Dynamic Increase Factor of Concrete Subjected to Compression and Tension by using Split Hopkinson Pressure Bar Setup: Overview

The dynamic increase factor (DIF) for the dynamic compressive and tensile strength of concrete-like brittle materials subjected to impact and blast loading has been a broad subject of extensive investigation and debate for many years. The necessity of studying the dynamic behaviour of concrete-like brittle material is increasing daily for the analysis and design of building structures for safety and security purposes. In this context, this paper reviews and summarizes the dynamic increase factor obtained from experimental and numerical studies under compression and tension for their resistance under a high loading rate. Numerous researchers have conducted Split Hopkinson Pressure Bar (SHPB) experiments on concrete, mortar, and composite materials. They have proposed several empirical relationships between the strain rate and Dynamic Increase Factor (DIF). These DIF values, suitable for both compression and tension, have gained extensive acceptance in authoritative design guidelines and model codes for numerical simulation studies. Most of the DIF models followed the power low variation function, linear function, and polynomial function as a function of strain rate, but the trends of DIF models significantly varied from each other based on the experimental results. A few DIF models are available considering the effect of end friction confinement, lateral inertia confinement, porosity, specimen dimensions, and fiber content, as these factors also significantly influence the dynamic strength of materials. Additionally, the value suggested for the transition strain rate significantly varied in compression as well as in tension based on the experimental study. The transition strain rate for dynamic strength in compression is predominantly observed to be above 10 s–1, whereas, for tensile strength, the transition strain rate is approximately 1 s–1, described that the tensile behaviour of concrete is more sensitive to the strain rate.