Residual strength of high strength concentric column-SFRC flat plate exposed to high temperatures

- Punching shear of twenty fiber-reinforced interior flat plate specimens was tested.
- High-strength steel-fiber reinforced concrete was used to cast the specimens.
- The residual punching shear strength was investigated after high temperature exposure.
- Other mechanical properties were also investigated after high temperature exposure.
- The incorporation of steel fibers enhanced the behavior of the tested flat plates.

It became well known that steel fibers could significantly improve the mechanical properties of concrete and the ductility of flat plat-column assembly at ambient conditions. The investigation of the contribution of the steel fiber and the high strength concrete under high temperature conditions on the structural behavior of flat plates is still in need. This research presents experimental results of sixteen steel fiber reinforced slabs exposed to four levels of temperature reaching 550 °C, in addition to four control slab specimens. The residual mechanical properties, ultimate slab strength, and deformations were investigated. Relations between the concrete tensile and compressive strengths after exposing to high temperatures were introduced. For all temperature levels and steel fiber contents, the strength of most of the slabs was improved compared to the corresponding strength at room temperature. The highest percentage improvement was recorded for specimens exposed to 150 °C and reinforced with 1% of steel fiber. The strengths of the slabs with 1% and 1.25% of steel fiber and exposed to 550 °C were almost the same as their strengths at ambient conditions, however, slabs with 0.75% showed 13% increase.