Reinforced Concrete Design

CONTENTS......Page 1
1.1 INTRODUCTION......Page 15
1.2.1 Plain Concrete......Page 18
1.2.2 Reinforced Concrete......Page 19
1.3 OBJECTIVES OF STRUCTURAL DESIGN......Page 21
1.4 REINFORCED CONCRETE CONSTRUCTION......Page 22
1.6 REINFORCED CONCRETE BUILDINGS......Page 23
1.6.1 Floor Systems......Page 25
1.6.2 Vertical Framing System......Page 31
1.6.3 Lateral Load Resisting Systems......Page 33
1.7 STRUCTURAL ANALYSIS AND DESIGN......Page 35
1.8.2 Basic Code for Design......Page 36
1.8.5 Other Related Codes......Page 37
REFERENCES......Page 38
2.1.1 Concrete Technology......Page 39
2.2.1 Portland Cements......Page 40
2.2.2 Other Cements......Page 42
2.3 AGGREGATE......Page 43
2.3.1 Aggregate Properties and Tests......Page 44
2.3.2 Grading Requirements of Aggregate......Page 45
2.4 WATER......Page 46
2.4.1 Water Content and Workability of Concrete......Page 47
2.4.2 Water-Cement Ratio and Strength......Page 48
2.4.3 Water for Curing......Page 49
2.5 ADMIXTURES......Page 50
2.5.2 Types of Mineral Admixtures......Page 51
2.6 GRADE OF CONCRETE......Page 52
2.6.1 Characteristic Strength......Page 53
2.7.1 Nominal Mix Concrete......Page 54
2.7.2 Design Mix Concrete......Page 55
2.8 BEHAVIOUR OF CONCRETE UNDER UNIAXIAL COMPRESSION......Page 56
2.8.1 Influence of Size of Test Specimen......Page 57
2.8.2 Stress-Strain Curves......Page 59
2.8.3 Modulus of Elasticity and Poisson’s Ratio......Page 60
2.8.4 Influence of Duration of Loading on Stress-Strain Curve......Page 64
2.9 BEHAVIOUR OF CONCRETE UNDER TENSION......Page 65
2.9.2 Splitting Tensile Strength......Page 66
2.9.3 Stress-Strain Curve of Concrete in Tension......Page 67
2.10.2 Influence of Shear Stress......Page 68
2.11.1 Time-Dependent Behaviour under Sustained Loading......Page 70
2.11.2 Effects of Creep......Page 71
2.12.1 Shrinkage......Page 72
2.13 DURABILITY OF CONCRETE......Page 74
2.13.1 Environmental Exposure Conditions and Code Requirements......Page 76
2.13.3 Chemical Attack on Concrete......Page 78
2.14 REINFORCING STEEL......Page 80
2.14.1 Types, Sizes and Grades......Page 81
2.14.2 Stress-Strain Curves......Page 82
2.15 LIST OF RELEVANT INDIAN STANDARDS......Page 85
Standards on Concrete......Page 86
REVIEW QUESTIONS......Page 87
REFERENCES......Page 89
3.1.1 Design Considerations......Page 91
3.1.2 Design Philosophies......Page 92
3.2 WORKING STRESS METHOD (WSM)......Page 93
3.4.1 Uncertainties in Design......Page 94
3.4.2 Classical Reliability Models......Page 96
3.4.4 Levels of Reliability Methods......Page 98
3.5.2 Multiple Safety Factor Formats......Page 99
3.5.4 Partial Safety Factor Format......Page 100
3.6.1 Characteristic Strengths and Loads......Page 101
3.6.3 Partial Safety Factors for Loads......Page 102
3.6.4 Design Stress-Strain Curve for Concrete......Page 103
3.6.5 Design Stress-Strain Curve for Reinforcing Steel......Page 104
REVIEW QUESTIONS......Page 107
REFERENCES......Page 108
4.1.1 Two Kinds of Problems : Analysis and Design......Page 109
4.1.2 Bending Moments in Beams from Structural Analysis......Page 110
4.2.2 Distribution of Stresses......Page 111
4.3 LINEAR ELASTIC ANALYSIS OF COMPOSITE SECTIONS......Page 113
