INVESTIGATING THE ROLE OF EFFECTIVE PARAMETERS IN THE BEHAVIOR OF POST-TENSIONED CONNECTION BETWEEN STEEL BEAM AND COMPOSITE COLUMN

Many arrangements of beam-column connection have been considered since the start of steel construction. In the early times of steel construction, engineers provided bolted connections with different detailing of pinned and fixed connections. In the late 1950s welded-flange-bolted-web connections replaced earlier connections. Speed of erection and cost-efficiency were among the reasons that led to wide use of this connection detail. Prior to the major earthquake of Northridge, welded-flange-bolted-web connections were considered the most seismic resistant detail of any beam-column connection based on experimental work conducted at Lehigh University and University of California at Berkeley which proved their good cyclic behaviour. The experimental work showed that this connection can withstand high plastic rotations, especially for welded-flange-welded-web connection. These results led to widespread use of welded-flange-bolted-web connections in the 1980s. The Northridge earthquake caused extensive damage to many structures and changed the general idea about steel structures.The observation of the damage to the construction in 1994, with the Northridge earthquake, revealed that, unlike the expected behavior, in many cases, the brittle failure in the connections It happened at the of the Plastic rotations was much lower than the requirement, and in some cases, even when the elastic structures Have remained. According to the damages, the researchers proposed new connections, one of connections is the post-tensioned connection. Post-tensioned connections include high-strength steel strands for self-centering and energy dissipation to control plastic deformation.In this study, the numerical modeling of the post-tensioned connection was performed using Abaqus finite element software. In addition to verifying the accuracy of the modeling with the experimental results, 3 samples of the connection were modeled and Was investigated the effect of some parameters on the connection behavior under cyclic loading, this parameters including the use Angle and reinforced plate with greater length and width, the larger post-tensioning force, use the web angle. In the range of models of this paper, the results show that increasing the angle length and the width of the reinforcing plate increases the flexural strength, energy dissipation, and connection stiffness. In addition, an increase of 20 kn of post-tensioning force leads to an Increase connection power in the lateral force bearing to 6%. Use web angle as a new idea, leads to increased flexural strength, Increase connection power in the lateral force bearing, energy dissipation, and connection stiffness.