Steel, concrete, timber, and composites at elevated temperature — Ch. 37 orientation.

Scope

CivilTech notes on structural fire behaviour and design. Not a substitute for project codes, approvals, or peer review.

Regulatory context. South African projects follow National Building Regulations, SANS 10400, and cited material standards; use this material as orientation only.

Using this page

  1. Context — Cross-check these notes with your project fire strategy and the code edition on the job.
  2. Tools — The Fire Engineering page has ISO 834 and steel-retention calculators for quick checks.
  3. Approval — Fire resistance and structural fire design remain subject to the local authority and appointed engineers.

Fire engineering — Material behavior

Section 4 — Strength, stiffness, and deformation capacity change with temperature; models are code- or literature-based.

Steel

Yield strength and stiffness reduce with temperature; retention factors are used in simplified checks. Connections and local buckling remain critical.

Concrete

Compressive strength and elastic modulus degrade; spalling can expose reinforcement and change section capacity. Moisture and heating rate matter.

Timber and other materials

Timber charring reduces effective section; protective linings alter exposure. Composites and masonry each have their own degradation rules in specialist guidance.

Diagram sources

This page has no diagram assets. Text is CivilTech orientation on material behaviour at temperature—use approved retention models and standards for design.