ACI 318-19(22) is the Building Code Requirements for Structural Concrete and Commentary, published by the American Concrete Institute. It provides minimum requirements for the design, materials, and detailing of structural concrete used in buildings and other structures. The 2022 version includes errata and updates to the 2019 edition.

The primary purposes of this standard are to:

• Ensure public health and safety in concrete structures
• Provide guidelines for the design and construction of structural concrete
• Establish minimum requirements for concrete strength, durability, and performance
• Facilitate compliance with building codes and regulations

This standard is intended for use by:

• Structural engineers and designers
• Architects
• Contractors and construction professionals
• Building officials and inspectors
• Concrete manufacturers and suppliers
• Researchers and educators in the field of structural concrete

The standard includes:

• Design requirements for various structural elements (beams, columns, slabs, etc.)
• Material specifications and quality control measures
• Construction practices and inspection requirements
• Provisions for special structures and seismic design
• Commentary providing background and explanations for code provisions

While ACI 318 itself is not law, it is often adopted by reference in building codes and regulations. When incorporated into local building codes, compliance becomes mandatory for construction projects in those jurisdictions.

ACI 318 is typically updated every six years. The current version, ACI 318-19, was published in 2019. The 2022 reapproval (ACI 318-19(22)) includes errata and reference updates but no technical changes.

The commentary provides:

• Explanations of the code requirements
• Background information on the development of provisions
• Guidance on applying the code in practice
• References to research and other relevant standards

ACI 318-19(22) includes comprehensive provisions for earthquake-resistant structures, including:

• Design requirements for special moment frames and structural walls
• Detailing provisions for ductile behavior
• New methods for nonlinear analysis in seismic design

The standard covers a wide range of topics, including:

Structural systems design
Durability requirements
Flexural and axial load design
Shear and torsion design
Anchoring to concrete
Reinforcement detailing
Precast and prestressed concrete
Concrete materials and quality

ACI 318-19(22) is designed to be compatible with other important standards, such as:

• ASCE 7 for minimum design loads
• International Building Code (IBC)
• Other ACI standards for specific concrete applications

It serves as a primary reference for concrete design in many building codes worldwide.

ACI 318-19 introduces several significant updates:

• Allowance for higher strength reinforcement (up to Grade 100 for some applications)
• New seismic design provisions for structural walls
• Simplified shear design equations for beams and slabs
• Updated development length requirements for reinforcement
• New provisions for deep foundations
• Expanded durability requirements
• Introduction of screw anchors and shear lugs
• Updates to post-tensioning and precast concrete provisions

ACI 318-19 now allows:

• Grade 80 reinforcement for some special seismic systems
• Grades 60, 80, or 100 for shear walls
• Grades 60 or 80 for special moment frames
• Grade 40 rebar is no longer allowed in seismic applications

New requirements include:

• All crossties for special boundary elements must have 135-degree hooks at both ends
• Restrictions on vertical reinforcement lap splice locations near plastic hinge zones
• New provisions to check detailing adequacy for earthquake displacement demands
• Amplification of wall design shears based on flexural overstrength and higher dynamic response modes

ACI 318-19 introduces:

• Simplified equations for one-way and two-way (punching) shear
• Consideration of size effect in shear design
• Ability to account for reinforcement ratio in shear strength calculations

Updates include:

• Modified straight bar development length provisions
• New calculation methods for hooked and headed bar development lengths
• Introduction of a reinforcement growth factor based on bar strength

The standard now includes:

• Provisions for allowable axial capacities consistent with IBC allowable stress provisions
• Strength design requirements aligned with ACI 543R-12
• Options for using either traditional allowable strengths or strength design method

ACI 318-19 includes:

• Additional requirements for sulfate exposure classes
• New provisions for concrete exposed to water
• Requirements for preventing alkali-silica reaction (ASR)

Changes include:

• Clarifications on construction requirements for prestress loss
• Introduction of a new reference document for determining prestress losses
• Updates to deformed and bonded reinforcement spacing limitations
• Clarifications on anchorage zone reinforcement requirements

Updates include:

• Removal of "bottle-shaped struts" terminology
• Inclusion of minimum reinforcing requirements in STM
• Improvements for curved-bar nodes and knee joints
• Addition of seismic design provisions related to STM

The load testing provisions have been updated to become more consistent with other ACI standards.

ACI 318-19 now includes commentary language allowing its use for analysis, repair, and rehabilitation of existing structures, recognizing ACI 562 (Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures).

Changes include:

Addition of commentary language on vibration analysis
Adjustments to calculations of effective moment of inertia (Ie) for nonprestressed reinforced concrete

The standard now adopts the precast concrete diaphragm design procedure from ACI 550.5. What changes have been made regarding shrinkage and temperature reinforcement? The requirements for shrinkage and temperature reinforcement have been simplified in ACI 318-19.