Composite Beam Design Manual - Computers and Structures

206 Pages·2015·4.31 MB·English

by  Randy Corson

Composite Beam Design Manual
AISC 360-10
Composite Beam
Design Manual
AISC 360-10
For ETABS® 2016

ISO ETA122815M54 Rev. 0
Proudly developed in the United States of America December 2015
Copyright
Copyright  Computers & Structures, Inc., 1978-2015
All rights reserved.

The CSI Logo®, SAP2000®, ETABS®, and SAFE® are registered trademarks of
Computers & Structures, Inc. Watch & LearnTM is a trademark of Computers &
Structures, Inc.

The computer programs SAP2000® and ETABS® and all associated documentation are
proprietary and copyrighted products. Worldwide rights of ownership rest with
Computers & Structures, Inc. Unlicensed use of these programs or reproduction of
documentation in any form, without prior written authorization from Computers &
Structures, Inc., is explicitly prohibited.
No part of this publication may be reproduced or distributed in any form or by any
means, or stored in a database or retrieval system, without the prior explicit written
permission of the publisher.
Further information and copies of this documentation may be obtained from:
Computers & Structures, Inc.
http://www.csiamerica.com/

[email protected] (for general information)
[email protected] (for technical support)
DISCLAIMER
CONSIDERABLE TIME, EFFORT AND EXPENSE HAVE GONE INTO THE
DEVELOPMENT AND DOCUMENTATION OF THIS SOFTWARE. HOWEVER,
THE USER ACCEPTS AND UNDERSTANDS THAT NO WARRANTY IS
EXPRESSED OR IMPLIED BY THE DEVELOPERS OR THE DISTRIBUTORS ON
THE ACCURACY OR THE RELIABILITY OF THIS PRODUCT.
THIS PRODUCT IS A PRACTICAL AND POWERFUL TOOL FOR STRUCTURAL
DESIGN. HOWEVER, THE USER MUST EXPLICITLY UNDERSTAND THE BASIC
ASSUMPTIONS OF THE SOFTWARE MODELING, ANALYSIS, AND DESIGN
ALGORITHMS AND COMPENSATE FOR THE ASPECTS THAT ARE NOT
ADDRESSED.
THE INFORMATION PRODUCED BY THE SOFTWARE MUST BE CHECKED BY
A QUALIFIED AND EXPERIENCED ENGINEER. THE ENGINEER MUST
INDEPENDENTLY VERIFY THE RESULTS AND TAKE PROFESSIONAL
RESPONSIBILITY FOR THE INFORMATION THAT IS USED.
Contents
1 Introduction
1.1 Organization 1-2
1.2 Recommended Reading/Practice 1-3
2 Design Prerequisites
2.1 Design Code 2-1
2.2 Units 2-1
2.3 Preferences 2-2
2.4 Overwrites 2-2
2.5 Composite Beam Properties 2-2
2.5.1 Beam Properties 2-2
2.5.2 Metal Deck and Slab Properties 2-4
2.5.3 Shear Stud Anchor Properties 2-5
2.5.4 Cover Plates 2-6
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Composite Beam Design AISC-LRFD 360-10

2.6 Beams Designed as Composite Beams 2-6
2.6.1 Frame Elements Designed by Default as
Composite Beams 2-7
2.6.2 Overwriting the Frame Design Procedure for a
Composite Beam 2-8
2.7 How the Program Optimizes Design Groups 2-9
2.8 Analysis Sections and Design Sections 2-12
2.9 Output Stations 2-13
2.10 Effective Width of the Concrete Slab 2-14
2.10.1 Location Where Effective Slab Width Is
Checked 2-14
2.10.2 Multiple Deck Types or Directions Along the
Beam Length 2-15
2.10.3 Effect of Diagonal Beams on Effective Slab
Width 2-19
2.10.4 Effect of Openings on Effective Slab Width 2-20
2.10.5 Effective Slab Width and Transformed
Section Properties 2-21
2.11 Beam Unbraced Length and Design Check
Locations 2-21
2.11.1 Determination of the Braced Points of a
Beam 2-22
2.11.2 User-Defined Unbraced Length of a Beam 2-23

