ISO 22111:2019

Overview - ISO 22111:2019 (Bases for design of structures)

ISO 22111:2019 establishes general requirements for structural design using a semi‑probabilistic limit states approach to achieve consistent structural reliability. It defines the framework for deriving design values and verification procedures where sufficient knowledge and experience of design and construction exist. The standard is aligned with the general principles in ISO 2394 and is intended to help standards bodies, code writers and designers set target levels of reliability and quantitative design parameters for common structural types.

Key topics and technical requirements

• Semi‑probabilistic limit states approach - verification methods proven to deliver consistent reliability.
• Scope limitations - applies only where adequate information exists on design practice, materials and uncertainties; more complex or less understood cases are addressed by ISO 2394.
• Definitions, symbols and terminology - standardized terms for actions, resistances, limit states and reliability classes.
• Fundamental performance requirements - design situations, limit states (ultimate and serviceability), and verification principles.
• Actions and action combinations - classification and design values for permanent, variable and accidental actions; rules for combining effects.
• Resistance - treatment of material properties, geometrical data, characteristic and design values of resistance.
• Analysis and testing - recommended analysis procedures and test considerations for demonstrating performance.
• Demonstrating conformance - procedures to verify ultimate limit states, serviceability, robustness (including collapse scenarios) and durability.
• Guidance annexes - informative annexes on adoption, formats for presenting design values, target reliability practice and an illustrative design procedure.

Applications and users

Who uses ISO 22111:2019:

• Standards organizations and code committees - to set national or regional target reliability levels and design parameters.
• Structural engineers and designers - for design verification using semi‑probabilistic limit state methods.
• Regulators and authorities - to express mandatory requirements in an internationally consistent format.
• Academics and researchers - for teaching and development of harmonized reliability-based design methods.
• Testing laboratories - for defining test-based resistance and validation procedures.

Practical uses:

• Harmonizing building, bridge and industrial-structure design rules.
• Establishing design value formats for actions and resistances.
• Integrating robustness and durability checks into design verification.
• Facilitating international adoption of consistent structural reliability practices.

Related standards

• ISO 2394 - General principles for structural reliability (reference standard that complements ISO 22111:2019).
• ISO 22111 is intended to be used together with material- and action-specific standards referenced within it when deriving design inputs.

Keywords: ISO 22111:2019, bases for design of structures, structural reliability, semi-probabilistic, limit states, design verification, ISO 2394.