Abi AghayereProfessorDepartment of Civil, Architectural, and Environmental EngineeringDrexel University

NiNth EditioN

Reinforced Concrete Design

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Library of Congress Cataloging-in-Publication Data

Names: Aghayere, Abi O., author. Title: Reinforced concrete design / Abi Aghayere, Professor, Department of Civil, Architectural, and Environmental Engineering, Drexel University.Description: Ninth edition. | Upper Saddle River, New Jersey : Pearson Education, Inc., 2018. | Includes bibliographical references and index.Identifiers: LCCN 2017056582| ISBN 9780134715353 | ISBN 0134715357Subjects: LCSH: Reinforced concrete.Classification: LCC TA444 .L44 2018 | DDC 624.1/8341--dc23 LC record available at https://lccn.loc.gov/2017056582

1 17

ISBN 10: 0-13-471535-7ISBN 13: 978-0-13-471535-3

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NOTICE TO THE READER

T he information contained in this book has been prepared in accordance with recognized engineering principles and is for general in-

formation only. Although it is believed to be accurate, this information should not be used for any specific application without competent professional examina-tion and verification of its accuracy, suitability, and

applicability by a licensed professional engineer, ar-chitect, or designer. The authors and publisher of this book make no warranty of any kind, expressed or im-plied, with regard to the material contained in this book nor shall they be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the reader’s use of or reliance on this material.

iii

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To the cherished memory of my mother, Regina Ekeneza-Obasogie, and my great-grand mother, Aghayubini Osawe

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updated. Working on the design project helps the student appreciate how and where the individual re-inforced concrete elements covered in the different chapters fit within the context of a real life building project. Thus, they can see how what they have learned is readily applicable to, and usable in, the real world of engineering and construction. Answers to selected problems are furnished at the back of the text.

This text is suitable for any undergraduate con-crete design course which would typically include topics from Chapters 1, 2, 3, 4, 5, 6, 7, and parts of Chapters 9 and 10. The remaining topics and chapters could make up a significant portion of a second under-graduate concrete design course. This text covers more topics than those required in the Concrete I course, and many of the topics required in the Foundation Design course, of the Basic Education for Structural Engineers Curriculum published by the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE), the National Council of Structural Engineering Associations (NCSEA), and the Council of American Structural Engineers (CASE).

Throughout the nine editions, the text content has maintained primarily a fundamental and practice-oriented approach to the design and analysis of rein-forced concrete structural members using numerous examples and a step-by-step solution format. In ad-dition, there are chapters that provide a conceptual approach on such topics as prestressed concrete and detailing of reinforced concrete structures. The metric system (SI) is introduced in Appendix C with several example problems.

Form design is an important consideration in most structural design problems involving concrete members, and Chapter 12 illustrates procedures for the design of job-built forms for slabs, beams, and columns. Appropriate tables are included that will expedite the design process. In Chapter 14, we intro-duce the reader to several practical considerations

T he primary objective of Reinforced Concrete Design, ninth edition, remains the same as that of the previous editions that were co-authored

with George F. Limbrunner, who is now retired: to provide a basic and thorough understanding of the strength and behavior of reinforced concrete members and reinforced concrete structural systems.

With the recent changes in the ACI 318 Code, and relevant reinforced concrete research and litera-ture continuing to become available at a rapid rate, it is the intent of this book to translate this vast amount of information and data into an integrated source that reflects the latest information available. This book is intended to help the reader understand the funda-mentals of reinforced concrete design and behavior, and good practices in the industry. It will be useful to students in undergraduate civil and architectural engi-neering programs, and engineering technology and ar-chitecture programs. In addition, practicing structural engineers and engineers preparing for the licensure exams will find this text to be a helpful and practical resource.

This ninth edition has been prepared with the primary objective of updating its contents to conform to the latest Building Code Requirements for Structural Concrete (ACI 318-14) of the American Concrete Institute. The ACI 318-14 is a complete reorganiza-tion of the Code compared to previous editions of the Code, in addition to incorporating a number of technical changes. Throughout the text, frequent references are made to the pertinent sections of the ACI Code. Because the ACI Code serves as the de-sign standard in the United States, it is strongly rec-ommended that the Code be used as a companion publication to this book.

In addition to the necessary changes to conform to the new code, some sections have been edited, new sec-tions have been added, and the student design project problems have been enhanced and several drawings

PREFACE

v

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and rules of thumb for the design of reinforced con-crete beams, girders, columns and one-way slabs, and methods for strengthening existing reinforced con-crete structures.

