Study On Stability Behavior Of High-strength Steel Combined Pressure Bar

With the improvement of production technology and processing technology, highstrength and ultra-high strength steel are produced and gradually applied in the actualproject which is obtained good effect. However, when high strength and ultra-highstrength steel are used for compression bar, the stability bearing capacity will be theleading role, its advantage of "high strength" is unable to give full play.So the researchon how to improve the stability performance of compressive bar is very necessary andmeaningful.On the basis of research and application status about the stability performance ofhigh strength steel compressive bar and ordinary steel bar stability control at homeand abroad by this paper, high strength steel combined pressure bar using in spacestructure and two kinds of its construction practice(flange type and circular hoop type)are put forward, it is made up by high-strength steel core and constraints bucklingouter tube through a circular hoop or flange.Finite element model of single set hoop and three sets hoop combinedcompressive bar are established through general finite element software ANSYS,based on the correctness of the model, introduction of the initial geometric defects,under the consideration of geometric and material nonlinearity, high-strength ultimatebearing capacity of combined compressive bar are analied to explore the influence onstability performance about parameters of the core steel strength, slenderness ratio andstiffness ratio of the outer tube and the inner tube, the gap between outer and innertube。The analysis showed that combined compressive bar makes the high-strengthsteel material properties of core into full play, improving material utilization. The coresteel strength, slenderness ratio, stiffness ratio, the gap parameter has a differentinfluence on the stability bearing capacity of combined compressive bar, onlyreasonable choice for these parameters can maximize the effectiveness.The combined compressive bar has two different buckling modes which isdetermined by the stiffness ratio of outer and the inner tube. When the stiffness isrelatively small, the common instability mode generates; when the stiffness isrelatively large, the combination core alone instability mode generates. The analysisshows that the stability bearing capacity of core tube separate unstable modes islower.Finally, combined compressive bar is introduced into the planar structure systemand space structure system to explore analysis results which shows that the reasonablereplace makes this kind of structure to turn local strut stability failure mechanism into the local trolley intensity failure mechanism, improving the ductility of the structure,playing the strength of steel. However, due to combined compressive bar replacedonce, the load on welded joints which connected ordinary bar has increased, but it isstill safe based upon the specification which provided the ball joint estimationmethods to determine the welding ball size.