Abstract
An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.
Highlights
Since the advent of engineered cementitious composites (ECC), scholars from various countries have carried out many studies on their basic mechanical properties, durability, structural applications, etc
Zhao analyzed the influence of different fiber content on the dynamic mechanical properties of UHTCC, and the results showed that the dynamic compressive toughening effect of steel fiber is more significant [22]
This chapter analyzes the experimental results of the biaxial dynamic compression test of ECC materials, explores the failure mode of the specimen, establishes the ECC biaxial failure criterion, and discusses the characteristic parameters of the specimen biaxial dynamic compression, including the peak stress of the specimen, peak strain, deformation modulus, compressive toughness, etc
Summary
Since the advent of engineered cementitious composites (ECC), scholars from various countries have carried out many studies on their basic mechanical properties, durability, structural applications, etc. The dynamic compression mechanical properties of ECC are numerically simulated, and the crack propagation and compression failure process of the specimen was simulated by Xu [24] These studies currently only explore the effects of biaxial or different strain rates on ECC’s mechanical properties. The text focuses on studying the dynamic strength characteristics and failure characteristics of ECC under constant lateral pressure within the strain rate range (10−4 ~10−2 s−1 ) considered by the seismic load. Via experiments and changes of the ECC specimens, the mechanical parameters are represented, such as the failure form, compressive strength, elastic modulus, peak strain, stress-strain curve, and other ECC specimens under biaxial dynamics under different constant lateral pressures. This paper provides necessary experimental data for the mechanical properties of ECC under biaxial dynamics
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