NEW TO THIS EDITION• The entire text has been revised to conform to the

latest ACI Code: ACI 318-14.• The design of concrete mixes and admixtures is

discussed in Chapter 1 and an introduction to grav-ity load distribution (tributary areas and tributary width) and concrete slab systems is presented.

• The design of slab-on-grade is included in Chapter 2.• The design of corbels and brackets is included in

Chapter 4.• Structural integrity reinforcement is presented in

Chapter 5 and more examples on the development of reinforcement have been added to the chapter.

• Two-way slab design using the direct design meth-od is covered in Chapter 6 together with an intro-duction to the equivalent frame method.

• In Chapter 7, the procedures for calculating the long-term deflections of continuous beams and girders are included, in addition to a new example on the long-term deflection of a continuous T-beam. Deflection control measures are discussed and the design of concrete floor systems for vibrations is also included in Chapter 7.

• The design of columns subject to axial load plus bi-axial bending, the moment magnification factor, and the design of slender columns in non-sway or braced frames are introduced in Chapter 9.

• A discussion of the types of information contained in a geotechnical report and the design of eccentri-cally loaded spread footings with a new example to illustrate the design procedure are presented in Chapter 10.

• The design of pile caps and deep beams using the strut-and-tie method is covered in Chapter 10.

• A new section on diaphragms, chords, and drag struts is included in Chapter 14. Additional sections added to this chapter include one-way slabs subject-ed to concentrated loads, fire resistance of structural concrete, concrete pour strips to mitigate shrinkage cracks, concrete specifications, and load testing of existing structures.

• A second student design project problem has been added in Chapter 14.

This book has been thoroughly tested over the years in engineering, architecture, and engineering technology programs, and should serve as a valu-able design guide and resource for engineering and architectural students, technologists, and design

engineers. In addition, it will aid engineers and ar-chitects preparing for state licensing examinations for professional registration.

AcknowledgmentsThanks are due to George Limbrunner—the founding co- author of this text since 1977, and with whom I was co-author for the sixth through the eighth editions—for the rich legacy and practical imprint he left on this text.

I would also like to thank the peer reviewers for the previous editions and particularly those who did the review for this edition for their many valued contributions. We are excited about continuing the practice-oriented and easy-to-understand emphasis of this textbook while introducing some new topics of in-terest based on the feedback we have received on the previous editions.

As in the past, appreciation is extended to our stu-dents, past and present, and our colleagues, whose constructive feedback and enthusiasm have provided encouragement for this edition. Special thanks to Jason Vigil, S.E., P.E., for his invaluable input and his immense help in preparing the figures for this edition. Thanks are due as well to Ben Okorosobo, P.Eng., consulting structural engineer, for his helpful insights during the preparation of this text. I am also indebted to the late University Professor James G. MacGregor for his men-torship during and after my doctoral studies at the University of Alberta.

I’m grateful to my forever-bride, Josephine, for her enduring support and patience, and to my children—Osa, Ito, Odosa, and Eghosa—for their con-tinuous encouragement. Finally, I am most grateful to Almighty God for His amazing grace and strength that made this project possible.

Download Instructor Resources from the Instructor Resource CenterTo access supplementary materials online, instruc-tors need to request an instructor access code. Go to www.pearsonhighered.com/irc to register for an in-structor access code. Within 48 hours of registering, you will receive a confirming e-mail including an in-structor access code. Once you have received your code, locate your text in the online catalog and click on the Instructor Resources button on the left side of the catalog product page. Select a supplement, and a login page will appear. Once you have logged in, you can access instructor material for all Pearson textbooks. If you have any difficulties accessing the site or down-loading a supplement, please contact Customer Ser-vice at http://support.pearson.com/getsupport

Abi AghayerePhiladelphia, PA

vi Preface

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2-5 Flexural Strength of Rectangular Beams 24

2-6 Equivalent Stress Distribution 25

2-7 Balanced, Brittle, and Ductile Failure Modes 27

2-8 Ductility Requirements 28

2-9 Strength Requirements 30

2-10 Rectangular Beam Analysis for Moment (Tension Reinforcement Only) 31

2-11 Summary of Procedure for Rectangular Beam Analysis for FMn (Tension Reinforcement Only) 34

2-12 Slabs: Introduction 34

2-13 One-Way Slabs: Analysis for Moment 34

2-14 Rectangular Beam Design for Moment (Tension Reinforcement Only) 37

2-15 Summary Of Procedure for Rectangu-lar Reinforced Concrete Beam Design for Moment (Tension Reinforcement Only) 41

2-16 Design of One-Way Slabs for Moment (Tension Reinforcement Only) 41

2-17 Summary of Procedure for Design of One-Way Slabs for Moment (To Satisfy ACI Minimum Thickness, h) 43

