薄壁焊缝SAWH钢管局部屈曲与受弯承载力

Buckling Behavior and Bending Resistance of Thin-walled Spirally-welded SAWH Tube

随着国内外基础建设规模日益加大,对大直径、大径厚比的螺旋焊缝钢管SAWH的需求不断深化。薄壁钢管结构服役时主要承受由弯曲形变引起的荷载,但国内对钢管受弯尤其是纯弯的研究较少,且尚未有试验对螺旋焊缝管与直焊缝管的抗弯性能进行比较与区分。文章针对大径厚比、大口径15根钢管考虑几何、材料非线性,进行抗弯性能研究并测量应变变形能力,为基于应变设计的规范提供方向。分析初始缺陷(残余应力、几何物理缺陷、径厚比、屈服强度等)对抗弯性能的影响。薄壁钢管受压区过早出现局部屈曲,显著降低了构件承载力、延性。残余应力对承载力影响可以忽略但强化了钢管的应变变形能力。屈服强度越高,受弯承载力越大,但变形能力随之下降。初始几何缺陷对抗弯承载力影响最大,要加强工厂预制后运输、放置、运营、维护等环节中的管理制度。

With the fast-paced development of infrastructure construction,the requirement of large tubes is continuously increasing.However,research regarding spirally-welded(SAWH)tubes,especially compared with large quantities of research with respect to longitudinal welded tubes(SAWL),is very limited.There is no direct comparison of buckling and deformation capacity between spiral welded tubes and longitudinal welded tubes.The main load of the thin-walled tube is bending due to earth load.Fifteen tubes are tested in the research.Through measuring the curvature(deformation capacity)of the tubes,indication based on strain-based design is provided.The effect of geometrical imperfection,residual stress,diameter to thickness ratio and yields trength on bending capacityiss tudied.Local buckling on compressed side significantly reduce the bending capacity and ductility.The deformation capacity slightly benefit from residual stress.The higher the yield strength the larger the bending moment but lower critical curvature.Initial geometrical imperfection is the most influentialfactortobendingresistance.Therefore,thetubeswhichistransportedtositeafter pre-fabricating should be carefully and seriously controlled in terms of the management of transportation,placement,application and maintenance.