4.3.1 Distribution of Strains and Stresses......Page 114
4.4.1 Modular Ratio in Reinforced Concrete......Page 115
4.4.2 Transformed Area of Reinforcing Steel......Page 116
EXAMPLE 4.1......Page 117
4.5 FLEXURAL BEHAVIOUR OF REINFORCED CONCRETE......Page 119
4.5.2 Linear Elastic Cracked Phase......Page 121
4.5.3 Stages Leading to Limit State of Collapse......Page 122
4.6.1 Stresses in Singly Reinforced Rectangular Sections......Page 126
EXAMPLE 4.2......Page 128
4.6.2 Permissible Stresses......Page 129
4.6.3 Allowable Bending Moment......Page 130
EXAMPLE 4.3......Page 135
4.6.4 Analysis of Singly Reinforced Flanged Sections......Page 136
EXAMPLE 4.4......Page 140
EXAMPLE 4.5......Page 141
4.6.5 Analysis of Doubly Reinforced Sections......Page 142
EXAMPLE 4.6......Page 144
EXAMPLE 4.7......Page 145
4.7 ANALYSIS AT ULTIMATE LIMIT STATE......Page 147
4.7.1 Assumptions in Analysis......Page 148
4.7.2 Limiting Depth of Neutral Axis......Page 149
4.7.3 Analysis of Singly Reinforced Rectangular Sections......Page 151
EXAMPLE 4.9......Page 159
EXAMPLE 4.11......Page 160
4.7.4 Analysis of Singly Reinforced Flanged Sections......Page 161
EXAMPLE 4.12......Page 165
EXAMPLE 4.13......Page 166
4.7.5 Analysis of Doubly Reinforced Sections......Page 168
EXAMPLE 4.15......Page 170
EXAMPLE 4.16......Page 172
4.7.6 Balanced Doubly Reinforced Sections......Page 173
4.8 ANALYSIS OF SLABS AS RECTANGULAR BEAMS......Page 175
4.8.1 Transverse Moments in One-way Slabs......Page 176
EXAMPLE 4.17......Page 177
REVIEW QUESTIONS......Page 178
PROBLEMS......Page 179
REFERENCES......Page 182
5.1 INTRODUCTION......Page 184
5.2.1 Concrete Cover......Page 185
5.2.2 Spacing of Reinforcing Bars......Page 187
5.2.3 Minimum and Maximum Areas† of Flexural Reinforcement......Page 189
5.3 REQUIREMENTS FOR DEFLECTION CONTROL......Page 190
5.3.1 Deflection Control by Limiting Span/Depth Ratios......Page 191
5.3.2 Code Recommendations for Span/Effective Depth Ratios......Page 192
5.4.1 General Guidelines for Beam Sizes......Page 194
5.4.3 Deep Beams and Slender Beams......Page 195
5.5 DESIGN OF SINGLY REINFORCED RECTANGULAR SECTIONS......Page 196
5.5.1 Fixing Dimensions of Rectangular Section......Page 197
5.5.2 Determining Area of Tension Steel......Page 198
SOLUTION......Page 200
EXAMPLE 5.2......Page 202
SOLUTION......Page 203
5.6.1 Simplified Structural Analysis ( Use of Moment Coefficients......Page 204
5.6.2 Design Procedure......Page 207
EXAMPLE 5.3......Page 208
SOLUTION......Page 209
5.7.1 Design Formulas......Page 212
5.7.2 Design Procedure for Given Mu......Page 214
EXAMPLE 5.4......Page 215
5.8.1 Transverse Reinforcement in Flange......Page 218
5.8.2 Design Procedure......Page 219
SOLUTION......Page 221
SOLUTION......Page 223
5.9.1 Theoretical Bar Cut-off Points......Page 225
5.9.2 Restrictions on Theoretical Bar Cut-off Points......Page 227
5.9.3 Code Requirements......Page 229
EXAMPLE 5.7......Page 234
REVIEW QUESTIONS......Page 236
PROBLEMS......Page 237
REFERENCES......Page 238
6.1 INTRODUCTION......Page 240
6.2 SHEAR STRESSES IN HOMOGENEOUS RECTANGULAR BEAMS......Page 241
6.3.1 Modes of Cracking......Page 243
6.3.2 Shear Transfer Mechanisms......Page 245