2-18 Slabs-On-Grade 43

References 46

Problems 46

Chapter 1MATERIALS AND MECHANICS OF BENDING, AND CONCRETE SLAB SYSTEMS 1

1-1 Concrete 1

1-2 The ACI Building Code 1

1-3 Cement and Water 1

1-4 Aggregates 1

1-5 Concrete Mixes 2

1-6 Concrete in Compression 3

1-7 Concrete in Tension 5

1-8 Reinforcing Steel 5

1-9 Concrete Cover 8

1-10 Beams: Mechanics of Bending Review 8

1-11 Concrete Slab Systems 13

1-12 Gravity Load Distribution in Concrete Slab Systems 14

References 16

Problems 17

Chapter 2RECTANGULAR REINFORCED CONCRETE BEAMS AND SLABS: TENSION STEEL ONLY 21

2-1 Introduction 21

2-2 Analysis and Design Method 21

2-3 Behavior Under Load 22

2-4 Strength Design Method Assumptions 23

CONTENTS

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viii Contents

Chapter 5DEVELOPMENT, SPLICES, AND SIMPLE-SPAN BAR CUTOFFS 104

5-1 Bond Stress and Development Length: Introduction 104

5-2 Development Length: Tension Bars 106

5-3 Development Length: Compression Bars 111

5-4 Development Length: Standard Hooks in Tension 112

5-5 Development of Web Reinforcement 115

5-6 Splices 117

5-7 Tension Splices 117

5-8 Compression Splices 117

5-9 Simple-Span Bar Cutoffs and Bends 118

5-10 Code Requirements for Development of Positive Moment Steel at Simple Supports 122

5-11 Structural Integrity Reinforcement– Beams 125

References 126

Problems 126

Chapter 6CONTINUOUS ONE-WAY AND TWO-WAY FLOOR SYSTEMS 130

6-1 Introduction 130

6-2 Continuous-Span Bar Cutoffs 132

6-3 Design of Continuous One-Way Floor Systems 133

6-4 Analysis and Design of Continuous Two-Way Slabs 145

References 180

Problems 180

Chapter 7SERVICEABILITY 183

7-1 Introduction 183

7-2 Deflections 183

7-3 Calculation of Icr 184

7-4 Immediate Deflection 186

7-5 Long-Term Deflection 186

Chapter 3REINFORCED CONCRETE BEAMS: T-BEAMS, L-BEAMS, AND DOUBLY REINFORCED BEAMS 51

3-1 T-Beams and L-Beams: Introduction 51

3-2 T-Beam and L-Beam Analysis 53

3-3 Analysis of Beams Having Irregular Cross Sections 56

3-4 T-Beam and L-Beam Design (for Moment) 57

3-5 Summary of Procedure for Analysis of T-Beams and L-Beams (for Moment) 60

3-6 Summary of Procedure for Design of T-Beams and L-Beams (for Moment) 61

3-7 Doubly Reinforced Beams: Introduction 62

3-8 Doubly Reinforced Beam Analysis for Moment (Condition I) 62

3-9 Doubly Reinforced Beam Analysis for Moment (Condition II) 65

3-10 Summary of Procedure for Analysis of Doubly Reinforced Beams (for Moment) 67

3-11 Doubly Reinforced Beam Design for Moment 68

3-12 Summary of Procedure for Design of Doubly Reinforced Beams (for Moment) 69

3-13 Additional Code Requirements for Doubly Reinforced Beams 70

Problems 71

Chapter 4

SHEAR AND TORSION 75

4-1 Introduction 75

4-2 Shear Reinforcement Design Requirements 76

4-3 Shear Analysis Procedure 78

4-4 Stirrup Design Procedure 79

4-5 Torsion of Reinforced Concrete Members 86

4-6 Corbels and Brackets 94

References 99

Problems 99

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Contents ix

9-6 Summary of Procedure for Analysis and Design of Short Columns with Small Eccentricities 241

