摘要
双层柱面网壳的稳定承载能力通常由杆件失稳控制,而杆件中的缺陷对其临界荷载有显著影响。系统地研究了杆件缺陷、节点偏差及其二者耦合作用对不同矢跨比、不同网格数双层柱面网壳的稳定承载能力的影响程度与规律,并提出了确定杆件缺陷分布最不利分布模式的方法。主要得出如下结论:杆件中的缺陷(初弯曲、残余应力)可被等效为杆件弯曲缺陷,其形状可假设为正弦半波、幅值可取为l/400(偏安全);杆件缺陷对网壳承载能力的影响程度与网壳矢跨比、杆件长细比有密切关系,对矢跨比较大、杆件长细比较大的网壳的影响更为显著。在实际工程中,须考虑杆件缺陷的影响,否则会高估网壳的承载能力;杆件弯曲缺陷的弯曲方向会明显影响网壳稳定承载能力,对于研究的所有情况,最不利杆件弯曲缺陷的分布模式为Form4,由修正的一致缺陷模态法确定的Form1也可看作最不利杆件弯曲缺陷的分布模式,二者的极限荷载非常接近,而修正的特征缺陷模态法不能得到最不利缺陷的分布模式。对于研究的网壳来说,其稳定承载力对节点偏差不敏感。
The load-carrying capacity of double-layer cylindrical reticulated shell is usually determined by the buckling of members,and the imperfection of member has a major influence on member buckling load.The effect of member imperfection,nodal deviation and their couplings on load-carrying capacity of double-layer cylindrical reticulated shells with different rise-to-span ratios and grid numbers are systematically investigated in this study.Furthermore,the method to determine the most unfavorable distribution of member imperfection is developed.Based on the analysis results,the imperfections in member(e.g.,initial curvature of member,residual stress)can be equivalent to member bow imperfection.The shape can be treated as a half-sine curve,and the amplitude can be taken as l/400,which is on the safe side.The effect of member imperfection on load-carrying capacity of reticulated shell is closely related to riseto-span ratio and grid number of reticulated shell.The reticulated shell with larger rise-to-span ratio and slenderness ratio is more sensitive to member imperfection.In the design of real structure,member imperfection must be considered.Otherwise,the load-carrying capacity will be overestimated.The load-carrying capacity of imperfect reticulated shell is apparently influenced by bending direction of bow imperfection.Form4 is the most unfavorable distribution of bow imperfection for all cases considered.Furthermore,the ultimate loading of reticulated shell with Form1 of bow imperfection,which is obtained by the modified consistent imperfection method other than the modified eigenmode imperfection mode method,is almost equal to the one with Form4 of bow imperfection.The load-carrying capacity of reticulated shell considered in this study is not sensitive to nodal deviation.
作者
肖姚
李会军
韩健
XIAO Yao;LI Huijun;HAN Jian(Collge of Water Resources and Architectural Engineering,Northwest A&F University,Yangling 712100,China)
出处
《建筑钢结构进展》
CSCD
北大核心
2020年第5期64-77,92,共15页
Progress in Steel Building Structures
基金
National Natural Science Foundation (51408490)
the Fundamental Research Funds for the Central Universities(2452020168)
Training Programs of Innovation and Entrepreneurship for Undergraduates(201710712046)。
关键词
双层焊接球柱面网壳
杆件缺陷
节点偏差
耦合影响
承载力
double-layer cylindrical reticulated shell with welded spherical node
member imperfection
nodal deviation
coupling effect
load-carrying capacity
