Study On The Bearing Capacity Of Tubular Damaged T-joints After Strengthed By Collar Plate

Under earthquake or live load,the tubular joints may have produced large plastic deformation and a certain degree of damage,which may eventually lead to the overall destruction of the structure.Therefore,it is especially necessary to strengthen the structure of the damaged in-service pipe structure.Among the many reinforcement methods,the collar plate reinforcement method is low in cost and convenient to use.This joints selects the method of using the collar plate to strengthen the joints.In this paper,five test members in the test were selected for finite element simulation to verify that the data obtained by finite element simulation can be used to study the influence of different damage degrees on the bearing capacity of collar plates reinforced.In this paper,the Bao-Wierzbickis damage criterion is used to analyze the circular tubular T-joints,and the damage parameters are added according to the damage criterion.The peak load results of the finite element simulation differ from the test results by approximately 3%.It can be concluded that the damage model,failure criterion and constitutive model used in abaqus are suitable for the study of static bearing capacity of circular tubular T-joints strengthened by collar plate under different damage degrees.According to the comparison between the finite element simulation results and the experimental results,it is determined that the results of the finite element simulation are reliable.52 models can be analysis.The static bearing capacity of the circular tubular T-joints under the condition of the damage degree,the size of the collar plate,the chord diameter and the chord thickness of the collar plate are studied.It is concluded that the larger the collar plate size,the ultimate bearing capacity of the damaged specimens using the collar plate is improved by about 22%-57%in the range of collar plate size 85mm to 130mm,and in the range of damaged degree 53%Δm to 200%Δmthe smaller the chord diameter,the ultimate bearing capacity of the damaged specimens is increased by about 12%-120%,and in the range of chord diameter 120mm to 194mm,and in the range of damaged degree 53%Δm to 200%Δm;the greater the wall thickness of the chord,the ultimate bearing capacity of the damaged specimens is increased by about 19%-78%in the thickness of the chord wall 4mm to 10mm,and in the degree of damaged 53%Δm to 200%Δm;under the same conditions,the greater the degree of damaged,the smaller the bearing capacity of the strengthened specimen in the degree of damaged 53%Δm to 200%Δm;the ultimate bearing capacity of damaged specimens is 7%-40%smaller than the ultimate bearing capacity of the directly reinforced specimens.Each model takes 9 measuring points and analyzes the variation of the equivalent plastic strain under different loads.The value of the measuring points in the plastic hinge area changes greatly,and the value of the equivalent plastic strain is smaller in the region farther from the plastic hinge.The position at which the specimens can be broken is at a measuring point where the equivalent plastic strain changes greatly.Compare the equivalent plastic strain of the model under different damage conditions.It is concluded that the collar plate reinforcement damaged model shows a good reinforcement effect;and the ultimate bearing capacity of the specimens can be increased by about 57%in damage degree 53%Δm after collar plate reinforcement.Finally,based on the formula of the compressive bearing capacity of the circular tubular T-joints strengthened by the collar plate under the axial force,the damage correction coefficientis proposed in the degree of damaged 53%Δm to 200%Δm.Therefore,it is predicted to predict the ultimate bearing capacity of T-joints under different damage levels within the damage range.