9-7 The Load-Moment Relationship 241

9-8 Columns Subjected to Axial Load at Large Eccentricity 242

9-9 F Factor Considerations 242

9-10 Analysis of Short Columns: Large Eccentricity 243

9-11 Biaxial Bending 250

9-12 The Slender Column 252

9-13 Concrete Column Schedule 256

References 257

Problems 257

Chapter 10

FOUNDATIONS 260

10-1 Introduction 260

10-2 The Geotechnical Report 261

10-3 Wall Footings 262

10-4 Wall Footings Under Light Loads 267

10-5 Individual Reinforced Concrete Footings for Columns 267

10-6 Square Reinforced Concrete Footings 270

10-7 Rectangular Reinforced Concrete Footings 273

10-8 Eccentrically Loaded Footings 277

10-9 Combined Footings 282

10-10 Cantilever or Strap Footings 284

10-11 Analysis and Design of Mat Foundations 286

10-12 Deep Foundations–Piles, Drilled Shaft (Caissons), and Pile Caps 287

10-13 Strut-and-Tie Models for Pile Caps and Deep Beams 292

References 300

Problems 301

Chapter 11 PRESTRESSED CONCRETE FUNDAMENTALS 303

11-1 Introduction 303

11-2 Design Approach and Basic Concepts 303

7-6 Procedure for Calculating the Deflection of Simply Supported and Continuous Beams and Slabs 189

7-7 Procedure for Calculating the Deflection of Continuous Girders 190

7-8 Deflection Control Measures in Reinforced Concrete Structures 193

7-9 Crack Control 194

7-10 Floor Vibrations 195

7-11 Gross and Cracked Section Properties of Concrete Sections 197

References 198

Problems 198

Chapter 8WALLS 200

8-1 Introduction 200

8-2 Lateral Forces on Retaining Walls 201

8-3 Design of Reinforced Concrete Cantilever Retaining Walls 204

8-4 Design Considerations for Bearing Walls 219

8-5 Design Considerations for Basement Walls 221

8-6 Lateral Load Resisting Systems in Concrete Buildings 221

8-7 Concrete Moment Frames 222

8-8 Shear Walls 223

References 231

Problems 231

Chapter 9 COLUMNS 234

9-1 Introduction 234

9-2 Strength of Reinforced Concrete Columns: Small Eccentricity 235

9-3 Code Requirements Concerning Column Details 236

9-4 Analysis of Short Columns: Small Eccentricity 238

9-5 Design of Short Columns: Small Eccentricity 239

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x Contents

Chapter 14 PRACTICAL CONSIDERATIONS IN THE DESIGN OF REINFORCED CONCRETE BUILDINGS 360

14-1 Introduction 360

14-2 Rules of Thumb and Practical Considerations for Reinforced Concrete Design 360

14-3 Approximate Moments and Shears in Continuous Girders 362

14-4 Strengthening and Rehabilitation of Existing Reinforced Concrete Structures 364

14-5 Diaphragms, Drag Struts, and Chords 369

14-6 One-Way Slabs Subjected to Concentrated Loads 371

14-7 Load Testing of Structures 373

14-8 Closure or Pour Strips in Reinforced Concrete Floors 375

14-9 Fire Resistance of Concrete Structural Elements 376

14-10 Analysis and Design of Edge-Supported Two-Way Slabs on Stiff Supports 377

14-11 Cast-In Place Concrete Specifications 379

14-12 Student Design Projects 381

References 385

APPENDIX A TABLES AND DIAGRAMS 386

APPENDIX B SUPPLEMENTARY AIDS AND GUIDELINES 403

B-1 ACCURACY FOR COMPUTATIONS FOR REINFORCED CONCRETE 403

B-2 FLOW DIAGRAMS 403

APPENDIX C METRICATION 408

C-1 THE INTERNATIONAL SYSTEM OF UNITS (SI) 408

C-2 SI STYLE AND USAGE 410

C-3 CONVERSION FACTORS 411

REFERENCES 416

APPENDIX D ANSWERS TO SELECTED PROBLEMS 417

INDEX 419

11-3 Stress Patterns in Prestressed Concrete Beams 305

11-4 Prestressed Concrete Materials 306

11-5 Analysis of Rectangular Prestressed Concrete Beams 307

11-6 Alternative Methods of Elastic Analysis: Load Balancing Method 310

11-7 Flexural Strength Analysis 313

11-8 Notes on Prestressed Concrete Design 315

References 315

Problems 315

Chapter 12

CONCRETE FORMWORK 317

12-1 Introduction 317

12-2 Formwork Requirements 317

12-3 Formwork Materials and Accessories 318

12-4 Loads and Pressures on Forms 319

12-5 The Design Approach 321

12-6 Design of Formwork for Slabs 326

12-7 Design of Formwork for Beams 331

12-8 Wall Form Design 335

12-9 Forms for Columns 339

References 342

Problems 342

Chapter 13 DETAILING REINFORCED CONCRETE STRUCTURES 344

13-1 Introduction 344

13-2 Placing or Shop Drawings 345

13-3 Marking Systems and Bar Marks 345

13-4 Schedules 352

13-5 Fabricating Standards 352

13-6 Bar Lists 353

13-7 Extras 354

13-8 Bar Supports and Bar Placement 355

13-9 Computer Detailing 356

References 359

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