薄壁轻钢矩管桁架梁的优化

Optimization research of light-gauge tube truss beam

薄壁轻钢矩管桁架梁由上、下弦矩管与Z撑经自攻螺钉连接而成,通常会发生上弦矩管局部压屈破坏,而受拉下弦管起不了控制作用的情况。为达到充分利用材料,降低工程造价且便于加工的目的,提出了一种新型的薄壁U形下弦轻钢桁架梁。首先,通过3个采用不同形式下弦的桁架梁试件的静力堆载试验,研究了上下弦截面面积、刚度以及截面形式的不同对整个桁架梁破坏模式、抗弯刚度和极限承载力的影响。然后,对6个不同下弦截面形式、截面面积及开口方向的模型梁进行了有限元分析。试验及分析结果表明,采用U形截面下弦代替矩形截面下弦管可行,正U形截面受力性能优于倒U形截面。

The light-gauge tube truss beam is formed by connecting the upper chord,the lower chord,and the Z clip through screws.The failure of the tube truss beam is mainly due to the local buckling of the upper chord,not the tensile yielding of the lower chord.In order to make full use of the material,reduce project costs and manufacture the lower lord more easily,a new type of tube truss beam with U-shaped lower chord is proposed in this paper.Firstly,three tube truss beams with different forms of the lower chord are tested,the effect of upper and lower chord section form,sectional area and stiffness on failure mode,bending stiffness and ultimate bearing capacity of the whole truss beam are examined.Secondly,the finite element analyses of six tube truss beams are carried out,considering different section forms,sectional areas and opening directions of the lower chord.Testing and finite element analysis results haveverified the feasibility of using the U shaped lower chord,and the normal U shaped section is better than an upside down one.