Structural Steel

Modern buildings are becoming more complex resulting in continued challenges in building and ensuring occupier safety. Significant advances in the knowledge of steel behaviour in fire have been made in recent years, however issues around fire and steel frame fire protection remain critical to the future safety of the building fabric.

Promat’s recently published White Paper ‘Introduction to Making the Right Choice’ will assist architects and specifier professionals in making informed fire protection decisions. The paper covers:

• Introduction to steel protection
• The challenges facing the specification community
• Fire protection options for steel structures
• Key considerations for specification choice: cost, build programme, weather, curing time, repair and maintenance
• Requirements for castellated/cellular beams
• Conducting the correct thickness checks
• Summary
• Fire protection design guidance overview

The white paper is now available for free download from www.promat.co.uk/steel-fire-protection 

Also available through the Document Tab on this page or Document Library once Website Account Registration is complete)

Building Regulations (Document B) require certain elements of structures to have fire resistance for a specified minimum period of time. The amount of fire protection required to achieve this depends on the following:

• Shape and size of the steel section
• Perimeter of the steel section exposed to fire
• Duration of fire resistance specified
• Type of protection used
• Limiting temperature of steel section
• Test standard BS or EN requirement
  

A/V Section Factor: the degree of fire protection depends on the A/V section factor for the steel section. The A/V factor is a function of the area of the steel exposed to the fire and the volume of the steel section. The higher the A/V, the faster the steel section heats up, and so the greater the thickness of fire protection material required. The section factor and limiting temperature are then used to determine the thickness of protection required.

Tests in accordance with BS 476: Part 21: 1987 have been performed on loaded beams and columns clad with Promat fire protection materials. Steel temperatures are monitored with thermocouples to assess the performance of the fire protection, since steel fully stressed in accordance with BS 449: Part 2: 1969 or BS 5950: Part 1: 2000 begins to lose its design margin of safety at temperatures around 550°C.

A range of unloaded sections has also been tested to obtain data for calculating exactly how much protection is needed for the most common steel sections and for providing fire resistance for different time periods.

These and other tests have also demonstrated the ability of the fire protection to remain in place, commonly termed as the ‘stickability’ of the material, for the maximum duration for which protection may be required. The availability of thin boards and the low weight of Promat boards plus the possibility of pre-fabrication ensure maximum cost-efficiency.