Effect of Testing Method and Strain Rate on Stress-Strain Behavior of Concrete

TLDR

Concrete flexural behavior differs from direct tension behavior. The study investigates how testing method and strain rate affect concrete tensile behavior. Concrete specimens were tested under direct tension and four‑point loading at strain rates from 10⁻⁶ to 10⁻³ s⁻¹, and a dynamic increase factor and continuous damage model were employed to predict strain‑rate effects. Peak stresses rise with strain rate, more strongly for direct tension than four‑point loading, and the dynamic increase factor and damage model accurately predict the stress‑strain curves.

Abstract

The flexural behavior of concrete is often different from its behavior under direct tension. This paper presents an experimental program aimed at the testing method and strain rate effects on the tensile behavior of concrete. Concrete specimens were tested with different testing methods (direct tension and four-point loading) and four strain rates (10−6, 10–5, 10–4, and 10−3 s−1). The results show that the peak stresses increase with an increase in the strain rate; the strain rate dependence of the peak stress is stronger for direct tensile specimens than for four-point loading specimens. The dynamic increase factor is expressed as a function of the strain rate and highly stressed volume method. The continuous damage model is also used to predict the strain rate effects on the ascending stress-strain behavior of concrete. Using the model parameters for the stress-strain curve of concrete at a static strain rate, the stress-strain curves of concrete for dynamic strain rates in four-point loading and direct tension are satisfactorily predicted.