Behavior of skewed extended shear tab connections part I: Connection to supporting web Mutaz Al Hijaj ⁎, Mustafa Mahamid Civil and Materials Engineering Department, University of Illinois, Chicago, United States abstract article info Article history: Received 29 March 2016 Received in revised form 27 August 2016 Accepted 30 August 2016 Available online xxxx The objective of this study is to investigate the behavior of skewed extended shear tab connections in which plate (shear tab) is welded to supporting member webs (flexible supports). To achieve the study goals, Finite Element Analysis (FEA) for orthogonal configurations of extended shear tab connections were performed using the finite element software, ABAQUS. To validate the finite element models, the FEA results were compared with experi- mental results obtained from experimental investigation by Sherman and Ghorbanpoor [19]. Then, finite element models for skewed connections at different angles were created, analyzed and investigated. It was observed that skewed and orthogonal configurations have the same failure modes, however, the shear tab's twist increases with increased connection orientation due to additional torsional moment transferred from the supported beam to supporting member. Additionally, it was observed that the connection's vertical displacement slightly decreases as connection orientation increases. Relationships between the shear tab twist and skewed angle as well as and the shear tab vertical displacement and the skewed angle were investigated. It was observed that plate twist-skewed angle relationship can be represented using a linear equation. This equation can be used to relate the shear tab twist of skewed and orthogonal connections. Finally, the shear tab's torsional strength equa- tion in the American Institute of Steel Construction (AISC) manual 14th edition [4] was modified to consider the additional torsional moment added to the shear tab due to the connection orientation. Published by Elsevier Ltd. Keywords: Extended shear tab Skewed connections Flexible supports Twist Torsional moment ABAQUS 1. Introduction Extended shear tab connection has been introduced in the AISC manual 13th edition [3] to the structural engineering practice as an al- ternative to the single plate or known as the shear tab connection. The function of this connection is to transfer the shear force from the beam to the supporting member (column or girder). The main advan- tage 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 these connections for members joined at right angles, experimentally and analytically. Sher- man and Ghorpanboor [19] studied the behavior of different configura- tions of extended shear tab connections experimentally; they proposed a design procedure that provides sufficient strength and ductility to transfer the shear force from the beam to the supporting member and accommodate the same end beam rotation as a simply supported beam. Their procedure formed the basis of the design section of the ex- tended shear tab connections in the AISC manual [3]. Thornton and Fortney [20] studied the lateral torsional stability of the extended shear tab connections; the authors showed that the eccentricity due to the overlap between the plate and beam longitudinal axes will cause torsional moment on the connection, and this torsional moment is resisted by two components: the plate torsional strength and beam tor- sional resistance due to the floor or roof slab. The authors proposed an equation that calculates the torsional capacity of the connection in order to determine the need of using stabilizer plates. Rahman et al. [17] presented a three dimensional model to study the behavior of the unstiffened extended shear tab connections. The study focused on two configurations: three bolts unstiffened beam-to-column web configura- tion, and five bolts unstiffened beam-to-column web configuration. The author concluded that the finite element models presented in their study is a powerful tool in addressing the failure of the unstiffened ex- tended shear tab connection in the plastic region. Mahamid et al. [15] addressed in detail the failure modes and analyses of the stiffened ex- tended shear tab connection. Finite element models were created using ANSYS, these models were compared and verified with experi- mental study done by Sherman and Ghorbanpoor [19]. The author ob- served five different failure modes in these connections: bolt shear, shear yielding of the plate, bolt bearing, twist in the shear tab, and web mechanism in the girder web. Mahamid et al. concluded that his model is accurate and unique in examining the behavior of the stiffened extended shear tab connections. Brusi and Jaspart [10,11] introduced Journal of Constructional Steel Research 128 (2017) 305–320 ⁎ Corresponding author. E-mail addresses: malhij2@uic.edu (M. Al Hijaj), mmahamid@uic.edu (M. Mahamid). http://dx.doi.org/10.1016/j.jcsr.2016.08.024 0143-974X/Published by Elsevier Ltd. Contents lists available at ScienceDirect Journal of Constructional Steel Research