Compression Stress-Strain Curve Model of High-Strength Spiral Stirrup Confined Concrete

This paper aims to establish a stress-strain curve model for high-strength spiral hoop-restrained concrete that can be applied to different cross-sectional forms and different constraint conditions. Based on mathematical statistics methods, collect and process the axial compression test data of high-strength spiral reinforced concrete columns with 5 types of hoop reinforcement constraint forms under 2 cross-sectional forms from existing literature are processed. The material parameters of the collected test specimens are concrete strength of 35.2–83.07 MPa, hoop yield strength of 450–1318 MPa, volumetric reinforcement ratio of 0.48%–4.43%, and longitudinal reinforcement ratio of 0.45%–1.79%. Subsequently, regression analysis is conducted on the five characteristic parameters of the stress-strain curve to establish a model for the stress-strain curve of high-strength spiral confined concrete. Comparing the curve model in this paper with the experimentally measured stress-strain curves of the test components, it is concluded that the curve model in this paper has the ability to predict the behavior of high-strength spiral reinforced concrete circular and rectangular components under different constraint conditions. The results show that the proposed formulas for calculating the stress of hoop reinforcement, peak compressive stress, peak compressive strain, and ultimate compressive strain under peak compressive stress are more accurate. The established model of stress-strain curve for high-strength spiral hoop-reinforced confined concrete has a wide range of applicability, accurately predicts the behavior of structural tests, and is convenient for finite element analysis and engineering calculations.