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This paper presents an experimental study on the behavior of the load capacity of handcrafted studs symmetrically embedded in concrete reinforced with steel fiber. A total of eight blocks were subjected to pull-out tests. The main variables were stud head thickness (3.17, 4.76, 6.35, and 7.9 mm) and concrete type. The results showed no significant difference in the mean pull-out strength in both types of concrete mixtures: conventional and fibrous. Therefore, the effect of steel fiber addition tends to reduce the inclination plane of cracks, changing the mode of abrupt failure to more ductile. Moreover, in conventional concrete, the thickness th=7.93 mm (0.20 dh) lost about 15% of the pull-out strength compared to the thickness th=3.17 mm (0.08 dh); in contrast, it obtained a gain of 5% in concrete with the steel fiber. That is, a thickness of approximately 10% of the head diameter can adequately provide satisfactory results in embedment with or without the addition of the steel fiber for fc=35 MPa. In addition, the literature models were more conservative. Also, a modified concrete capacity design method was proposed, considering the head thickness and the empirical factor for concrete breakout strength adjustment, k=20. The results were satisfactory, with an average of 1.00 and a coefficient of variation of only 6% in steel fiber concrete. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study proposes a practical solution for installing anchoring elements on hard or old concrete surfaces to receive tensile forces. For this situation, where the anchorages will be postinstalled, there is often no depth in the concrete base that meets the minimum straight length of standard anchoring. Thus, the use of headed studs or hooked anchor bolts are the most recommended solutions, but the procedure for installing these elements is still the subject of experimental investigations. Then, the technique of postinstallation of headed studs in hardened concrete niches and the use of structural epoxy resin in the new-old concrete interface is presented. Additionally, the influence of the addition of steel fiber on the anchorage studs performance was also evaluated. [ABSTRACT FROM AUTHOR]

The existing wood-diaphragm-to-masonry-wall connections in unreinforced masonry (URM) buildings provided very little or insufficient resistance in past earthquakes. Recent strengthening techniques for the connections between URM walls and flexible diaphragms concentrate only on the installation of wall anchorages for out-of-plane tension forces and shear bolts for in-plane shear forces. Strengthened chord elements, however, are also essential parts of URM buildings to resist earthquakes. This paper proposes seismic rehabilitation techniques where steel angles are used as chord reinforcement. A practical design example is presented, where chord axial forces caused by in-plane diaphragm deflections and chord shear flows caused by transverse seismic forces are computed. The computed axial forces and shear flows are to be used in the design of the chord reinforcement and the chord shear connections, respectively. [ABSTRACT FROM AUTHOR]