Experimental Investigation Of Performance Of Sprayed Fire Resistive Material On Steel Structures Under Post-Earthquake Fire

It is clear that steel structures are severely vulnerable to fire since the yield strength and the elastic modulus of the steel decease when the temperature increases, causing a reduction in the load-bearing capacity of the steel member. There are different methods for a steel element to reach required fire resistance rating. One of the most current methods in the world is the use of spray-applied mineral fire protective coatings. It is obvious that after a severe earthquake, the probability of the occurrence of the fire is high, e.g., because of the rupture of gas pipes. Unfortunately, there are not enough research pieces and reports on the performance of these coatings during an earthquake. However, we know that during a severe earthquake, the structure of the building will sustain significant deformations and it can cause the damage and delamination of the installed fire protective coating. Therefore, in this research, the post-earthquake fire performance of a mineral based spray-applied fire protection coating was studied. The type of this fire protection coating was cement based. Different application details of this mineral based spray-applied coating including coating thicknesses and reinforcing steel mesh details were investigated. First, four fire protected steel columns were subjected to cyclic lateral load tests. The type of the connection of these columns was a stiffened extended end-plate moment connection. This connection type was used for special steel moment frames. The thickness of the fire protection coating for steel specimens was determined for fire resistance rating of three hours. Then, these columns together with two reference columns were subjected to fire resistance tests to make a comparison between results. By using the qualitative and quantitative results of these tests, the type and amount of seismic damage of fire protection coating were determined in earthquakes with two different intensities. Also, it became clear that reinforcing the fire protective coating with a steel mesh in the region of formation of seismic plastic hinge in a steel element could reduce the seismic damage of the coating sufficiently.