In-Place Strength of Welded Headed Studs

I n designing welded headed studs, it is common practice to calculate strengths based on concrete failure and steel failure separately, and use the lesser of the two as the in-place strength. It is generally agreed that there are only minor differences between the various design procedures for determining the strength of welded headed studs based on steel failure. However, there are concerns that serious discrepancies occur in the different design methods used to calculate the strength based on concrete failure, These concerns stemmed from a comparative analysis of tension strength conducted by Klingner and Mendonca.' To resolve these conflicts, a task group under the auspices of the PCI Connection Details Committee studied the problem of tension strength based on concrete failure. As a result of this study, the Connections Committee has proposed a revision of the tension strength equation in the PCI Design Handbook.' The proposed revision, its justification and its impact on other aspects, such as group action, behavior under combined loads, and also an analysis of the direct shear strength, are given in this paper. Various analyses in this article focus on strengths as governed by the concrete failure; however, for the sake of completeness, the proposed design procedure includes an analysis of steel failure. The equations for steel failure are taken from the PCI Design Handbook. z As noted previously, these equations generally agree with other recomrnendations and, therefore, no revision is considered necessary at this time. The design procedure described herein is proposed as a replacement for the corresponding material in the PCI Design Handbook 2 and also for inclusion in the PCI Connection Manual' currently under revision, Although the paper focuses on welded headed studs, the design equations would also apply to