Analysis of failure mechanisms of Gerber half-joint specimens through digital image correlation technique

Reinforced concrete Gerber half-joints are characterized by D-Regions in which the de Saint Venant theory is not valid. Therefore, in the capacity assessment of existing Gerber half-joints, the correct assumptions about the stress fields and the strut-and-tie models play a crucial role. Digital Image Correlation (DIC) is an optical technique for the determination of displacements and strains of specimens subjected to mechanical actions. In this work, the DIC technique is applied within an experimental campaign aimed at identifying the nonlinear behavior of Gerber half-joints according to different construction details. The results obtained using the DIC technique allow to identify the shape of the compression fields (struts) and to predict the development of the crack patterns. Therefore, the outcomes are compared with the expected shapes of the strut-and-tie models and interpreted to analyze the different failure mechanisms oh the half-joints.