有限要素法による 3 次元コンクリート構造物の弾塑性解析 (軸対称PCPVへの適用)

Abstract

An orthotropic elasto-plastic material in which elastic modulus and Poisson's ratio may be defined based on those of uniaxial stress-strain characteristics is assumed for the concrete. Three-dimensional stress-strain relationship matrix [D_<ep>] is derived from that of the anisotropic elastic body and expressed in the form; [D_<ep>]=[A_p]^T{[D]+[H_p]}[A_p] Where [D] is the stress-strain relationship matrix of the homogineous elastic body. [A_p] and [H_p] are related to the changes of elastic tangent modulus and Poisson's ratio respectively. The element stiffness matrix may be obtained by using [D_<ep>] instead of [D]. As an application of this method to the axisymmetric body, ultimate pressure analysis of the prestressed concrete pressure vessel is described by using the technic of elastic stress analysis by the F.E.M.. In the numerical procedure of the computor program, it is assumed that when a principal tensile strain exceeds the critical tensile strain and tensile stress remains in the same direction, the element is able to crack and stresses on the crack are released. When a compressive strain exceeds the critical compressive strain the element stiffness is treated to fail completely. The numerical results are discussed with the 1/40th scale model test results, and it is assured that the method is valid to consider the behaviors of the PCPV beyond the elastic range.