Investigation of Effective Crack Propagation of Concrete Based on Size EffectWANG Xue-zhi~(1,2),SONG Yu-pu~1,ZHANG Xiao-gang~3,HUANG Zhi-qiang~1 (1.School of Civil and Hydraulic Engineering,Dalian University of Technology,Dalian 116024,China;2.Department of Civil Engineering,Liaoning Institute of Technology,Jinzhou 121001,China;3.State Key Laboratory of Durability of Concrete,Shenzhen University,Shenzhen 518060,China)According to character of procession of concrete material having size effect,effective crack propagation of concrete crack was investigated with size effect formula of fracture toughness,and formula of effective crack propagation was obtained based on size effect rule.Using this formula to analyze some experiment result,some conclusions were reached that the formula was suitable for single line soften model but not for double line soften model.concrete;effective crack propagation;size effect;soften model