Experimental study on cyclic axial tensile mechanical properties of SAP-PVA fiber concrete at different temperatures

Abstract

This study conducted uniaxial cyclic axial tests on internally cured SAP-PVA fiber reinforced concrete specimens at different temperatures using an MTS universal hydraulic servo machine, obtaining the failure modes and uniaxial cyclic stress-strain curves of concrete with different mix proportions. Utilizing the experimental data, characteristic points of the cyclic stress-strain curves, including loading and unloading, were obtained for different SAP-PVA fiber reinforced concretes. Subsequently, the variations in mechanical parameters such as plastic strain and elastic modulus were analyzed, and the relationship between unloading strain, reloading strain, and plastic strain was investigated. Corresponding regression models for the relationship between plastic strain and loading and unloading strain were established, and the accuracy of the model was validated using various experimental data. The results indicated a continuous decrease in the secant elastic modulus and peak stress but increase in the peak strain of SAP-PVA concrete with increasing temperature, indicating a significant negative impact of high-temperature effects on the mechanical properties of concrete. As the cyclic load increased, plastic strain accumulated, and the cumulative relationship between unloading strain and plastic strain showed weak correlation with high-temperature effects. The unloading model parameters of SAP-PVA concrete were independent of temperature load and only influenced by the degree of damage. With an increase in material damage, the nonlinearity of the unloading curve increased. Compared to the unloading curve, temperature load significantly affected the nonlinearity of the reloading curve. This study revealed the cyclic tensile mechanical properties of SAP-PVA fiber concrete at different temperatures, providing experimental and theoretical references for the practical application and calculation of such concrete in engineering projects.