Approaches for the assessment and repair of concrete elements exposed to fire

An adequate assessment of the residual strength of concrete structures exposed to fire is necessary for executing an appropriate repair. This strength can be determined indirectly by assessing the temperature history inside the concrete. Different techniques, such as colorimetry and water immersion are outlined in this paper. In the (L)ab colour space, an elliptical path is found as a function of the temperature. However, the strength is influenced by the test setup and storage conditions after fire. Storing the concrrete in ambient air may introduce an additional strength loss up to 20 percent. Once the temperature distribution in the concrete is known, the residual capacity of a concrete element can be calculated. The use of the finite element program TNO DIANA in combination with simple calculations is illustrated for a concrete girder exposed to a real fire and afterwards repaired with shotcrete.An adequate assessment of the residual strength of concrete structures exposed to fire is necessary for executing an appropriate repair. This strength can be determined indirectly by assessing the temperature history inside the concrete. Different techniques, such as colorimetry and water immersion are outlined in this paper. In the (L)ab colour space, an elliptical path is found as a function of the temperature. However, the strength is influenced by the test setup and storage conditions after fire. Storing the concrrete in ambient air may introduce an additional strength loss up to 20 percent. Once the temperature distribution in the concrete is known, the residual capacity of a concrete element can be calculated. The use of the finite element program TNO DIANA in combination with simple calculations is illustrated for a concrete girder exposed to a real fire and afterwards repaired with shotcrete.C