Structural fire endurance experiments were conducted on full-scale cellular glass fiber-reinforced (GFRP) columns under axial compression and subjected to ISO834 fire exposure from one side. Unprotected columns can resist fire for more than 30 min, which is sufficient for occupants to be evacuated from smaller buildings. The closed cellular cross-section prevented the rapid heating of the webs, which could therefore continue stabilizing the face sheet on the cold side against buckling. Water cooling was proven to offer an effective active fire-protection system. The structural function of the column could be maintained for two hours. Previously developed models were capable of accurately predicting the time-dependent temperature responses, modulus degradation, and time to failure. DOI: 10.1061/(ASCE)CC.1943-5614.0000160. (C) 2011 American Society of Civil Engineers.