On Galerkin Boundary Element Method And Its Application For Softening Analysis Of Structure

The subject of Galerkin boundary element method and its application for softening analysis of structure is researched. Some results is obtained in this paper as follow:A symmetric boundary-element method based on weighted residual Galerkin approach is used in elastoplastic and softening analysis and its computational implementation for two-dimensional homogeneous problems is described. A new loading increment control method is suggested to deal with the local buckling. Instead of traction(force)-controlled method and displacement-controlled method, this method can deal with the whole process of structure softening problems. A numerical integral scheme of softening and elastoplastic constitutive relation was developed. Using the associated plastic flow law, regarding the elastic and plastic strain as vectors in the strain/stress .space, one can take the projection of the strain vector in the normal direction of the yielding surface as its plastic part. Considering this, the elastic strain and the position of the elastic stress on the yielding surface can be modified in every step of strain increment. This numerical integral scheme of constitutive relation can be adopted for many yield criteria. As an important creative work, a discrete interpolation method named "Quasi-High Order Element Method" is established, its advantage is improving efficiency and accuracy of numerical computation greatly. Through this method, high order element can be used in elastoplastic and softening analysis by Galerkin boundary element method. To validate numerical techniques established in this paper, some examples are given. As an engineering application, the safety of a hydraulic dam is analysed.