Shear transfer across a crack in high-strength concrete after elevated temperatures

• High temperature tests on two grades of HSC specimens were carried out.
• Push-off test on HSC specimens after elevated temperatures was firstly performed.
• Effect of elevated temperatures on shear transfer behavior of HSC was revealed.
• Relationships between HSC shear strength and exposed temperature were proposed.

This paper experimentally investigated the shear transfer behavior of high-strength concrete (HSC) across a crack after elevated temperatures. The compressive strength of concrete and the experienced temperature were the two main parameters in this study. Twenty-two uncracked push-off specimens were casted and heated in an electrical furnace. Push-off tests were then conducted to study the shear strength and the crack formulation and deformation of the concrete after elevated temperatures. The elevated temperature test results indicate that the heating process of HSC is related to the furnace chamber temperature, the thermal convection and the thermal radiation. The heating process can be divided into 3 stages based on the heating time. Except for an exposed temperature of 200 °C, the ultimate shear strength of HSC reduces and the corresponding crack deformation (crack slip and crack width) increases with the increase of the temperature. The shear brittleness of HSC decreases as the exposed temperature increases. The higher the strength of concrete is, the more brittle the shear transfer characteristics becomes. Finally, the equation for estimating the residual shear strength of HSC after elevated temperatures are proposed based on the statistical analysis of the test data.