钢管轻集料混凝土空间桁架梁受弯承载力试验

Bending capacity test of lightweight aggregate concrete filled steel tube spatial truss beam

为了研究钢管轻集料混凝土空间桁架梁的承载力设计方法,进行了钢管轻集料混凝土空间桁架梁试件的纯弯加载试验,通过试件挠度和钢管表面应变分析,研究了桁架梁受弯承载性能。根据平截面假定并忽略腹杆的影响,对跨中截面进行受力分析,提出了空间桁架梁抗弯承载力的计算方法。研究结果表明:钢管轻集料混凝土空间桁架梁受弯过程中,腹杆受力较小,上下弦杆变形基本一致,跨中截面弦杆纵向应变分布基本符合平截面假定;桁架梁挠度超过L/50(L为跨度)时,弦杆和腹杆表面光滑均没有鼓曲现象,破坏模式为延性破坏;实测受弯承载力按正常使用极限状态取值,试验承载力取值与计算结果相差5%以内。

In order to study the bearing capacity filled steel tube （CFST） spatial truss beam, a design method of lightweight aggregate concrete lightweight aggregate concrete filled steel tube （CFST） spatial truss beam specimen was made to be tested. The bending capacity of specimen was studied through the analysis of deflection and strain of steel surface. Based on the plane cross-section assumption and neglecting the effect of web members, the stress at mid-span section of specimen was studied and calculation method of bending capacity was proposed. The results show that the web members keep relatively small force in the loading process. The deflection of upper chord members has the same tendency with that of bottom ones. The longitudinal strain distribution of chords at mid-span section obeys the plane cross-section assumption. When the truss girder deflection exceeds L/50, there is no buckling phenomenon on surface of the chord and web members, which indicates that it is ductile failure. According to the serviceability limit state, bending capacity value of the truss beam was taken. And the test value agrees well with the test result which the deviation is less than 5%. 2 tabs, 10 figs, 20 refs.