ACI 318-14 Building Code Requirements for Structural Concrete and Commentary

The “Building Code Requirements for Structural Concrete” (“Code”) provides minimum requirements for the materials, design, and detailing of structural concrete buildings and, where applicable, nonbuilding structures. This Code addresses structural systems, members, and connections, including cast-in-place, precast, plain, nonprestressed, prestressed, and composite construction. Among the subjects covered are: design and construction for strength, serviceability, and durability; load combinations, load factors, and strength reduction factors; structural analysis methods; deflection limits; mechanical and adhesive anchoring to concrete; development and splicing of reinforcement; construction document information; field inspection and testing; and methods to evaluate the strength of existing structures. “Building Code Requirements for Concrete Thin Shells” (ACI 318.2) is adopted by reference in this Code. CHAPTER 1—GENERAL 11 1.1—Scope of ACI 318 11 1.2—General 11 1.3—Purpose 12 1.4—Applicability 12 1.5—Interpretation 13 1.6—Building official 14 1.7—Licensed design professional 15 1.8—Construction documents and design records 15 1.9—Testing and inspection 15 1.10—Approval of special systems of design, construction, or alternative construction materials 15 CHAPTER 2—NOTATION AND TERMINOLOGY 17 2.1—Scope 17 2.2—Notation 17 2.3—Terminology 32 CHAPTER 3—REFERENCED STANDARDS 47 3.1—Scope 47 3.2—Referenced standards 47 CHAPTER 4—STRUCTURAL SYSTEM REQUIREMENTS 51 4.1—Scope 51 4.2—Materials 51 4.3—Design loads 51 4.4—Structural system and load paths 51 4.5—Structural analysis 54 4.6—Strength 54 4.7—Serviceability 55 4.8—Durability 55 4.9—Sustainability 55 4.10—Structural integrity 56 4.11—Fire resistance 56 4.12—Requirements for specific types of construction 56 4.13—Construction and inspection 58 4.14—Strength evaluation of existing structures 58 CHAPTER 5—LOADS 59 5.1—Scope 59 5.2—General 59 5.3—Load factors and combinations 60 CHAPTER 6—STRUCTURAL ANALYSIS 65 6.1—Scope 65 6.2—General 65 6.3—Modeling assumptions 70 6.4—Arrangement of live load 71 6.5—Simplified method of analysis for nonprestressed continuous beams and one-way slabs 72 6.6—First-order analysis 73 6.7—Elastic second-order analysis 81 6.8—Inelastic second-order analysis 83 6.9—Acceptability of finite element analysis 83 CHAPTER 7—ONE-WAY SLABS 85 7.1—Scope 85 7.2—General 85 7.3—Design limits 85 7.4—Required strength 87 7.5—Design strength 87 7.6—Reinforcement limits 88 7.7—Reinforcement detailing 90 CHAPTER 8—TWO-WAY SLABS 95 8.1—Scope 95 8.2—General 95 8.3—Design limits 96 8.4—Required strength 99 8.5—Design strength 104 8.6—Reinforcement limits 105 8.7—Reinforcement detailing 108 8.8—Nonprestressed two-way joist systems 119 8.9—Lift-slab construction 120 8.10—Direct design method 120 8.11—Equivalent frame method 126 CHAPTER 9—BEAMS 131 9.1—Scope 131 9.2—General 131 9.3—Design limits 132 9.4—Required strength 134 9.5—Design strength 136 9.6—Reinforcement limits 138 9.7—Reinforcement detailing 142 9.8—Nonprestressed one-way joist systems 151 9.9—Deep beams 153 CHAPTER 10—COLUMNS 155 10.1—Scope 155 10.2—General 155 10.3—Design limits 155 10.4—Required strength 156 10.5—Design strength 157 10.6—Reinforcement limits 158 10.7—Reinforcement detailing 159 CHAPTER 11—WALLS 165 11.1—Scope 165 11.2—General 165 11.3—Design limits 166 11.4—Required strength 166 11.5—Design strength 167 11.6—Reinforcement limits 170 11.7—Reinforcement detailing 171 11.8—Alternative method for out-of-plane slender wall analysis 173 CHAPTER 12—DIAPHRAGMS 175 12.1—Scope 175 12.2—General 175 12.3—Design limits 177 12.4—Required strength 177 12.5—Design strength 180 12.6—Reinforcement limits 187 12.7—Reinforcement detailing 187 CHAPTER 13—FOUNDATIONS 189 13.1—Scope 189 13.2—General 191 13.3—Shallow foundations 194 13.4—Deep foundations 195 CHAPTER 14—PLAIN CONCRETE 197 14.1—Scope 197 14.2—General 198 14.3—Design limits 198 14.4—Required strength 200 14.5—Design strength 201 14.6—Reinforcement detailing 204 CHAPTER 15—BEAM-COLUMN AND SLAB-COLUMN JOINTS 205 15.1—Scope 205 15.2—General 205 15.3—Transfer of column axial force through the floor system 205 15.4—Detailing of joints 206 CHAPTER 16—CONNECTIONS BETWEEN MEMBERS 207 16.1—Scope 207 16.2—Connections of precast members 207 16.3—Connections to foundations 211 16.4—Horizontal shear transfer in composite concrete flexural members 214 16.5—Brackets and corbels 216 CHAPTER 17—ANCHORING TO CONCRETE 223 17.1—Scope 223 17.2—General 224 17.3—General requirements for strength of anchors 230 17.4—Design requirements for tensile loading 236 17.5—Design requirements for shear loading 249 17.6—Interaction of tensile and shear forces 260 17.7—Required edge distances, spacings, and thicknesses to preclude splitting failure 260 17.8—Installation and inspection of anchors 262 CHAPTER 