| Buckling-resistant braces are formed by enclosing the inner core members with external constraints,and yielding without buckling,so they have full hysteretic curves under reciprocating tension and compression loads,and the buckling-resistant braces have full hysteretic curves under reciprocating tension and compression loads.Compared with the traditional brace,it overcomes the disadvantage of fast buckling under compression,provides stable lateral stiffness and high bearing capacity,and the buckling-proof brace is used as energy dissipation brace [1].In the process of earthquake,the main structure enters the yield state before the main structure to dissipate the seismic energy.However,the buckling-proof brace currently used in our country is mostly steel plate concrete brace with high self-weight and high production cost.In this paper,a kind of all-steel buckling-proof brace is presented,which is anti-buckling.Curved bracing adopts square steel pipe as pipe casing structure(abbreviated as TinT),which is composed of larger diameter square steel pipe as restraint casing and smaller diameter forced inner core square steel pipe.At the same time,the external restraint stiffness and the strength at both ends of the inner tube are improved,and the mechanical performance of the inner tube is greatly improved by forming the strengthening position through the ribbed plate before and after extending the end of the restrained steel pipe in the outer part of the inner tube.The mechanical performance of anti-buckling braces is analyzed in detail by using the general finite element software ABAQUS.The main contents are as follows:In view of the unstable failure pattern of double moment tube full steel anti-buckling brace,the strength of double moment tube anti-buckling bracing outer tube is deduced in detail,and the formula for calculating the strength of double moment tube section form is derived.In this paper,the formulas of extruding pressure between outer tube and inner tube and bearing capacity of outer tube under the condition of local instability are studied,and the formula for calculating the thickness of outer tube is derived under the condition of local stability of double-moment tube anti-buckling brace.The research shows that the ratio of width to thickness and the ratio of width to width are important factors that affect the local stability of anti-buckling brace.Based on this,the width of the anti-buckling bracing section of double-moment tube is reasonably given.Thickness ratio limit to 8In this paper,the finite element software ABAQUS is used to study the mechanical performance of buckling-proof braces under nonlinear conditions.One of the importantfactors affecting the bearing performance is the friction force between the inner and outer tubes of the brace.The existence of friction causes the fixed end reaction of the support to be greater than that of the load end of the support.The extruding pressure between the two-moment tube with anti-buckling bracing is closely related to the width-thickness ratio of the inner tube section and the initial defect,and increases gradually with the increase of the two-moment tube.However,the bearing capacity of the outer tube of the anti-buckling brace decreases gradually with the increase of the constraint ratio and the thickness ratio of the bracing section.When the gap size is 2mm,the mechanical performance of the braces is the best,and three kinds of all-steel buckling-proof braces with different cross-sections are compared.The results show that the strength of the braces is better than that of the steel braces.The buckling-resistant brace with double-moment tube section has the highest uniaxial compressive bearing capacity,which is about 8% higher than the other two kinds of cross-section forms,and the buckling-proof bracing with square tube sleeve has the best hysteretic behavior.The buckling-resistant braces of other cross-section forms are increased by about 15%. |
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