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

本文的研究目的是解释钢结构结构设计中支撑构件的结构特性以及极限状态的设计概念和规则。对支撑构件进行了设计，对构件进行了耦合屈曲和连接。分析的对象是仅在受拉侧有支撑构件的钢构件。首先，对影响支撑屈曲强度和变形能力的因素要求进行了极限状态下的设计准则。数值分析采用考虑侧向屈曲和局部屈曲的有限元方法。单元的概念采用了壳单元和梁单元。解析参数为支撑刚度、支撑细节、梁截面和加载条件。当对实心腹板构件单独受拉翼缘进行支撑时，不仅要充分注意上述轴向力，而且要充分注意弯矩。若将弯矩取为受压翼缘侧向扭转挠度引起的弯矩，则当屈服轴力的2.5%为水平力f时，可视为支撑弯矩M=Fh。因此，在将约束受拉内弦杆的构件与桁架构件连接连接时，必须谨慎。反复加载对强度和变形能力的影响是降低了这些能力。特别是，在张力侧仅撑持效果较大。连接处脆性断裂与构件屈曲的关系与构件端应变水平有关，为了避免连接处脆性断裂，宽厚比在屈曲强度范围内较大，建议没有解决抗震设计中对弯矩再分配或延性的要求。局部屈曲后截面不对称，竖向荷载在构件面外发展非常明显。

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.