2.12 Design Check Locations 2-24
2.13 Design Load Combinations 2-26
2.13.1 Special Live Load Patterning for
Cantilever Back Spans 2-28
2.13.2 Special Live Load Patterning for
Continuous Spans 2-30
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Contents
2.14 Beam Deflection and Camber 2-32
2.14.1 Deflection 2-32
2.14.2 Deflection Reported for Cantilever
Overhangs 2-33
2.14.3 Camber 2-33
2.15 Floor Vibration 2-34
2.15.1 Excitation Types 2-35
2.15.2 Design for Walking Excitation 2-35
2.15.3 Design for Rhythmic Excitation 2-39
2.15.4 Design for Sensitive Equipment 2-41
2.16 Distribution of Steel Headed Stud Anchors on a
Composite Beam 2-43
2.16.1 Composite Beam Segments 2-44
2.16.2 How the Program Distributes Steel Headed
Stud Anchors on a Beam 2-47
2.16.3 A Note About Multiple Design Load
Combinations 2-53
2.17 Number of Shear Studs that Fit in a Composite Beam
Segment 2-55
2.17.1 Solid Slab or Deck Ribs Oriented Parallel to Beam
Span 2-55
2.17.2 Deck Ribs Oriented Perpendicular to
Beam Span 2-59
2.18 User Defined Shear Connector Patterns 2-63
2.18.1 Specifying a User Defined Shear Connector
Pattern 2-63
2.18.2 Uniformly Spaced Shear Studs Over the
Length of the Beam 2-63
2.18.3 Additional Shear Studs in Specified
Sections of Beam 2-66
2.18.4 How the Program Checks a Beam
with User Defined Shear Studs 2-69
2.19 Transformed Section Moment of Inertia 2-70
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Composite Beam Design AISC-LRFD 360-10

2.19.1 Background 2-71
2.19.2 Properties of Steel Beam (Plus Cover Plate)
Alone 2-72
2.19.3 Properties of the Composite Section 2-75
2.20 Effective Moment of Inertia for Partial Composite
Action 2-82
2.21 Composite Plastic Moment Capacity for Positive
Bending 2-83
2.21.1 Location of the Plastic Neutral Axis 2-86
2.21.2 Plastic Moment Capacity for Positive
Bending 2-98
2.22 Composite Moment Capacity of a Partially
Composite Beam with a Plastic Stress Distribution 2-108
2.22.1 Location of the Plastic Neutral Axis 2-109
2.22.2 Determining the Effective Portion of the
Concrete Slab 2-111
2.22.3 Plastic Moment Capacity for Positive
Bending 2-113
3 Design Process
3.1 Notation 3-1
3.2 Design Methodology 3-16
3.3 Design Load Combinations 3-22
3.3.1 Strength Check for Construction Loads 3-22
3.3.2 Strength Check for Final Loads 3-23
3.3.3 Deflection Check for Final Loads 3-23
3.4 Compact and Noncompact Requirements 3-24
3.4.1 Limiting Width-to-Thickness Ratios for
Flanges 3-25
3.4.2 Limiting Width-to-Thickness Ratios for
Webs 3-26
3.4.3 Limiting Width-to-Thickness Ratios for
Cover Plates 3-27
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Contents
3.4.4 Slenderness Ratios for Lateral Torsional
Buckling 3-29
3.5 Composite Plastic Moment Capacity for Positive
Bending 3-30
3.6 Composite Section Elastic Moment Capacity 3-30
3.7 Moment Capacity for Steel Section Alone 3-31
3.7.1 Steel Beam Properties 3-32
3.7.2 Moment Capacity for a Doubly Symmetric
I-Beam 3-32
3.7.3 Moment Capacity for a Singly Symmetric
I-Beam 3-40
3.7.4 Moment Capacity for Channel Sections 3-47
3.8 Bending Checks 3-50
3.8.1 Bending Check Locations 3-50
3.8.2 Bending Check at Point of Maximum
Moment 3-50
3.8.3 Bending Check at Point Loads 3-51
3.9 Steel Anchors 3-51
3.9.1 Steel Headed Stud Anchor 3-52
3.9.2 Steel Channel Anchors 3-53
3.9.3 Horizontal Shear for Full Composite
Connection 3-53
3.9.4 Number of Shear Connectors 3-54
3.10 Beam Shear Capacity 3-55
3.10.1 Shear Capacity 3-55
3.10.2 Checking the Beam Shear 3-57
3.10.3 Limitations of Beam Shear Check 3-57
3.11 Deflection Check 3-58
3.12 Floor Vibration 3-58

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Composite Beam Design AISC-LRFD 360-10

Appendix A Preferences
Appendix B Overwrites
Bibliography

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