Effect of Damaged Fireproofing on the Behavior of Structural Steel Members

Fireproofing is a passive fire protection applied structural steel members to reduce heat transfer to the structural steel members so that the rate of temperature rise of the load bearing components is reduced and a structural failure is delayed or does not occur. In other words, fireproofing helps the structural elements to properly function during a fire event for a certain period of time, also know as fire resistant rating. Different types of fireproofing applied to structural steel members such as concrete encasement, spray applied fire resistive materials (SFRM), intumescent coating, and gypsum board. This study focuses on the concrete encasement, which is widely used in oil and gas refineries and petrochemical facilities. Damage to fireproofing may occur due to accidental damage, long-term weathering, vibration, and improper application during construction. It is very important to understand how effective damaged fireproofing is since it is a phenomenon that occurs more often in practice. Damaged fireproofing or loss of fireproofing affects the strength and stiffness of structural steel members dramatically and raises the question of how effective is the remaining fireproofing during a fire event. Different types of damage such as extent of damaged fireproofing along the length of the members, partial loss of fireproofing across its thickness, and location of the damage. Failure modes, deflection, member capacity, and local instabilities were investigated at elevated temperature and compared with same members that are fully protected and without damage.