Behavior of Extended Shear Tabs in Stiffened Beam-to-Column Web Connections

Abstract

Single-plate connections, also called shear tabs, are an economical and efficient way to transfer load from one member to another, and are often found in steel-frame buildings. One type of shear tab is the extended shear tab, and it is unique in that the eccentricity of the bolt centroid to the weld centroid is greater than the 3½” allowed for standard shear tabs. This larger eccentricity develops a larger moment in the plate, sometimes requiring a thicker plate. There are instances, however, when this extra material cost is offset by other savings, and the use of extended shear tabs is economical. One such instance is when a beam or girder frames into the web (weak axis) of a column that is supporting a moment connection on its flanges (strong axis), as in a rigid frame. According to the AISC Manual of Steel Construction 3rd ed., an official design procedure does not exist for extended shear tabs. It is the goal of this Master’s Thesis to investigate different extended shear tabs in the aforementioned framing situation to determine their strength capabilities. A design procedure will be proposed and various shear tab connections will be designed using the proposed procedure. Full-scale testing of the connections will be undertaken in the laboratory to accrue experimental data and the connections will be simulated for analytical analysis using finite element models. The proposed procedure assumes a reduced eccentricity due to the stiffening of the continuity plates. The connection strength is contingent upon the capacity of the continuity plates, which must meet minimum requirements. The test results supported the hypothesis, but the results of the finite element models were insufficient for making any definitive recommendations.