1[1] Hillerborg A, Modeer M and Petersson P E. Analysis of crack f ormulation and crack growth in concrete by means of fracture mechanics and finit e elements[J]. Cement and Concrete Research, 1976,6:7 73 ~782.
2[2] Roelfstra P E, et al. Numerical method to link strain softening with fai lure of concrete[C]. Fracture Toughness and Fracture Energy of Concret e, Elsevier. 1986.163~176.
3[3] Hawkins N M, et al. Hybrid Analysis of Fracture Process of Concrete, Fra cture of Concrete and Rock[C]. Elsevier Applied Science, 1989.297 ~306.