QTRUCTUREQ^ J S I X T H E D I T I O N L ^ J

Daniel L. Schodek

Martin Bechthold

PEARSONPrentice

Hall

Upper Saddle River, New JerseyColumbus, Ohio

Contents

PART I INTRODUCTORY CONCEPTS 1

1 Structures: An Overview 31.1 Introduction 31.2 General Types of Structures 4

1.2.1 Primary Classifications, 41.2.2 Primary Structural Elements, 9 y1.2.3 Primary Structural Units and Aggregations, 13

1.3 Basic Issues in the Analysis and Design of Structures 151.3.1 Fundamental Structural Phenomena, 151.3.2 Structural Stability, 171.3.3 Forces, Moments, and Stresses in Members: Tension, Compression,

Bending, Shear, Torsion, and Bearing, 191.3.4 The Basic Structural Analysis and Design Process, 23

1.4 Funicular Structures: Arches, Cables, and Related Forms 261.4.1 Basic Characteristics, 261.4.2 Structural Behavior, 28

1.5 Other Classifications 32Questions 33

2 Principles of Mechanics 352.12.2

Introduction 35Forces2.2.12.2.22.2.32.2.42.2.52.2.62.2.7

and Moments 36Analysis Objectives and Processes, 36Forces, 38Scalar and Vector Quantities, 38Parallelogram of Forces, 38Resolution and Composition of Forces, 40Statically Equivalent Systems, 42Moments, 42

VII

vin CONTENT:

2.3 Equilibrium 452.3.1 Equilibrium of a Particle, 452.3.2 Equilibrium of a Rigid Member, 462.3.3 Applied and Reactive Forces, 482.3.4 Complete Static Analyses, 63

2.4 Internal Forces and Moments 65

2.4.1 Axial Forces (Tension and Compression), 652.4.2 Shear and Moment, 662.4.3 Distribution of Shears and Moments, 682.4.4 Relations among Load, Shear, and Moment in Structures, 85

2.5 Introduction to Stresses 862.6 Mechanical Properties of Materials 90

2.6.1 Introduction, 902.6.2 General Load-Deformation Properties of Materials, 902.6.3 Elasticity, 912.6.4 Strength, 932.6.5 Other Material Properties, 95

2.7 Deformations in Tension and Compression Members 97

Questions 1003 Introduction to Structural Analysis and Design 102

3.1 Analysis and Design Criteria 103

3.2 Analysis and Design Process 105

3.3 Loads on Structures 1073.3.1 Introduction, 1073.3.2 Static Forces, 1083.3.3 Wind Loads, 1123.3.4 Earthquake Forces, 1153.3.5 Blast Loads, 1203.3.6 Load Combinations, 121

3.4 Modeling the Structure 122

3.5 Load Modeling and Reactions 126

Questions 140PART II ANALYSIS AND DESIGN OF STRUCTURAL ELEMENTS 142

4 Trusses 145

4.1 Introduction 145

4.2 General Principles 146

4.2.1 Triangulation, 146

4.2.2 Member Forces: Qualitative Analyses, 1484.3 Analysis of Trusses 151

4.3.1 Stability, 1514.3.2 Member Forces: General, 152

CONTENTS IX

4.3.3 Equilibrium of Joints, 1554.3.4 Equilibrium of Sections, 1634.3.5 Shears and Moments in Trusses, 1694.3.6 Statically Indeterminate Trusses, 1714.3.7 Use of Special Tensile Members: Cables, 1724.3.8 Space Trusses, 1744.3.9 Joint Rigidity, 1744.3.10 Computer-Aided Methods of Analysis, 176

4.4 Design of Trusses 7774.4.1 Objectives, 1774.4.2 Configurations, 1784.4.3 Depths of Trusses, 1884.4.4 Member Design Issues, 1894.4.5 Planar Versus Three-Dimensional Trusses, 195Questions 197

5 Funicular Structures: Cables and Arches 2015.1 Introduction to Funicular Structures 2015.2 General Principles of Funicular Shapes 2075.3 Analysis and Design of Cable Structures 203

5.3.1 Introduction, 2035.3.2 Suspended Cable Structures: Concentrated Loads, 2065.3.3 Suspended Cables: Uniformly Distributed Loads, 2115.3.4 Cables with Varying Support Levels, 2135.3.5 Cable Lengths, 2155.3.6 Wind Effects, 215

5.4 Design of Cable Structures 2165.4.1 Simple Suspension Cables, 2175.4.2 Double-Cable Systems, 2215.4.3 Cable-Stayed Structures, 222

