Analyze the potential for employing internally welded steel plates to improve the shear response of high-strength self-compacting concrete-encased steel beams with large web openings

Openings in composite beams can be used to install ducts and utility pipes without increasing the story height. The shear strength of the composite beams is decreased as a result of these openings because the overall crosssectional area is reduced, which causes the concentration of stresses and the propagation of cracks around the opening corners. This study focuses on restoring the structural characteristics of composite beams cosisting of high-strength self-compacting concrete (HSSCC)-encased steel beams with large web openings utilizing internal steel plates and a steel box. An experimental program consisting of six composite HSSCC beams was prepared to investigate the effects of the length of the strengthening steel plates (320, 500, and 680 mm) on ultimate loads, stiffness, and absorbed energy. All steel plates had a constant thickness of 4.0 mm, while all composite beams have been tested under a four-point loading system. Additionally, a comparison was made between strengthening the HSSCC composite beams with steel plates and a steel box of the same length (320 mm). The installation of steel plates with a thickness of 4.0 mm and a length of 680 mm exhibited the highest ultimate load among all beams with web openings of 158.8 kN, with an improvement ratio of 116% with respect to the un-strengthened specimen with web opening. Moreover, a three-dimensional (3D) finite element model was created using the ABAQUS package to simulate the response of the experimentally tested specimens. Prior to performing a parametric study, the numerical model's results were verified using the experimentally recorded data. The parametric study examined the impact of increasing the thickness of the steel box and strengthening plates from 4.0 mm to 8.0 mm on the shear performance of HSSCC beams with large web openings.