腹杆内灌混凝土十字形圆钢管节点平面内抗弯性能试验研究

Experimental study of in-plane bending property of concrete filled brace circular section X-joints

对腹杆内灌混凝土十字形圆钢管节点在腹杆平面内弯矩作用下的极限承载性能进行了单调加载的试验研究。实施了6个不同截面几何参数的腹杆内灌混凝土十字形圆钢管节点平面内抗弯极限承载力试验。本文介绍了节点试验方案,描述了节点平面内弯曲破坏现象,给出了荷载—腹杆端位移曲线、弯矩—弦杆局部变形曲线、弯矩—转角曲线以及节点区域应变强度分布曲线,并将腹杆与弦杆外径比β、弦杆径厚比γ和腹杆与弦杆壁厚比τ对节点平面内抗弯极限承载力和抗弯刚度的影响进行了讨论。试验研究结果表明:γ和τ值最大的试件平面内抗弯刚度模式接近刚域模式,其余试件接近非刚域模式;在一定参数条件下,腹杆内灌混凝土的节点试件平面内抗弯承载力、初始抗弯刚度都随着β值的增大和γ值的减小而提高,提高的程度与β、γ具体大小有关,而τ值对抗弯承载力和抗弯刚度的影响不大;各试件在最大弯矩作用下,除τ值较大节点试件的腹杆上所有测点都保持弹性外,其余试件腹杆上测点则部分进入塑性;所有试件的弦杆测点均进入塑性;若实际工程中取欧洲规范弯矩计算值与腹杆全截面塑性弯矩计算值中的最小者计算节点抗弯承载力,则τ值较小节点试件的平面内抗弯极限承载力与理论弯矩相当,而τ值较大节点试件的平面内抗弯极限承载力低于理论弯矩,偏于危险,需要进行深入的弹塑性理论分析。

To study the in-plane bending property of concrete filled brace circular section X-joints under in-plane moment, six joint specimens of different geometry parameters 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 in the paper. The effect of/3, T and ~＂ on bending resistance and rigidity of the concrete filled chord X-joints was also studied. Results of these Itests show that mode of bending rigidity of joints with high value of T and r approach rigid zone, other joints approach non rigid zone under in-plane moment; As the value offl increases and value of T decreases, the bending resistance and rigidity of joints increase, while the value of ~＂ has little effect on bending resistance and rigidity of joints. All spots of brace foot of joints with large 7 value remain elastic, part spots of brace foot of joints with small ~＂ value enter plasticity, all spot of chord enter plasticity under maximal in-plane bending ; Calculated bending resistance values of joints adopting smaller values between Eurocode3 bending resistance values and full plasticity-section bending resistance is accurate for joints with small 7 value, but leans to the unsafe side for joints with large ^- value. Elastic-plastic analysis of in-plane property of the joints is needed.