5.5 Analysis and Design of Arches 2245.5.1 Masonry Arches, 2245.5.2 Parabolic Rigid Arches: Uniformly Distributed Loadings, 2255.5.3 Funicular Arches: Point Loadings, 2285.5.4 Design of Arch Structures, 230

s 5.5.5 Three-Hinged Arches, 2335.5.6 Comparisons Between Fixed Two-Hinged and Three-Hinged Arches, 240Questions 244

6 Beams 2466.1 Introduction 2466.2 General Principles 247

6.2.1 Beams in Buildings, 2476.2.2 Basic Stress Distributions, 249

CONTENTS

6.3 Analysis of Beams 2546.3.1 Bending Stresses, 2556.3.2 Lateral Buckling of Beams, 2706.3.3 Shear Stresses, 2726.3.4 Bearing Stresses, 2776.3.5 Torsion, 2786.3.6 Shear Center, 2806.3.7 Deflections, 2816.3.8 Principal Stresses, 2846.3.9 Finite-Element Analyses, 285

6.4 Design of Beams 2876.4.1 General Design Principles, 2876.4.2 Design of Timber Beams, 2946.4.3 Steel Beams, 2996.4.4 Reinforced-Concrete Beams: General Principles, 3046.4.5 Reinforced-Concrete Beams: Design and Analysis Principles, 3066.4.6 Reinforced-Concrete Beams: General Design Procedures, 3096.4.7 Prestressing and Posttensioning, 312Questions 316

Members in Compression: Columns 3197.1 Introduction 319

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7.2 General Principles 32013 Analysis of Compression Members 323

7.3.1 Short Columns, 3237.3.2 Long Columns, 325

1A Design of Compression Members 3357.4.1 General Design Principles, 3357.4.2 Column Sizes, 3417.4.3 Timber Columns, 3417.4.4 Steel Columns, 3427.4.5 Reinforced-Concrete Columns, 344Questions 345

Continuous Structures: Beams 3478.1 Introduction 3478.2 General Principles 347

8.2.1 Rigidity, 3508.2.2 Force Distributions, 350

8.3 Analysis of Indeterminate Beams 3518.3.1 Approximate Versus Exact Methods of Analysis, 3518.3.2 Approximate Methods of Analysis, 3528.3.3 Computer-Based Methods of Analysis 3548.3.4 Effects of Variations in Member Stiffness, 3558.3.5 Effects of Support Settlements, 358

CONTENTS . XI

8.3.6 Cable-Supported Beams, 3608.3.7 Effects of Partial-Loading Conditions, 363

8.4 Design of Indeterminate Beams 3648.4.1 Introduction, 3648.4.2 Design Moments, 3648.4.3 Shaping Continuous Beams, 3658.4.4 Use of Pinned Joints: Gerber Beams, 3678.4.5 Controlling Moment Distributions, 3708.4.6 Continuous Beams Made of Reinforced Concrete, 371Questions 372

9 Continuous Structures: Rigid Frames 3749.1 Introduction 3749.2 General Principles 3759.3 Analysis of Rigid Frames 378

9.3.1 Methods of Analysis, 3789.3.2 Importance of Relative Beam and Column

Stiffnesses, 3849.3.3 Sidesway, 3879.3.4 Support Settlements, 3909.3.5 Effects of Partial-Loading Conditions, 39Q.9.3.6 Multistory Frames, 3909.3.7 Vierendeel Frames, 391

9.4 Design of Rigid Frames 3959.4.1 Introduction, 3959.4.2 Selection of Frame Type, 3959.4.3 Design Moments, 3989.4.4 Shaping of Frames, 3999.4.5 Member and Connection Design, 4019.4.6 General Considerations, 401Questions 404

10 Plate and Grid Structures 40510.1 Introduction 40510.2 Grid Structures 40610.3 Plate Structures 409

10.3.1 One-Way Plate Structures, 40910.3.2 Two-Way Plate Structures, 412

10.4 Design of Two-Way Systems: General Objectives for Plate, Grid, andSpace-Frame Structures 420

10.5 Design of Reinforced-Concrete Two-Way Systems 42210.6 Space-Frame Structures 43110.7 Folded-Plate Structures 436

Questions 440

XII CONTENTS

11 Membrane and Net Structures 44211.1 Introduction 442

11.2 Pneumatic Structures 444

11.2.1 Background, 44411.2.2 Air-Supported Structures, 44611.2.3 Air-Inflated Structures, 45011.2.4 Other Considerations, 452

