主管中灌混凝土平面X形圆钢管混凝土节点平面内抗弯性能试验研究

对主管中灌混凝土平面X形圆钢管混凝土节点在支管平面内弯矩作用下的极限承载性能进行单调加载的试验研究。实施6个不同截面几何参数的主管中灌混凝土平面X形圆钢管混凝土节点平面内抗弯极限承载力试验。介绍了节点试验方案,描述了X形圆钢管混凝土节点平面内弯曲破坏现象,给出荷载-支管端位移曲线、弯矩-主管局部变形曲线、弯矩-转角曲线以及节点区域应变强度分布曲线,并将支主管外径比β、主管径厚比γ和支主管壁厚比τ对节点平面内抗弯极限承载力和平面内抗弯刚度的影响进行讨论。试验研究结果表明:主管灌混凝土后并没有在主管中形成明显的刚域;在一定参数条件下,主管中灌混凝土的X形圆钢管混凝土节点平面内受弯极限承载力、抗弯刚度均随着β、τ值的增加和γ值的减小而提高;各试件在最大弯矩作用下,所有试件的支管根部测点都进入塑性,主管上大部分测点保持弹性状态;主管中灌混凝土对圆钢管节点平面内抗弯极限承载力有一定的提高,在一定参数条件下提高甚至达到48%,但若实际工程中取欧洲规范弯矩值与支管全截面塑性弯矩值中的最小者计算节点抗弯承载力,在一定的钢管几何参数下不一定是安全的,需要进行深入的有限元参数分析。

Experimental study on the in-plane bending property of concrete filled chord circular section X-joints

To study the in-plane bending property of concrete filled chord circular section X-joints under in-plane moment,six parameter joint specimens of different geometries were tested under in-plane moment in brace.The test procedure,joint failure phenomenon,in-plane moment in brace-global displacement curves,in-plane moment in brace-deformation of chord tube,moment-rotation curves and strain distribution curves were presented.The effect of β,γ and τ on the bending resistance and rigidity of the concrete filled chord X-joints was also studied.Results of these tests show that the concrete in the chord does not form an obvious rigid zone.As the values of β,τ increase and the value of γ decrease,the bending resistance and rigidity of joints increase.All of the brace foot entered plasticity,while most of chord still kept elastic,thus the concrete of chord obviously improved the bending resistance of the joints,and the bending resistance was increased by 48% at most.Calculated bending resistance values of joints assumed smaller values between Eurocode 3 bending resistance values,and full plasticity of section bending resistance was on the unsafe side for certain geometric parameters.Finite element parametric analysis and design formula of compressive ultimate capacity for the joints is needed.