6.3.3 Shear Failure Modes......Page 247
6.4.1 Members with Uniform Depth......Page 249
6.4.2 Members with Varying Depth......Page 250
6.5 CRITICAL SECTIONS FOR SHEAR DESIGN......Page 251
6.6.1 Design Shear Strength of Concrete in Beams......Page 253
6.6.2 Design Shear Strength of Concrete in Slabs......Page 255
6.6.3 Influence of Axial Force on Design Shear Strength......Page 256
6.7.1 Types of Shear Reinforcement......Page 257
6.7.2 Factors Contributing to Ultimate Shear Resistance......Page 258
6.7.3 Limiting Ultimate Shear Resistance......Page 259
6.7.4 Shear Resistance of Web Reinforcement......Page 260
6.7.5 Influence of Shear on Longitudinal Reinforcement......Page 262
6.8 ADDITIONAL COMMENTS ON SHEAR REINFORCEMENT DESIGN......Page 264
6.9.1 Shear-Friction......Page 266
6.9.2 Recommendation for Interface Shear Transfer......Page 269
6.10.1 Shear along Horizontal Planes......Page 271
SOLUTION......Page 272
SOLUTION......Page 275
SOLUTION......Page 276
REVIEW QUESTIONS......Page 278
REFERENCES......Page 281
7.2 EQUILIBRIUM TORSION AND COMPATIBILITY TORSION......Page 283
7.2.2 Compatibility Torsion......Page 284
7.2.3 Estimation of Torsional Stiffness......Page 286
7.3.1 Behaviour of Plain Concrete......Page 287
7.3.2 Behaviour of Concrete with Torsional Reinforcement......Page 289
7.4.1 Design Torsional Strength without Torsional Reinforcement......Page 290
7.4.2 Design Torsional Strength with Torsional Reinforcement......Page 293
7.4.3 Design Strength in Torsion Combined with Flexure......Page 296
7.4.4 Design Strength in Torsion Combined with Shear......Page 298
SOLUTION......Page 300
SOLUTION......Page 301
SOLUTION......Page 302
Design of longitudinal reinforcement......Page 305
REVIEW QUESTIONS......Page 307
REFERENCES......Page 310
8.1.1 Mechanisms of Bond Resistance......Page 311
8.1.3 Two Types of Bond......Page 312
8.2 FLEXURAL BOND......Page 313
8.2.1 Effect of Flexural Cracking on Flexural Bond Stress......Page 314
8.3 ANCHORAGE (DEVELOPMENT) BOND......Page 315
8.3.1 Development Length......Page 316
8.4.1 Bond Failure Mechanisms......Page 317
8.4.2 Bond Tests......Page 319
8.5.1 Flexural Bond......Page 321
8.5.3 Bends, Hooks and Mechanical Anchorages......Page 322
8.6.1 Lap Splices......Page 324
8.6.2 Welded Splices and Mechanical Connections......Page 326
SOLUTION......Page 327
EXAMPLE 8.2......Page 329
REVIEW QUESTIONS......Page 330
REFERENCES......Page 332
9.1.1 Approximations in Structural Analysis......Page 333
Redistribution......Page 336
9.2 GRAVITY LOAD PATTERNS FOR MAXIMUM DESIGN MOMENTS......Page 337
9.2.1 Design Moments in Beams......Page 338
9.2.2 Design Moments in Columns......Page 339
9.3.2 Substitute Frame Method of Frame Analysis for Gravity Loads......Page 340
9.3.3 Simplified Methods for Lateral Load Analysis......Page 343
9.4 PROPORTIONING OF MEMBER SIZES FOR PRELIMINARY DESIGN......Page 344
JUNCTIONS......Page 347
9.7.1 Limit Analysis......Page 351
9.7.2 Moment Redistribution......Page 354
9.7.3 Code Recommendations for Moment Redistribution......Page 358
EXAMPLE 9.1......Page 363
EXAMPLE 9.2......Page 366
REVIEW QUESTIONS......Page 371
REFERENCES......Page 373
10.1 INTRODUCTION......Page 375
10.2.1 Deflection Limits......Page 376
