Connection Design.. .40Connection Design Miscellaneous Checks ...SECTION 1: INTRODUCTION. SECTION 2: GENERAL DESIGN AND LOCATION FEATURES .48 .42SECTION 3: LOADS AND LOAD FACTORS. 53SECTION 4: STRUCTURAL ANALYSIS AND EVALUATION SECTION 6:STEELSTRUCTURES 118 82CONCLUSION..... .412
