An approach for evaluating the residual strength of fire exposed bridge girders

作者：Aziz Esam; Kodur Venkatesh^*

来源：Journal of Constructional Steel Research, 2013, 88: 34-42.

DOI：10.1016/j.jcsr.2013.04.007

• Bridge fires
• Residual strength
• Steel girders
• Finite element analysis
• Fire resistance

This paper presents an approach for evaluating residual strength of fire exposed steel bridge girders. The approach involves three stages of analysis that is to be carried out at ambient conditions, during exposure to fire, and after cooling of the fire exposed bridge girder. In the first stage, load carrying capacity of the girder is evaluated at room temperature. In the second stage of analysis, thermal and structural response of the bridge girder is traced under specified fire exposure and loading conditions. In the third stage (after the bridge girder has cooled down), residual capacity of the girder is evaluated by incrementing load on the girder till failure occurs. The proposed approach is applied to carry out a set of numerical studies on a typical steel girder using finite element computer program ANSYS. Results from numerical studies indicate that the maximum fire temperature (and associated temperature in steel) is the most critical factor that influences residual strength of a fire exposed bridge girder. A girder exposed to typical %26quot;external%26quot; fire conditions, with maximum fire temperatures reaching to 600-700 degrees C, retains about 70 to 80% of its strength on cooling. On the other hand, a steel bridge girder exposed to hydrocarbon fire, with a maximum temperature of about 1100 degrees C, looses most of its strength during heating phase of the fire and experiences failure.

• 出版日期2013-9