PREDICTING FRACTURE BEHAVIOR OF CONCRETE STRUCTURES BY DESIGNING QUANTITATIVE GEOMETRIC STRUCTURAL SPECIMENS

A structural geometry parameter a_e, which can reflect the coupling effects of specimen size, crack length, front & back boundaries and loading types, is used to replace the absolute size W used in the traditional size effect theory to explain the microphysical mechanism of the size effect of strength and fracture characteristics. The model and associate method for determining the true fracture and strength parameters of concrete without size effect are developed and established by two groups of design specimens with a_e ratio of 3, not restricted by the selection of specimen size, crack length, loading type and other conditions under laboratory conditions. Based on the proposed method, the transformation curves of different fracture modes of concrete are established for the designed specimens with a_e ratio equal to 3, and a ±15% variation of the curves can cover the test results of the specimens under laboratory conditions; Taking the equivalent area of the actual structure into the proposed analytical formula, the peak load of large-size actual structures can be predicted. Link is built to determine the real material properties of concrete in field conditions using laboratory results, and the goal of accurately predicting concrete fracture characteristics using quantitative laboratory specimens with different structural geometry parameters can be realized.