10.2.2 Difficulties in Accurate Prediction of Deflections......Page 377
10.3.1 Deflections by Elastic Theory......Page 378
10.3.2 Effective Flexural Rigidity......Page 379
10.3.3 Tension Stiffening Effect......Page 380
10.3.4 Effective Second Moment of Area Formulation......Page 382
10.3.5 Average Ieff for Continuous Spans......Page 384
10.3.6 Effective Curvature Formulation......Page 386
SOLUTION......Page 388
Maximum short-term deflection (uncracked section)......Page 389
Maximum short-term deflection (cracked section)......Page 390
10.3.7 Additional Short-Term Deflection Due to Live Loads Alone......Page 391
SOLUTION......Page 392
SOLUTION......Page 393
SOLUTION......Page 395
10.4 LONG-TERM DEFLECTION......Page 398
10.4.1 Deflection Due to Differential Shrinkage......Page 399
10.4.2 Deflection Due to Creep......Page 402
10.4.3 Deflection Due to Temperature Effects......Page 405
SOLUTION......Page 406
SOLUTION......Page 408
10.5.1 Cracking in Reinforced Concrete Members......Page 409
10.5.3 Factors Influencing Crack-widths......Page 411
10.5.4 Estimation of Flexural Crack-width......Page 413
SOLUTION......Page 417
SOLUTION......Page 420
10.5.5 Estimation of Crack-width under Direct and Eccentric Tension......Page 423
SOLUTION......Page 425
Drying Shrinkage......Page 427
Methods of Crack Control and Crack-width Estimation......Page 428
REVIEW QUESTIONS......Page 430
REFERENCES......Page 433
11.1.1 One-Way and Two-Way Actions of Slabs......Page 435
11.1.2 Torsion in Two-Way Slabs......Page 437
Supported Slabs......Page 438
11.2.2 Methods of Analysis......Page 440
11.2.3 Uniformly Loaded and Simply Supported Rectangular Slabs......Page 441
11.2.4 Uniformly Loaded ‘Restrained’ Rectangular Slabs......Page 445
11.2.5 Shear Forces in Uniformly Loaded Two-Way Slabs......Page 453
SOLUTION......Page 454
Check for deflection control......Page 456
SOLUTION......Page 457
EXAMPLE 11.3......Page 459
SOLUTION......Page 460
11.2.6 Design of Circular, Triangular and Other Slabs......Page 466
SOLUTION......Page 470
SOLUTION......Page 471
11.3.1 Behaviour of Beam-Supported Slabs......Page 472
on Stiff Beams......Page 473
11.3.3 Slabs Supported on Flexible Beams — Code Limitations......Page 474
11.3.4 The ‘Equivalent Frame’ Concept......Page 475
11.4.1 Code Procedures Based on the Equivalent Frame Concept......Page 479
11.4.2 Proportioning of Slab Thickness, Drop Panel and Column Head......Page 482
11.4.3 TRANSFER OF SHEAR AND MOMENTS TO COLUMNS IN BEAMLESS TWO-WAY SLABS......Page 486
11.5.1 Limitations......Page 488
11.5.3 Longitudinal Distribution of Total Design Moment......Page 489
11.5.4 Apportioning of Moments to Middle Strips, Column Strips and Beams......Page 492
11.5.6 Torsion in Edge Beam......Page 495
Effects of Pattern Loading on Slab Moments......Page 498
11.5.8 Beam Shears in Two-way Slab System with Flexible Beams......Page 499
11.6.1 Equivalent Frame for Analysis......Page 500
11.6.2 Slab-Beam Member......Page 502
Method of Analysis......Page 508
11.6.3 Loading Patterns......Page 510
11.6.4 Design Moments in Slab-Beam Members......Page 511
11.7 REINFORCEMENT DETAILS IN COLUMN-SUPPORTED TWO-WAY SLABS......Page 513