11.3 Analysis and Design of Net and Tent Structures 453

11.3.1 Curvatures, 45311.3.2 Support Conditions, 45411.3.3 Form Finding, 45511.3.4 Materials, 458

Questions 45912 Shell Structures 460

12.1 Introduction 460

12.2 Spherical Shell Structures 463

12.2.1 Introduction, 46312.2.2 Membrane Action in Shell Surfaces, 46512.2.3 Types of Forces in Spherical Shells^ 46612.2.4 Meridional Forces in Spherical Shells, 46812.2.5 Hoop Forces in Spherical Shells, 46912.2.6 Distribution of Forces, 47012.2.7 Concentrated Forces, 47112.2.8 Support Conditions: Tension and Compression Rings, 47112.2.9 Other Considerations, 475

12.3 Cylindrical Shells 476

12.4 Hyperbolic Paraboloid Shells 477

12.5 Free-Form Surfaces 479

Y2.6 Grid Shells 481

Questions 482

PART III PRINCIPLES OF STRUCTURAL DESIGN 485i

13 Structural Grids and Patterns: General Planning and Design 48713.1 Introduction 487

13.2 Common Grids 488

13.3 General Characteristics of Structural Hierarchies 491

13.3.1 One-Way Systems, 49113.3.2 Two-Way Systems, 49413.3.3 Relation to Roof Shape, 49613.3.4 Relations Between Span Length and Structure Type, 498

CONTENTS XIII

13.3.5 Relations Between Loading Type and Structure Type, 50213.3.6 Concentrated Versus Distributed Structures, 503

13.4 Design Issues 50413.4.1 Relation of Structure to Functional Spaces, 50413.4.2 Space-Forming Characteristics, 50713.4.3 One-Way Versus Two-Way Systems: Impact of Grid Geometry and

Dimensions, 51013.4.4 Effects of Local Geometrical Conditions, 51213.4.5 Varying Support Locations, 51513.4.6 Nonuniform Grids, 51613.4.7 Multistory Buildings: Dependency of Grid Spacing and Floor-to-Floor

Height, 51713.4.8 Accommodating Large Spaces, 51813.4.9 Meeting of Structural Grids, 52013.4.10 Accommodating Special Conditions, 52413.4.11 Other Constraints, 527

14 Structural Systems: Design for Lateral Loadings 52914.1 Lateral Forces: Effects on the Design of Structures 529

14.1.1 Basic Design Issues, 52914.1.2 Multistory Construction, 544

14.2 Earthquake Design Considerations 54914.2.1 General Principles, 54914.2.2 General Design and Planning Considerations, 55114.2.3 General Characteristics of Earthquake-Resistant Structures, 55414.2.4 Materials, 55614.2.5 Stiffness Issues, 55714.2.6 Nonstructural Elements, 55814.2.7 Base Isolation Systems and Other Techniques, 559Questions 560

15 Structural Systems: Constructional Approaches 56115.1 Introduction 56715.2 Wood Construction 56715.3 Reinforced-Concrete Construction 56715.4 Steel Construction 57315.5 Foundations and Retaining Walls 576

Questions 57916 Structural Connections 580

16.1 Introduction 58016.2 Basic Joint Geometries 58016.3 Basic Types of Connectors 557

76J.7 Bolts and Rivets, 58316.3.2 Welded Joints, 587Questions 588

XIV CONTEN1

Appendices 58

1 Conversions 5892 Nonconcurrent Force Systems 5893 Moments of Distributed Loads 5894 Centroids 5905 Moments of Inertia 592

A5.7 General Formulation, 592A.5.2 Parallel-Axis Theorem, 594A.5.3 Negative Areas, 595

6 Bending Stresses in Beams 5967 Shearing Stresses in Beams 5978 MomentTCurvature Relations 5999 Deflections 600

A.9.1 General Differential Equation, 600A.9.2 Deflections: Double-Integration Method, 601

10 Moment-Area Theorems: Slopes and Deflections 60211 Other Methods of Analyzing Indeterminate Structures 60212 Reinforced-Concrete Beams: Detailed U.S. Design Procedures 60413 Critical Buckling Loads for Compression Members 60814 Computer-Based Methods of Analysis: Force and Matrix-Displacement

Techniques 60915 Computer-Based Methods of Analysis: Finite-Element Techniques 61716 Properties 61917 Typical Material Properties 620

Index 61