小高跨比实腹门式刚架平面内整体稳定性试验研究

STUDY ON GLOBAL IN-PLANE STABILITY OF PORTAL RIGID FRAMES WITH SOLID WEBS AND SMALL HEIGHT-SPAN RATIOS

采用位移控制加载法,对小高跨比实腹门式刚架在四点集中荷载作用下的平面内的弹性和弹塑性稳定性能进行了静力试验研究。试验模型Ⅰ用来研究刚架在平面内同时考虑几何非线性和材料非线性的稳定性能,试验模型Ⅱ、Ⅲ用来研究刚架在平面内仅考虑几何非线性的弹性稳定性能。吻合良好的试验和分析结果表明,刚架高跨比较小时,一般不发生传统理论所认为的反对称失稳模式,而是以对称失稳模式为主。通过大量的几何非线性有限元参数分析,给出了经修正的小高跨比刚架柱的计算长度系数。

Using the displacement loading method,a static experimental study is conducted o n the global in-plane stability of portal rigid frames with small height-span r atios with the four concentrated vertical forces being applied at the one-fifth points of the beam.The effects of material and geometrical nonlinearity were bo th considered in test model Ⅰ,but only the effect of geometrical nonlinearity w as considered in models Ⅱ and Ⅲ.The experimental results and its corresponding theorical analyses both show that the buckling modes are mostly symmetric,when the height-span ratio of the frame is smaller.The parametric analyses to globa l in-plane buckling of portal rigid frames with small height-span ratio are carr i ed out by using the geometical nonlinearity finite element analysis.The updated effective length factors for the columns of these potral rigid frames are given, it would be very useful in design practice.