18—EARTHQUAKE-RESISTANT STRUCTURES 265 18.1—Scope 265 18.2—General 265 18.3—Ordinary moment frames 271 18.4—Intermediate moment frames 271 18.5—Intermediate precast structural walls 276 18.6—Beams of special moment frames 277 18.7—Columns of special moment frames 282 18.8—Joints of special moment frames 287 18.9—Special moment frames constructed using precast concrete 291 18.10—Special structural walls 294 18.11—Special structural walls constructed using precast concrete 306 18.12—Diaphragms and trusses 306 18.13—Foundations 312 18.14—Members not designated as part of the seismic-force-resisting system 314 CHAPTER 19—CONCRETE: DESIGN AND DURABILITY REQUIREMENTS 317 19.1—Scope 317 19.2—Concrete design properties 317 19.3—Concrete durability requirements 318 19.4—Grout durability requirements 326 CHAPTER 20—STEEL REINFORCEMENT PROPERTIES, DURABILITY, AND EMBEDMENTS 327 20.1—Scope 327 20.2—Nonprestressed bars and wires 327 20.3—Prestressing strands, wires, and bars 332 20.4—Structural steel, pipe, and tubing for composite columns 335 20.5—Headed shear stud reinforcement 336 20.6—Provisions for durability of steel reinforcement 336 20.7—Embedments 341 CHAPTER 21—STRENGTH REDUCTION FACTORS 343 21.1—Scope 343 21.2—Strength reduction factors for structural concrete members and connections 343 CHAPTER 22—SECTIONAL STRENGTH 349 22.1—Scope 349 22.2—Design assumptions for moment and axial strength 349 22.3—Flexural strength 351 22.4—Axial strength or combined flexural and axial strength 352 22.5—One-way shear strength 353 22.6—Two-way shear strength 362 22.7—Torsional strength 373 22.8—Bearing 380 22.9—Shear friction 382 CHAPTER 23—STRUT-AND-TIE MODELS 387 23.1—Scope 387 23.2—General 388 23.3—Design strength 394 23.4—Strength of struts 394 23.5—Reinforcement crossing bottle-shaped struts 396 23.6—Strut reinforcement detailing 397 23.7—Strength of ties 397 23.8—Tie reinforcement detailing 398 23.9—Strength of nodal zones 399 CHAPTER 24—SERVICEABILITY REQUIREMENTS 401 24.1—Scope 401 24.2—Deflections due to service-level gravity loads 401 24.3—Distribution of flexural reinforcement in one-way slabs and beams 405 24.4—Shrinkage and temperature reinforcement 407 24.5—Permissible stresses in prestressed concrete flexural members 409 CHAPTER 25—REINFORCEMENT DETAILS 413 25.1—Scope 413 25.2—Minimum spacing of reinforcement 413 25.3—Standard hooks, seismic hooks, crossties, and minimum inside bend diameters 414 25.4—Development of reinforcement 416 25.5—Splices 430 25.6—Bundled reinforcement 435 25.7—Transverse reinforcement 436 25.8—Post-tensioning anchorages and couplers 445 25.9—Anchorage zones for post-tensioned tendons 445 CHAPTER 26—CONSTRUCTION DOCUMENTS AND INSPECTION 455 26.1—Scope 455 26.2—Design criteria 457 26.3—Member information 457 26.4—Concrete materials and mixture requirements 457 26.5—Concrete production and construction 464 26.6—Reinforcement materials and construction requirements 470 26.7—Anchoring to concrete 474 26.8—Embedments 475 26.9—Additional requirements for precast concrete 475 26.10—Additional requirements for prestressed concrete 476 26.11—Formwork 478 26.12—Concrete evaluation and acceptance 480 26.13—Inspection 485 CHAPTER 27—STRENGTH EVALUATION OF EXISTING STRUCTURES 489 27.1—Scope 489 27.2—General 489 27.3—Analytical strength evaluation 490 27.4—Strength evaluation by load test 491 27.5—Reduced load rating 494 COMMENTARY REFERENCES 495 American Association of State Highway and TransportationOfficials (AASHTO) 495 American Concrete Institute (ACI) 495 American Institute of Steel Construction (AISC) 496 American Iron and Steel Institute (AISI) 496 American Society of Civil Engineers (ASCE) 496 American Society of Mechanical Engineers (ASME) 496 American Welding Society (AWS) 496 ASTM International 496 Federal Emergency Management Agency (FEMA) 497 International Code Council (ICC) 497 National Fire Protection Association (NFPA) 497 Portland Cement Association (PCA) 497 Precast/Prestressed Concrete Institute (PCI) 497 Post-Tensioning Institute (PTI) 497 Steel Deck Institute (SDI) 497 Authored documents 497 APPENDIX A—STEEL REINFORCEMENT INFORMATION 509 ASTM STANDARD REINFORCING BARS 509 ASTM STANDARD PRESTRESSING STRANDS,WIRES, AND BARS 509 WRI STANDARD WIRE REINFORCEMENT 510 APPENDIX B 511 INDEX 519 