Thermal actions on structures: convection, radiation, conduction, and boundary conditions — 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 — Thermal actions

Section 3 — Heat transfer from the fire environment to structural surfaces drives temperature rise in members.

Mechanisms

Convection links gas temperature and flow to surface heat flux. Radiation dominates in many post-flashover conditions. Conduction governs heat penetration into solids once boundary heat flux is known.

Boundary conditions

Engineers specify emissivity, view factors, and exposed area for members; protected members add insulation layers with effective thermal properties.

Link to structural analysis

Thermal analysis yields time–temperature fields in cross-sections; these feed material models and strength checks at elevated temperature.

Diagram sources

This page has no diagram assets. Text is CivilTech orientation on heat transfer and boundaries—verify methods and inputs against project codes and fire engineering reports.