الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Usage of Circular Hollow Section (CHS) has recently become widely spread, due to their large rigidity and stiffness under various types of loads. Tubular joints could be used for several categories of steel structures such as steel towers, offshore structures,
and external facade that are susceptible to be subjected to repeated load (cyclic load). Investigation of cyclic load effect on CHS T-joints is represented in this research.
Experiments were conducted on eight specimens, two specimens on unreinforced
and the rest on reinforced, adopting different methods (doubler, collar and stiffener). Each reinforcement was established on two specimens different in brace to chord diameters. Hysteresis curves were extracted from experiments to help obtaining the S curve, ultimate strength, ductility and energy dissipation. As a result, the existence of doubler has enhanced the ultimate strength in tension and compression cycles by 50% and 100% respectively. Improvement in connection reinforced with collar was 60% for both tension and compression cycles. Enhancement in connection with stiffener was larger in the ultimate tensile strength than the compression strength. Ductility and
energy dissipation has been enhanced in connection with the collar more than that reinforced with doubler.
Finite Element Model (FEM) has been verified with experiments, and the FEM
results were in favorable agreement with the experimental findings. Parametric study was conducted on four types of joints with change in geometry parameters (α, β, and τ). Tension and compression capacities were calculated for unreinforced and reinforced joints observing the effect of geometry parameters on joint’s capacity and
energy dissipation. The existence of collar enhanced the capacity of joint up to 50-70% and energy dissipation by 67%. Positive and negative capacities could be driven from a formula extracted from a regression analysis performed on 19 FEM for each type.