11.8.1 One-Way Shear or Beam Shear......Page 516
11.8.2 Two-Way Shear or Punching Shear......Page 518
SOLUTION......Page 523
SOLUTION......Page 533
REVIEW QUESTIONS......Page 549
REFERENCES......Page 552
12.1 INTRODUCTION......Page 554
12.2.1 Geometrical Configurations......Page 556
12.2.2 Structural Classification......Page 557
12.3 LOADS AND LOAD EFFECTS ON STAIR SLABS......Page 562
12.3.3 Distribution of Gravity Loads in Special Cases......Page 563
12.3.5 Load Effects in Waist Slabs......Page 564
12.3.6 Load Effects in Tread-Riser Stairs......Page 566
SOLUTION......Page 569
SOLUTION......Page 571
SOLUTION......Page 572
SOLUTION......Page 574
SOLUTION......Page 577
SOLUTION......Page 580
SOLUTION......Page 583
REVIEW QUESTIONS......Page 585
REFERENCES......Page 587
13.1.1 Classification of Columns Based on Type of Reinforcement......Page 588
13.1.2 Classification of Columns Based on Type of Loading......Page 589
13.1.3 Classification of Columns Based on Slenderness Ratios......Page 591
13.2.1 Definition of Effective Length......Page 592
13.2.2 Effective Length Ratios for Idealised Boundary Conditions......Page 593
13.2.3 Effective Length Ratios of Columns in Frames......Page 596
EXAMPLE 13.1......Page 598
SOLUTION......Page 599
SOLUTION......Page 602
13.3.1 Slenderness Limits......Page 604
13.3.3 Code Requirements on Reinforcement and Detailing......Page 605
13.4.1 Conditions of Axial Loading......Page 609
13.4.2 Behaviour Under Service Loads......Page 610
13.4.3 Behaviour Under Ultimate Loads......Page 611
13.4.4 Design Strength of Axially Loaded Short Columns......Page 613
SOLUTION......Page 614
SOLUTION......Page 615
13.5.1 Distribution of Strains at Ultimate Limit State......Page 617
13.5.2 Modes of Failure in Eccentric Compression......Page 619
13.5.3 Design Strength: Axial Load - Moment Interaction......Page 620
13.5.4 Analysis for Design Strength......Page 623
SOLUTION......Page 626
SOLUTION......Page 628
SOLUTION......Page 630
SOLUTION......Page 632
13.5.5 USE OF INTERACTION DIAGRAM AS AN ANALYSIS AID......Page 633
SOLUTION......Page 635
EXAMPLE 13.11......Page 638
SOLUTION......Page 639
13.5.6 Non-dimensional Interaction Diagrams as Design Aids......Page 641
SOLUTION......Page 646
SOLUTION......Page 647
SOLUTION......Page 648
13.6.1 Biaxial Eccentricities......Page 649
13.6.2 Interaction Surface for a Biaxially Loaded Column......Page 651
13.6.3 Code Procedure for Design of Biaxially Loaded Columns......Page 653
SOLUTION......Page 655
SOLUTION......Page 657
13.7.1 Behaviour of Slender Columns......Page 658
13.7.3 Code Procedures for Design of Slender Columns......Page 663
SOLUTION......Page 668
SOLUTION......Page 670
REVIEW QUESTIONS......Page 673
REFERENCES......Page 677
14.1 INTRODUCTION......Page 679
14.2 TYPES OF FOOTINGS......Page 680
14.2.2 Combined Footings......Page 682
14.3.1 Allowable Soil Pressure......Page 683
14.3.2 Distribution of Base Pressure......Page 684
14.3.3 Instability Problems: Overturning and Sliding......Page 689
14.4.1 Factored Soil Pressure at Ultimate Limit State......Page 690
14.4.2 General Design Considerations......Page 691
14.4.4 Design for Shear......Page 692
14.4.5 Design for Flexure......Page 694
