The connection between a steel beam and a concrete slab in the composite beams of many buildings or bridges is generally manufactured with headed studs. In the revised Japanese Industrial Standards in 2011, headed studs of diameters of 10 mm and 25 mm were added. However, a consideration of their mechanical properties is not sufficient.
The shear strength of headed studs is typically investigated via push-out tests; however, these tests are carried out under specific conditions, and the results of these tests are greatly affected by the test conditions. There have been only few studies on headed studs with diameters of 10 mm and 25 mm; however, there have been many studies on the mechanical properties of headed studs of other diameters, using push-out tests. Therefore, we collected test results on the shear strength that have been obtained from previous studies from other countries that performed push-out tests using headed studs. In this study, we define the subject of analysis, and attempted to discuss the tendency of shear strength comprehensively by investigating experimental data obtained through 1002 push-out test results.
We divide it into failure mode and type of slab; we focus on the tendency of the shear strength from the test results.
The shear strength of a headed stud in a solid slab was approximately equal to the product of the headed stud tensile strength and total cross-sectional area of the shaft component of the headed stud. The shear strength value is approximated because the results of the push-out test are influenced by the pure shear strength as well as the concrete strength. This tendency is especially prominent in case of failure of the headed stud. A similar tendency, although with variations, is observed in case of failure of concrete. The shear strength of a headed stud in a slab with a steel deck cut on the flange also shows a trend similar to the shear strength of a headed stud in a solid slab.
On the other hand, the shear strength of a headed stud in a slab with a steel deck across the flange showed a different tendency. It is less than the shear strength of a headed stud in a solid slab. Although specimens having a slab with a steel deck across the flange can be classified into specimens having a headed stud welded through a steel deck and specimens having a headed stud welded to the flange directly, their shear strength tendency was almost equal.
The shear strength of a headed stud with a diameter more than 25 mm in a solid slab gradually decreased with increasing diameter in both the failure modes.
Through a regression analysis of the test results, we classified the results into three types. The first is the test result for a headed stud having a diameter less than 25 mm in a solid slab or slab with a steel deck cut on the flange. The second is the test result for a headed stud having a diameter of more than 25 mm in a solid slab. The third is the test result for a headed stud having a diameter of more than 25 mm with a steel deck across the flange; the test result for a headed stud having a diameter of more than 25 mm and welded through a steel deck is not included in the evaluation. Therefore, three expressions are listed in Table. 2 using the shear strength and total cross-sectional area of the shaft component of a headed stud and headed stud tensile strength.