admixtures;,aggregates;,anchorage,(structural);,beam-column,frame;,beams,(supports);,building,codes;,cements;,cold,weather,construction;,columns,(supports);,combined,stress;,composite,construction,(concrete,and,steel);,composite,construction,(concrete,to,concrete);,compressive,strength;,concrete,construction;,concrete,slabs;,concretes;,construction,joints;,continuity,(structural);,contract,documents;,contraction,joints;,cover;,curing;,deep,beams;,deflections;,earthquake-resistant,structures;,embedded,service,ducts;,flexural,strength;,floors;,folded,plates;,footings;,formwork,(construction);,frames;,hot,weather,construction;,inspection;,isolation,joints;,joints,(junctions);,joists;,lightweight,concretes;,load,tests,(structural);,loads,(forces);,materials;,mixing;,mixture,proportioning;,modulus,of,elasticity;,moments;,pipe,columns;,pipes,(tubing);,placing;,plain,concrete;,precast,concrete;,prestressed,concrete;,prestressing,steels;,quality,control;,reinforced,concrete;,reinforcing,steels;,roofs;,serviceability;,shear,strength;,shear,walls;,shells,(structural,forms);,spans;,splicing;,strength;,strength,analysis;,stresses;,structural,analysis;,structural,concrete;,structural,design;,structural,integrity;,T-beams;,torsion;,walls;,water;,welded,wire,reinforcement The "Building Code Requirements for Structural Concrete" ("Code") provides minimum requirements for the materials, design, and detailing of structural concrete buildings and, where applicable, nonbuilding structures. This Code addresses structural systems, members, and connections, including cast-in-place, precast, plain, nonprestressed, prestressed, and composite construction. Among the subjects covered are: design and construction for strength, serviceability, and durability; load combinations, load factors, and strength reduction factors; structural analysis methods; deflection limits; mechanical and adhesive anchoring to concrete; development and splicing of reinforcement; construction document information; field inspection and testing; and methods to evaluate the strength of existing structures. "Building Code Requirements for Concrete Thin Shells" (ACI 318.2) is adopted by reference in this Code. The Code user will find that ACI 318-14 has been substantially reorganized and reformatted from previous editions. The principal objectives of this reorganization are to present all design and detailing requirements for structural systems or for individual members in chapters devoted to those individual subjects, and to arrange the chapters in a manner that generally follows the process and chronology of design and construction. Information and procedures that are common to the design of members are located in utility chapters ... The quality and testing of materials used in construction are covered by reference to the appropriate ASTM standard specifications. Welding of reinforcement is covered by reference to the appropriate American Welding Society (AWS) standard. Uses of the Code include adoption by reference in a general building code, and earlier editions have been widely used in this manner. The Code is written in a format that allows such reference without change to its language. Therefore, background details or suggestions for carrying out the requirements or intent of the Code provisions cannot be included within the Code itself. The Commentary is provided for this purpose. Some of the considerations of the committee in developing the Code are discussed within the Commentary, with emphasis given to the explanation of new or revised provisions. Much of the research data referenced in preparing the Code is cited for the user desiring to study individual questions in greater detail. Other documents that provide suggestions for carrying out the requirements of the Code are also cited. Technical changes from ACI 318-11 to ACI 318-14 are outlined in the May 2014 issue of Concrete International. Transition keys showing how the code was reorganized are provided on the ACI website on the 318 Resource Page under Topics in Concrete 318-14 Epub available soon. The "Building Code Requirements for Structural Concrete" ("Code") provides minimum requirements for the materials, design, and detailing of structural concrete buildings and, where applicable, nonbuilding structures. This Code addresses structural systems, members, and connections, including cast-in-place, precast, plain, nonprestressed, prestressed, and composite construction. Among the subjects covered are: design and construction for strength, serviceability, and durability; load combinations, load factors, and strength reduction factors; structural analysis methods; deflection limits; mechanical and adhesive anchoring to concrete; development and splicing of reinforcement; construction document information; field inspection and testing; and methods to evaluate the strength of existing structures. "Building Code Requirements for Concrete Thin Shells" (ACI 318.2) is adopted by reference in this Code.The Code user will find that ACI 318-14 has been substantially reorganized and reformatted from previous editions. The principal objectives of this reorganization are to present all design and detailing requirements for structural systems or for individual members in chapters devoted to those individual subjects, and to arrange the chapters in a manner that generally follows the process and chronology of design and construction. Information and procedures that are common to the design of members are located in utility chapters