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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。
Thin-walled light steel rectangular tube truss girder by the upper and lower chord rectangular tube and Z struts by self-tapping screws connected, usually occurs when the local bending moment buckling damage, and the tension under the chord can not control the situation. In order to make full use of materials, reduce the project cost and facilitate the processing, a new type of thin-walled U-shaped lower light steel truss girder is proposed. Firstly, the static loading tests of three truss girders with different types of bottom chord effect on the failure mode, flexural rigidity and ultimate bearing capacity of the whole truss girder are studied. . Then, the finite element analysis of six model beams with different lower chord section, cross-sectional area and opening direction was carried out. The experimental results show that it is feasible to use the U-shaped lower chord instead of the lower chord of the rectangular cross-section, and the positive U-shaped cross-section is superior to the inverted U-shaped cross-section.