Evaluate Polypropylene Fiber Effect on Concrete Segments of Tunnel under Fire

In today`s world urban railway is one of the important transportation systems that should be examined against various environmental phenomena including fire condition to service permanent citizens. Usually construction of concrete segments of the tunnel simultaneous to used high strength concrete (HSC) that have bad reaction under fire in spite of good seismic reaction. When a fire occurs in tunnel surrounding, some interaction occurred in concrete segments of the tunnel that can reduce the thickness and decrease the safety of these segments. Most of the researches in applying heat effect on concrete segments of the tunnel are experimental and under this situation and analytical or numerical researches in this issue are low. This paper presents an analytical model using ABAQUS software based on the finite element for evaluating concrete segments of tunnel behaviour under fire condition. To ensure the safety of results, some fire curves are applied and effect of Polypropylene fiber in the concrete mix is evaluated. Results show that adding minimum 0.9 Kg per cubic meter of concrete mix in concrete segments of tunnel causing loss of spalling and improve fire behavior interaction.