高圧3軸圧縮応力下におけるコンクリートの応力-ひずみ関係 : その2 高速載荷

Abstract

In order to clarify the strain rate effect on mechanical characteristics of concrete, rapid triaxial high compression tests and rapid hydrostatic loading tests are conducted for cylindrical concrete specimens in the same manner as the static tests in Part 1 except forloading rates. In the rapid loading tests, the loading rates are applied corresponded to average uniaxial strain rates (D1) ε_1=-1.44×10^<-3>/sec, (D2) ε_1=-2.40×10^<-2>/sec and (D3) ε_1=-2.54×10^<-1>/sec. The effect of strain rate magnitude on the initial elastic moduli and failure strength are discussed, then the rates of increase of them due to octahedral strain rates are expressed by empirical equations. The tangent elastic moduli, which are described below, are derived by introducing this effect to the static tangent moduli presented in Part 1. K^t=KO・κ(ε_<oct>)・α_v(ε_<oct>)-α_D(φ_d) G^t=GO・g(ε_<oct>, γ_<oct>)・β_v(ε_<oct>)・β_v(φ_d) in which, KO=initial bulk modulus, GO=initial shear modulus, ε_<oct>=octahedral normal strain, ε_<oct>=octahedral normal strain rate, γ_<oct>= octahedral shear strain rate, κ(ε_<oct>) and g(ε_<oct>, γ_<oct>) are the increase coefficients due to strain rates. φ_d is coresponded to φ defined by expanding failure curve due to strain rates. Then, α_v(ε_<oct>), β_v(ε_<oct>), α_v(φ), β_v(φ) and φ are given in Part 1.