14.4.6 Transfer of Forces at Column Base......Page 696
14.4.7 Plain Concrete Footings......Page 698
EXAMPLE 14.1: Design of a Plain Concrete Footing......Page 699
SOLUTION......Page 700
SOLUTION......Page 701
SOLUTION......Page 707
EXAMPLE 14.4: Masonry Wall Footing......Page 709
SOLUTION......Page 710
SOLUTION......Page 712
SOLUTION......Page 716
14.6.1 General......Page 718
14.6.4 Design Considerations in Two-Columns Footings......Page 719
SOLUTION......Page 724
14.7 TYPES OF RETAINING WALLS AND THEIR BEHAVIOUR......Page 729
14.8.1 Lateral Earth Pressures......Page 732
14.8.2 Effect of Surcharge on a Level Backfill......Page 734
14.8.3 Effect of Water in the Backfill......Page 735
14.8.4 Stability Requirements......Page 736
14.8.5 Soil Bearing Pressure Requirements......Page 737
14.9.1 Position of Stem on Base Slab for Economical Design......Page 738
14.9.2 Proportioning and Design of Elements of Cantilever Walls......Page 740
14.9.3 Proportioning and Design of Elements of a Counterfort Wall......Page 741
SOLUTION......Page 743
EXAMPLE 14.9......Page 745
SOLUTION......Page 746
EXAMPLE 14.10......Page 752
SOLUTION......Page 753
REVIEW QUESTIONS......Page 771
REFERENCES......Page 773
15.1 INTRODUCTION......Page 775
15.1.1 Serviceability Failures......Page 776
15.1.3 Structural Integrity......Page 777
15.2 DESIGN AND DETAILING PRACTICES......Page 778
15.2.1 Reinforcement Layout......Page 779
15.2.3 Construction Details at Connections and Special Situations......Page 780
15.2.4 Beam and Column Joints (Rigid Frame Joints)......Page 787
15.2.5 Construction Joints......Page 789
15.2.6 Bar Supports and Cover......Page 790
15.3 MATERIALS AND CONSTRUCTION PRACTICES......Page 791
15.4 SUMMARY......Page 793
REVIEW QUESTIONS......Page 794
REFERENCES......Page 795
16.1 INTRODUCTION......Page 797
16.2.1 Measures of Ductility......Page 799
16.2.2 Energy Dissipation by Ductile Behaviour......Page 801
16.2.3 Flexural Yielding in Frames and Walls......Page 803
16.3.2 Requirements of Stability and Stiffness......Page 804
16.3.3 Materials......Page 805
16.3.5 Flexural Members in Ductile Frames......Page 806
16.3.6 Columns and Frame Members Subject to Bending and Axial Load......Page 811
16.3.8 Shear Walls (Flexural Walls)......Page 815
16.3.9 Infill Frames......Page 817
16.3.10 Soft Storey......Page 818
REVIEW QUESTIONS......Page 819
REFERENCES......Page 820
17.1.1 Introduction......Page 822
17.1.2 General Concepts......Page 823
17.1.3 Stress-Strain Relationship for Diagonally Cracked Concrete......Page 825
(a) Assumptions and Equations – Case of Pure Shear......Page 826
(b) Shear with Bending Moment and Axial Force......Page 830
17.1.5 Simplified Design Procedure using Modified Compression Field Theory......Page 831
17.1.6 CSA Code Provisions for Shear Design by the Compression Field Theory......Page 835
17.1.7 Combined Shear and Torsion......Page 837
17.2 DESIGN USING STRUT-AND-TIE MODEL......Page 838
SOLUTION†......Page 844
17.3.1 Introduction......Page 849
17.3.2 Factors which influence Fire Resistance Ratings of RC Assemblies......Page 850
17.3.3 Code Requirements......Page 852
SOLUTION......Page 853
REVIEW QUESTIONS......Page 854
REFERENCES......Page 855