Experimental study on the cracking behavior of anchorage zones

With the aim of studying the cracking behavior of anchorage zones of post-tensioning tendons, an experimental research has been performed. The experimental program included eight prismatic specimens with 265 mm × 265 mm × 580 mm and 300 mm × 300 mm × 600 mm, reinforced with combinations of spirals and stirrups. The studied variables included the cross-section dimensions and the amount of confining stirrups. In this study special anchorage devices were used in all specimens, which are commonly used in everyday practice. To be able to fulfill the loading protocol, concrete strains were measured. These values were also used to study the cracking loads and crack widths, and to assess the influence of the different studied variables, as well as the failure loads. Models from the literature were used to estimate the expected values for cracking loads. These values were compared with the experimental ones to verify their adequacy for the tested specimens. From the experimental tests, it can be concluded that the increase of the stirrup diameter leads to lower cracking loads. The increase of the cross-section dimensions results in an increase in the cracking load. Available theories for estimating the cracking load do not provide satisfactory predictions of the expected cracking load.