Rate dependence of ultra high toughness cementitious composite under direct tension

Abstract

Ultra high toughness cementitious composite (UHTCC) usually shows strain hardening and multiple cracking under static tension loads. In practice, structures could be exposed to high strain rates during an earthquake. Whether UHTCC can maintain its unique properties and provide high structural performance under seismic loading rates largely determines whether it can successfully fulfil its intended function. To determine the rate dependence of UHTCC, uniaxial tensile tests with strain rates ranging from 4×10 −6 s −1 to 1×10 −1 s −1 were conducted with thin plates. The experimental results showed that UHTCC had significant strain hardening and excellent multiple cracking properties under all the rates tested. The ultimate tensile strain lay in the range of 3.7% to 4.1% and was almost immune to the change in strain rates. The rate of 1×10 −3 s −1 seemed to be a threshold for dynamic increase effects of the first crack tensile strength, elastic modulus, ultimate tensile strength, and energy absorption capability. When the strain rate was higher than the threshold, the dynamic increase effects became more pronounced. The energy absorption capability was much higher than that of concrete, and the average ultimate crack widths were controlled below 0.1 mm under all rates. Several fitting formulas were obtained based on the experimental results.

Numerical investigation on dynamic performance of reinforced ultra‐high ductile concrete–ultra‐high performance concrete panel under explosion

“…ECC has high tensile strain capacity but normal strength. 13,32 In contrast, UHPC has high strength and elastic modulus but comparatively low tensile strain capacity. [9][10][11][12] It is advantageous to combine ECC and UHPC into a composite system to resist blast.…”

“…ECC has high tensile strain capacity but normal strength 13,32 . In contrast, UHPC has high strength and elastic modulus but comparatively low tensile strain capacity 9–12 .…”

“…Strain-hardening behaviors accompanied by multiple cracking can be easily obtained when ECC is subjected to static or dynamic tension. [13][14][15][16][17][18][19] The tensile strain capacity of ECC with polyvinyl alcohol (PVA) fiber remains 2%-5%. 14 To achieve higher tensile strain capacity, ultra-high molecular weight polyethylene (PE) fiber was adopted as ECC's reinforcement.…”

“…It is observed that ECC with PVA fiber at 0.1 s À1 exhibits a tensile strain capacity of 3.7%. 13 Additionally, when the tensile strain rate is 187.5 s À1 , the tensile strain capacity of ECC with PE fiber (i.e., UHDC) remains 1.31%. 26 Since the mechanical properties of ECC at high strain rate are satisfactory, drop weight tests were conducted on reinforced ECC panels.…”

“…Engineered cementitious composites (ECC) is a kind of fiber reinforced concrete. Strain‐hardening behaviors accompanied by multiple cracking can be easily obtained when ECC is subjected to static or dynamic tension 13–19 . The tensile strain capacity of ECC with polyvinyl alcohol (PVA) fiber remains 2%–5% 14 .…”