鱼腹梁结构受力变形的解析解及合理预应力值的确定

Analytical solution of stress deformation of fish-bellied beam structure and determination of reasonable prestress value

作为一项内支撑新技术,预应力鱼腹梁钢支撑体系具有大跨度、大空间的优势,已广泛应用于基坑工程中,但关于鱼腹梁结构的受力变形特性及预应力值的研究还很少。为便于分析,本文将鱼腹梁结构简化成一次超静定的张弦梁结构,基于某些合理假定,推导得出鱼腹梁结构受力变形的解析解,并分析鱼腹梁跨度、矢高、上下弦刚度及预应力对上弦梁挠度的影响。取上弦梁挠度为零时的预应力值为合理预应力值,并与规范值比较,发现两者是等价的。采用有限元分析软件MIDAS/GTS模拟鱼腹梁实例并与解析解对比,结果表明:当预应力值不超过合理预应力值时,解析解和有限元结果吻合得较好,可供工程设计参考;但当预应力继续增大时,两者偏差很大,并分析了原因。最后,针对鱼腹梁结构的预应力施加情况,提出了几点有益建议。

As a new internal support technology,theprestressed fish-bellied beam steel support system hasthe advantages of large span and large spaceof,and it has been widely used in excavationengineerings.However,there are few studies on the stress-deformation characteristics and prestress value of the fish-bellied beam structure.For the convenience of analysis,the fish-bellied beam structure is simplified as one time static string beamstructure in this paper.Based on some reasonable assumptions,the analytical solution of the fish-bellied beam structure is derived,and the influence ofspan,vector height,upper,lower chord stiffness and prestress on the deflection of the upper chord beam are analyzed.Command the prestress value when the deflection of the upper chord beam is zero asthe reasonable prestress value,compared with the standard value,it is found that the two value are equivalent.The finite element analysis software MIDAS/GTS is used to simulate the fish-bellied beam example and compared with the analytical solution,The results show that when the prestress value does not exceed the reasonable prestress value,the analytical solution and the finite element result agree well;but when the prestress continues increasing,the deviation between the two results is large,and the reason is analyzed.Finally,some useful suggestions are put forward for the prestressing condition of fish-bellied beam structure.