Effect of High Temperature on CFRP Retroffitted Columns, Protected with Different Coatings

Abstract

This paper presents an experimental investigation on the effect of indirect fire on axially loaded CFRP retrofitted columns. Tests were performed on 28 half scale CFRP retrofitted columns, coated with proposed heat insulating covers (two specimens were cast for each type). Twelve materials - known for their low coefficients of thermal conductivities- were used in the mixes of these protective covers on CFRP. Commercially available fire protective material was subjected to the same tests also. All protected columns were exposed to elevated temperature tests following ASTM (E119-95a) fire test curve 900°C for half an hour, while an axial load is applied to simulate working load conditions.

Thermal distribution results along columns cross sections- for different insulating covers- at different stages of the fire test- were compared to evaluate the efficiency of the proposed heat protecting mixes.

Post fire tests, all columns were loaded up to failure. Hence, the reduction in their load capacity due to fire exposure is calculated.

Throughout these comparisons, it is concluded that the most of the suggested insulating mixes acted efficiently to protect CFRP strengthened sections during fire. Temperature was significantly reduced at CFRP level -below the protective covers. It ranged between 100-120°C, for most of the mixes. Thus, enhancing significantly the fire resistance for CFRP retrofitted columns. Reduction in failure load capacity -due to fire exposure- was limited to 10-20% for most of the protected specimens. Even for the insulating mixes that resulted in lowest - post fire- residual strength, CFRP layer was highly damaged, but the reinforced concrete section was slightly affected, which still makes the damage repairable.

Citation

Elkady, H. (2010), "Effect of High Temperature on CFRP Retroffitted Columns, Protected with Different Coatings", Journal of Structural Fire Engineering, Vol. 1 No. 2, pp. 89-100. https://doi.org/10.1260/2040-2317.1.2.89