Steel Bridge Design Handbook - Design Example: Three …

1 Steel Bridge Design HandbookNovember Department of TransportationFederal Highway AdministrationDesign example 5: Three -Span Continuous Horizontally Curved Composite Steel Tub-Girder BridgePublication No. FHWA-IF-12-052 - Vol. 25 Archivedi Notice This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The Government assumes no liability for use of the information contained in this document. This report does not constitute a standard, specification, or regulation. Quality Assurance Statement The Federal Highway Administration provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information.

2 FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. Archivedii Steel Bridge Design Handbook Design example 5: Three -Span Continuous Horizontally Curved Composite Steel Tub-Girder Bridge Publication No. FHWA-IF-12-052 Vol. 25 November 2012 Archivediii Archivediv Technical Report Documentation Page 1. Report No. FHWA-IF-12-052 Vol. 25 2. Government Accession No. 3. Recipient s Catalog No. 4. Title and Subtitle Steel Bridge Design Handbook Design example 5: Three -Span Continuous Horizontally Curved Composite Steel Tub-Girder Bridge 5. Report Date November 2012 6. Performing Organization Code 7. Author(s) Brandon Chavel, , and Julie Rivera, 8. Performing Organization Report No. 9. Performing Organization Name and Address HDR Engineering, Inc.

3 11 Stanwix Street Suite 800 Pittsburgh, PA 15222 10. Work Unit No. 11. Contract or Grant No. 12. Sponsoring Agency Name and Address Office of Bridge Technology Federal Highway Administration 1200 New Jersey Avenue, SE Washington, 20590 13. Type of Report and Period Covered Technical Report March 2011 November 2012 14. Sponsoring Agency Code 15. Supplementary Notes 16. Abstract Tub girders , as closed-section structures, provide a more efficient cross section for resisting torsion than I- girders , which is especially important in horizontally curved highway bridges. The increased torsional resistance of a closed composite Steel tub girder also results in an improved lateral distribution of live loads. For curved bridges, warping, or flange lateral bending, stresses are lower in tub girders , when compared to I- girders , since tub girder carry torsion primarily by means of St.

4 Venant torsional shear flow around the perimeter of their closed sections, whereas I- girders have very low St. Venant torsional stiffness and carry torsion primarily by means of warping. This Design example illustrates the Design calculations for a curved Steel tub girder Bridge , considering the Strength, Service, fatigue and Constructibility Limits States in accordance with the AASHTO LRFD Bridge Designs specifications. Calculations are provided for Design checks at particular girder locations, a bolted field splice Design , an internal pier diaphragm Design , and a top flange lateral bracing member Design . 17. Key Words Steel Tub Girder Bridge , Steel box girder Bridge , LRFD, Bolted Field Splice, Top Flange Lateral Bracing, box girder Distortional Stresses 18. Distribution Statement No restrictions.

5 This document is available to the public through the National Technical Information Service, Springfield, VA 22161. 19. Security Classif. (of this report) Unclassified 20. Security Classif. (of this page) Unclassified 21. No of Pages 22. Price Form DOT F (8-72) Reproduction of completed pages authorized Archivedv Steel Bridge Design Handbook : Design example of a Three -Span Continuous Curved Composite Tub-Girder Bridge TABLE OF CONTENTS TABLE OF CONTENTS .. v LIST OF FIGURES .. x LIST OF TABLES .. xi FOREWORD .. xii INTRODUCTION .. 1 OVERVIEW OF LRFD ARTICLE .. 3 Design PARAMETERS .. 5 GENERAL Steel FRAMING CONSIDERATIONS .. 7 Span Arrangement .. 7 Field Section Sizes.

6 9 Bridge Cross Section and Girder Spacing .. 9 Internal and External Cross-Frame Bracing .. 10 Diaphragms at the Supports .. 12 Top Flange Lateral Bracing .. 12 FINAL Design .. 15 AASHTO LRFD Limit States .. 15 Strength Limit State .. 15 Service Limit State .. 15 Fatigue and Fracture Limit 15 Extreme Event Limit State .. 16 Constructibility .. 16 Loads .. 16 Dead Load .. 16 Deck Placement Sequence .. 17 Archivedvi Live Load .. 19 Centrifugal Force Computation .. 19 Load Combinations .. 23 ANALYSIS .. 25 Three -Dimensional Finite Element Analysis .. 25 Bearing Orientation and Arrangement .. 26 Live Load Analysis .. 27 Analysis Results .. 28 Design .. 36 Girder Section Proportioning .. 36 Girder Web Depth .. 38 Cross-section Proportions .. 39 Section Properties.

