Study On Seismic Behavior And Design Method Of Tube Constrained Steel Reinforced Concrete Column-Dog Bone Weakened Steel Beam Joints With Ring Beam

Steel tube constrained steel concrete structure has high bearing capacity,good ductility,convenient construction,and good fire resistance,and has been extensively studied and applied.Based on the previous research of the research group,in order to make the plastic hinge move outward,the cracking degree of concrete in the node domain is low,and make the joints have superior seismic performance,this paper proposes tube constrained steel reinforced concrete column-dog bone weakened steel beam joints with ring beam.The main work is as follows:(1)Design and finite element modeling of basic node.The finite element software ABAQUS is used to model and analyze the existing test nodes,including a circular steel tube confined H-beam column with ring beam and a dog bone weakened node.The failure mode,load displacement curve and ductility of the test node and the finite element model node are compared to verify the validity and correctness of the finite element model.At the same time,the failure mode and mechanical characteristics of the basic specimen under low cycle load is analyzed.(2)Based on the domestic and foreign research,the parameter analysis of the seismic performance of tube constrained steel reinforced concrete column-dog bone weakened steel beam joints with ring beam under monotonic loads and low-cycle cyclic loads is performed,and the monotonic loads are obtained.The load-displacement curve under the effect of bearing capacity and low-cycle repeated displacement load,analyze the influence of different parameters of steel beam weakening parameters,ring beam width,beam-column line stiffness ratio,column shear span ratio and column axial compression ratio on the seismic performance of the joint.The results show that:when the joint steel beam weakens by 0.33b_f≤a≤0.73b_f(b_f is the width of the flange of the steel beam);the weakened length of the steel beam is 0.6h_b≤b≤0.9h_b(h_b is the height of the steel beam section);The weakened depth of the beam is 0.20b_f≤c≤0.27b_f;the width of the ring beam is greater than the width of the steel beam flange bf;the beam-column line stiffness ratio is taken to be 0.16≤k_i≤0.54;the column shear span ratio is 5.1≤λ≤6.6;the axial compression ratio does not exceed 0.4.Within the limits of the above parameters,the new joint can keep the plastic hinge away from the beam end under low cycle repeated loads,effectively protecting the joint domain.(3)Based on the analysis of the influence of different parameters,the formulas for calculating the horizontal bearing capacity,bending bearing capacity and shear bearing capacity of tube constrained steel reinforced concrete column-dog bone weakened steel beam joints are put forward.Compared with the numerical simulation results,the error is less than 5%,which verifies the correctness of the formula.It can provide reference for the actual engineering and specification.