Research On Mechanical Behavior Of H-shaped Beam To Square Tube Column Joint With Cast Steel Stiffener

Steel frame structure has advantages such as light weight,flexible layout,good seismic performance,convenient installation and ease of standardization of components.It has been wildly used in multi-story and high-rise buildings.The performance of the frame joint has great effect on the structural behavior of the steel frame structure.Since the square tube column has sealed section,the construction of the joint for H-shaped beam to square tube column connection has great difference with the joint for H-shaped beam to H-shaped column.The beam-column joint is a complex part of the design and construction of square tube column frame structure.The performance of the joint has significant effect on the performance of the frame structure.H-shaped beam to square tube column joint with cast steel stiffener is a novel rigid beam-column joint for frame structure.Cast steel stiffener is used as stiffener in joint and formed the beam to column connection.The joint has clear loading transmission,reliable performance,simple structure and convenient construction.In this paper,theoretical analysis,experiment test and numerical simulation are conducted for the research on mechanical behavior of H-shaped beam to square tube column joint with cast steel stiffener.1)The bearing capacity theory based on the deformation compatibility condition is proposed in this paper by analyzing the loading transmission of the joint.It was known by analyzing that the load of the joint is mainly beard by the cast steel stiffener rings,only negligible load is beard by column.The bearing capacity formula is proposed.The formula uses the bearing capacity of the cast steel stiffener as the bearing capacity of the joint.2)Twelve specimens of H-shaped beam to square tube column joint with cast steel stiffener were tested under monotonic tensile load.The findings are that the tensile bearing capacity of the joint with cast steel stiffener depends on the ring of cast steel stiffener.The tensile fracture happens at the ring of the cast steel stiffener when the joint fails.The thickness of square tube column has little influence on the bearing capacity of the joint.The load-bearing capacity of the joint increased by 10% to 15% for the concrete filled in the square tube column.The length and construction of the welding connection between square tube column and cast steel stiffener have few influences on the load-bearing capacity of the joint.No significant failure at the welding connection between square tube column and cast steel stiffener.3)Eleven full-scale cruciform specimens of H-shaped beam to square tube column joint with cast steel stiffener were tested under static monotonic load.Research results indicated that the joint has sufficient moment bearing capacities and deformation performance.The rotational stiffness of the joint could meet the requirement of the rigid connection for steel frame.The joint has excellent static behavior and proved to be a novel type of steel frame rigid connection.The moment load of the joint is mostly borne by the cast steel stiffener.The concrete filled in the square tube column helps to increase the moment bearing capacity and the rotational stiffness of the joint.Parametric nonlinear finite element numerical simulation of H-shaped beam to square tube column joint with cast steel stiffener under static load is conducted.The corrected bearing capacity formula suitable to the H-shaped beam to concrete filled square tube column joint with cast steel stiffener is presented based on the results by simulation.4)Parametric nonlinear finite element numerical of H-shaped beam to square tube column joint with cast steel stiffener under static load is conducted.Results by numerical are agreed well with the results by experiment test.Results by numerical verify the bearing capacity theory based on the deformation compatibility condition.The corrected bearing capacity formula suitable to the H-shaped beam to concrete filled square tube column joint with cast steel stiffener is presented based on the results by numerical.5)A series of six full-scale cruciform H-shaped beam to square tube column joint with cast steel stiffener specimens was tested under cyclic loading.A parametric numerical study based on the test results was also conducted.The joint showed excellent deformation performance and energy dissipation coefficients in the test,the beam or column showed no failure.It is proved the novel joint is suitable for the steel frame structures in the seismic region,and the joint can decreased the risk of the progressive collapse of the frame.The hysteretic curves of beam-column joint specimens with cast steel stiffeners without concrete filled are plumpness,and the hysteretic curves of specimens with concrete filled are pinching.Stiffness degradation is shown in each specimen.The maximum moment resistance of the joint with concrete filled in the column increased from 10 to 30% compared with that of the joint without concrete filled in the column on average.Parametric numerical study proved the beam-column joints with cast steel stiffener have great energy dissipation coefficient,deformation performance and excellent seismic behavior.