7 40 Section G2-1: Span 1 Positive Moment Section 41 Effective Width of Concrete Deck .. 42 Elastic Section Properties: Section G2-1 .. 43 Plastic Moment Neutral Axis: Section G2-1 .. 45 Section G2-2: Support 2 Negative Moment Section Properties .. 45 Elastic Section Properties: Section G2-2 .. 46 Check of Minimum Negative Flexure Concrete Deck Reinforcement (Article ) .. 49 Girder Check: Section G2-1, Constructibility (Article ) .. 50 Deck Overhang Bracket Load .. 51 Flange Lateral Bending Due to Web Shear .. 52 Flange Lateral Bending Due to Curvature .. 53 Top Flange Lateral Bending Amplification .. 54 Flexure (Article ) .. 55 Top 56 Bottom Flange .. 60 Girder Check: Section G2-1, Service Limit State (Article ) .. 61 Permanent Deformations (Article ) .. 61 Archivedvii Web 62 Girder Check: Section G2-1, Fatigue Limit State (Article ).

8 62 Special Fatigue Requirements for Webs .. 64 Girder Check: Section G2-1, Strength Limit State (Article ) .. 65 Flexure (Article ) .. 65 Top Flange Flexural Resistance in Compression .. 68 Bottom Flange Flexural Resistance in Tension .. 69 Concrete Deck Stresses .. 70 Girder Check: Section G2-2, Constructibility (Article ) .. 70 Flexure (Article ) .. 70 Top 72 Bottom Flange .. 73 Shear (Article ) .. 77 Girder Check: Section G2-2, Service Limit State (Article ) .. 79 Permanent Deformations (Article ) .. 79 Web 79 Girder Check: Section G2-2, Fatigue Limit State (Article ) .. 83 Cross-section Distortion Stresses .. 84 Girder Check: Section G2-2, Strength Limit State (Article ) .. 93 Flexure (Article ) .. 93 Top Flange .. 96 Bottom Flange .. 96 Cross-section Distortion Stresses.

9 103 Shear (Article ) .. 103 Interior Panel (Article ) .. 104 Bottom Flange Longitudinal Stiffener .. 106 Internal Pier Diaphragm Design .. 108 Web Shear Check .. 109 Noncomposite Shear Force .. 109 Composite Shear Force .. 111 Total Factored Shear Force .. 111 Archivedviii Check of Internal Diaphragm Web .. 112 Bearing Stiffeners .. 113 Bearing Resistance .. 115 Axial Resistance .. 115 Top Flange Lateral Bracing Design .. 117 Bolted Field Splice Design .. 124 Bolt Resistance for the Service Limit State and Constructibility .. 127 Bolt Resistance for the Strength Limit 128 Bolt Shear Resistance .. 128 Bearing Resistance on Connected Material .. 129 Constructibility Checks .. 130 Constructibility Check of Top Flange Splice Bolts .. 131 Constructibility Check of Bottom Flange Splice Bolts.

10 132 Constructibility Check of Web Splice Bolts .. 134 Service Limit State .. 137 Service Limit State Check of Top Flange Splice Bolts .. 139 Service Limit State Check of Bottom Flange Splice Bolts .. 140 Service Limit State Check of Web Splice Bolts .. 142 Strength Limit State .. 142 Positive Flexure Strength Limit State Design Forces .. 144 Negative Flexure Strength Limit State Design Forces .. 146 Summary of Flexure Strength Limit State Design Forces .. 148 Strength Limit State Check of Top Flange Splice Bolts .. 148 Strength Limit State Check of Bottom Flange Splice 148 Strength Limit State Check of Web Splice Bolts .. 150 Strength Limit State Check of Top Flange Splice Plates .. 155 Strength Limit State Check of Top Flange Splice Plates - Bearing .. 158 Strength Limit State Check of Bottom Flange Splice Plates.