Effect of the Failure Surface Inclination of Punching with Studs as Shear Reinforcement

This paper presents experimental and theoretical results for the pullout resistance of anchor studs embedded in concrete blocks with inclined planes that simulate punching. This type of reinforcement has been widely studied to combat punching between the slab–column connection, but little information is available about its effect on the region of the inclined shear plane. To simulate this situation, six concrete blocks were made with a single embedded stud; the inclination planes were varied (18°, 30°, and 45°). The effective heights were 50 and 75 mm, and the section widths were 300 and 500 mm. The theoretical analysis was carried out by comparing the estimated load obtained from analytical models found in the literature with the failure load of the tested specimens. The results showed that the inclination plane did not significantly influence the pullout loads of the studs for the studied effective heights, because the configurations generated by the failure surface of the concrete cone trunks tended to stabilize in tension. However, the series with the 30° angle had slightly higher failure loads. The variation in concrete compressive strength did not influence the failure loads, revealing that the concrete strength grade <40 MPa can be an economical alternative in the design of concrete blocks or slabs reinforced with inclined studs.