Study on Bracing Member for Steel Member and Frame considering Coupled Buckling

本研究旨在说明支撑构件的结构特性和钢结构结构设计中极限状态的设计概念和准则。在支撑构件的设计上，考虑了构件与节点的耦合屈曲，分析的对象是支撑构件只受拉侧向屈曲的钢构件。首先，分析了影响支撑构件屈曲强度和极限状态变形能力的因素，数值分析是考虑侧向屈曲和局部屈曲的有限元方法。单元的概念用到了壳单元和梁单元。分析参数包括支撑刚度、支撑细部、梁截面和荷载条件，在对实心腹板构件的拉翼缘单独进行支撑时，不仅要考虑轴力，还要考虑弯矩。如果将弯矩视为受压翼缘横向扭转挠度引起的弯矩，则当屈服轴力的2.5%作为水平力F施加时，可视为支撑弯矩M=fh。因此，将约束内弦受拉构件的构件连接和连接到桁架构件时必须谨慎。反复加载对强度和变形能力的影响是降低这些能力的。节点的脆性破坏与构件端部应变水平有关，为避免节点宽厚比对屈曲强度的脆性破坏，建议在抗震设计中没有考虑弯矩重分布或延性的支撑要求。局部屈曲后，截面不对称，竖向荷载向平面外荷载发展非常显著。

The purposes of this study are to explain structural properties of bracing members and design concept and rule for limit state on structural design for steel structures. On the design of bracing members, the couple buckling on members and connection.The object for analysis is steel members having the bracing members on tension side only.Firstly, the factors that affect bracing requirements for buckling strength and deformation capacity on the limit state for design criteria.Numerical analysis is finite element method considering lateral buckling and local buckling. Concept of element are used shell element and beam element. Analytical parameters are bracing rigidities, bracing detail, beam section, and loading condition.When the tension flange alone of a solid web member is braced, it is necessary to pay full attention not only to the above mentioned axial force, but also to the bending moment. If the bending moment is taken as bending moment due to the lateral torsion deflection of the compression flange, it can be considered as bracing moment M=Fh when 2.5% of the yield axial force is imposed as horizontal force F.Therefor, due care must be exercised when joining and attaching members restraining inner chord members in tension to the truss members.The effects of repeated loading for strength and deformation capacities are decrease these capacities. Especially, on tension sides only bracing the effects are large.The relationships of brittle fractures on connection and buckling of member are related strain level of member end, To escape the brittle fracture at connection wide-thickness ratio are large within to buckling strength,The recommendations do not address the bracing requirements for moment redistribution or ductility in seismic design.After local buckling the cross section is unsymmetrical and vertical loads develop very significant out of plane loading components.