Abstract：Several tests are conducted in which the concrete specimens are divided into two groups：the single-edge notched(SEN) and the double-edge notched(DEN) concrete beams. Both of the two groups of specimens are loaded under four point shear force and two different types of boundary conditions. The whole failure process of the specimens is shot with charge coupled device(CCD). From the speckle images，different failure phenomena are seen induding the propagation paths of cracks and final failure mode. The speckle images shot by the CCD are manipulated from which the displacement，strain and shear fields in strain horizontal and vertical directions in the surface of specimens are gained. Among the speckle images，some are picked out at certain intervals and compared with that before deformation in order to obtain diseplacement and strain fields. The evolution process of each field is gained by arrangind those fields to the time order. Comparing the displacement and strain fields gained at the place where the cracks start，it is shown that the magnitude of the horizontal and vertical displacements are close，and the values of the horizontal and vertical strains are in the same grade. The results demonstrate that the shear stress is not dominant in the zone near the notches. It also indicates that，though the sliding support is adopted，friction in the support is not reduced to a certain extend. Therefore the support should be treated carefully so as to get better results from four point shear test.
