Static and cyclic compressive behaviours of ultra-high performance concrete in cold regions

Abstract

The stress–strain behaviours of ultra-high performance concrete (UHPC) at varying temperatures are fundamental information for the design and numerical analysis of cold-region structures using UHPC. To obtain the stress–strain relationship and damage evolution of UHPC at low temperatures, a series of low-temperature compression tests were conducted. A total of 21 UHPC cubes and 26 prisms were tested under compression to evaluate the influences of temperatures (T = 20, −30, −60, and − 80 °C), height-to-width ratios (H/B = 1 and 3), and loading conditions (monotonic and cyclic). The test results revealed that the cubic/prism ultimate compressive strength (fcuT or fcT), modulus of elasticity (EcT), and peak strain (ε0T) under monotonic and cyclic compression increased with the decreasing T within 20∼ −80 °C. As T decreased from 20 to −80 °C, the fcuT, fcT, EcT, and ε0T of UHPC under monotonic loading increased by 30.8%, 56.7%, 16.5%, and 15.8%, respectively. The low-temperature increasing rate on EcT and ε0T were very close, but significantly lower than that of compressive strength. In addition, the decreasing T did not affect the plastic strain, stress deterioration ratio, endpoint strain, and stiffness degradation ratio of UHPC under cyclic loading. Through the regression analysis of experimental results, the low-temperature monotonic and cyclic stress–strain constitutive models were developed and validated. The validations against test results showed that the proposed models provided reasonable predictions on monotonic and cyclic σ-ε behaviours of UHPC at low temperatures.