Mutaz Al Hijaj, PhDDepartment of Civil and Materials Engineering, University of Illinois at Chicago
Extended shear tab connections has been introduced in the thirteenth edition of the American Institute of Steel Construction Manual to the structural engineering practice as an alternative to the single plate or as known the shear tab connections. The function of the extended shear tab connection is to transfer the shear force from the beam to the supporting member (column or girder). The main advantage of using extended shear tab connections is to avoid coping of beams in the vicinity of the joint to bring the beam close to the web of the supporting member. Previous studies investigated the behavior of extended shear tab connections for members, joined at right angle, experimentally and analytically. Skewed connections, in general, are commonly used in practice to frame members that their longitudinal axes do not meet at a right angle; the use of extended shear tab connections for skewed members eliminates the excessive beam ends cutting and modifications which makes this type of connections attractive to engineers and fabricators. This study investigates the behavior and design of different configurations of skewed extended shear tab connections using the finite element analysis software ABAQUS.
The study investigated three configurations of the skewed extended shear tab connections: 1) With the plate unstiffened and welded to supporting member web (flexible support), 2) With the plate unstiffened and welded to the supporting member flange (rigid support), 3) And with the plate welded to stiffener plates and supporting member web. To achieve the study goals, finite element analysis for orthogonal configurations were performed. Results were compared with their counterparts obtained from experimental investigation to verify the finite element models. Then, the models were skewed at different angles with results obtained and compared.
It was observed that for stiffened configurations and unstiffened configurations with rigid support, the connection bending and torsional behavior slightly affected by the connections orientation. On the other hand, for the unstiffened configuration with flexible support, the connection behavior significantly affected by the connection orientation, especially the torsional behavior.
A design procedure was proposed based on a parametric study that was performed for skewed extended shear tab connections based on results obtained from finite element analysis for 300 models with different configurations. The variable parameters used for this study are: plate thickness, the distance between the weld line and the bolt line, skewed angle, and number of bolts. These parameters were investigated in terms of the connection vertical displacement, plate twist along the bolt line, plate twist along the weld line, and the connection shear capacity. Based on the parametric study results, a specific design procedure for the skewed extended shear tab connections was proposed and compared with the current design procedure in the AISC Manual 14th edition. Modifications to the current connection lateral stability checks in the literature were addressed too.
Mutaz Al Hijaj, Ph.D. graduated from University of Illinois at Chicago (UIC) with a Doctor of Philosophy (PhD) degree in Civil Engineering. He graduated from Jordan University of Science and Technology with a Master of Science (MS) and Bachelor of Science (BS) Degrees in Structural Engineering. Al Hijaj has been a member in several engineering associations similar to the American Society of Civil Engineers (ASCE), American Concrete Institute (ACI), and the American Institute of Steel Construction (AISC). Furthermore, his research focuses on investigating special types of steel connections and steel towers performance. Mutaz’s passion is a deeper knowledge leading to development of better and safer steel structures.
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