轴向冲击下C型冷弯薄壁钢构件的屈曲失稳研究

发布时间：2018-04-18 06:58

本文选题：C型冷弯钢构件 + 落锤实验　；参考：《宁波大学》2017年硕士论文

【摘要】：冷弯薄壁钢构件由于重量轻、强度高、便于加工,能批量化生产,已经越来越广泛地用于各种高层建筑作为承重结构中,当然也会被用于高地震、大风压或可能遭受冲击载荷的军事工程。然而,国内外对于常见的开口薄壁冷弯钢构件(C型、Z型等)在动态冲击载荷作用下的失稳和失效研究却非常缺乏,这一点也影响该类结构在设计、施工尤其是灾后安全使用的评估工作。目前国、内外冷弯钢结构设计规范等都没有对承受冲击载荷工况下该类结构的设计做出过明确的条款说明,故而研究开口薄壁冷弯钢构件在承受冲击载荷下的失稳和受损伤后试样的剩余承载能力有很大的实际工程意义。首先,本文对选取的冷弯薄壁C型钢构件进行了系列在不同冲击速度下的动态落锤轴向冲击试验,并结合高速摄影仪和Vic-2D软件分析冲击过程中试样的屈曲发展过程、轴向位移曲线和残余破坏形态。其次,采用商业有限元软件Abaqus建立了能够反映冲击过程的有限元模型,考虑了应变率强化效应和几何非线性,同时,基于广义梁理论对有限元屈曲模态进行分析识别的基础上在后续非线性屈曲分析中引入了合适的模态组合作为初始缺陷。最后通过构件腹板顶部的轴向位移时程曲线,锤头速度时程曲线以及试样屈曲残余变形进行了验证,并得到了以下结论:冷弯薄壁槽钢在受到冲击载荷时,构件自身对初始缺陷异常敏感且在较高的冲击能量加载的过程中,卷边将率先屈曲从而失去对翼缘的加劲作用,卷边破坏严重,随后引起翼缘、腹板承载能力下降,致使构件整体发生屈曲,因此,在可能受到冲击载荷的实际工程中,若使用的槽钢构件尤其在卷边处存在初始缺陷,将是一个严重的隐患;该尺寸槽钢试样在受到10m/s及以上冲击速度的情况下,呈现向高阶非对称畸变屈曲模态跃迁的迹象;随着冲击速度的提升,构件的动态屈曲临界载荷也会相应提升;应力波的传播在C型钢构件在冲击载荷作用下的动态失稳中起到主要的作用。最后,利用WAW-2000型微机控制电液伺服万能试验机对受过冲击载荷的槽钢试样和完整试样进行轴压破坏实验并进行对比,分析了槽钢构件的残余变形形态,荷载位移曲线,并得到了冲击能量与构件剩余承载能力的关系。
[Abstract]:Because of its light weight, high strength, easy processing and mass production, cold-formed thin-walled steel members have been more and more widely used in various high-rise buildings as load-bearing structures, of course, they will also be used in high earthquakes.Military engineering with high wind pressure or potential impact load.However, the research on the instability and failure of common thin-walled cold-formed steel members, such as C type and Z type, under dynamic impact load, is very scarce, which also affects the design of this kind of structure.Safety assessment of construction, especially after disaster.At present, the code for design of cold-formed steel structures inside and outside of China has not made a clear provision on the design of this kind of structures under impact load.Therefore, it is of great practical significance to study the instability of thin-walled cold-formed steel members under impact load and the residual load-bearing capacity of specimens after damage.First of all, a series of dynamic drop weight axial impact tests are carried out on the cold-formed thin-walled C-shaped steel members under different impact velocities, and the buckling development process of the specimens during the impact process is analyzed by using high-speed photography and Vic-2D software.Axial displacement curves and residual failure patterns.Secondly, the commercial finite element software Abaqus is used to establish a finite element model which can reflect the impact process. The strain rate strengthening effect and geometric nonlinearity are considered.Based on the generalized beam theory, the finite element buckling modal analysis is identified, and the suitable modal combination is introduced as the initial defect in the subsequent nonlinear buckling analysis.Finally, the axial displacement time history curve at the top of the member web, the velocity time history curve of the hammer head and the residual deformation of the specimen buckling are verified, and the following conclusions are obtained: the cold-formed thin-walled channel steel is subjected to impact load.The member itself is very sensitive to the initial defect and in the process of high impact energy loading, the crimping will buckle first and lose the stiffening effect on the flange. The edge of the flange is damaged seriously, and then the flange is damaged, and the load carrying capacity of the web plate decreases.As a result of the overall buckling of the member, it is a serious hidden trouble if the channel steel member used in the actual project may be subjected to impact load, especially at the edge of the crimping.Under the impact velocity of 10m/s and above, the specimens of this size show signs of transition to higher-order asymmetric distortion buckling mode, and the critical load of dynamic buckling of the member will be raised accordingly with the increase of impact velocity.The propagation of stress wave plays an important role in the dynamic instability of C section steel member under impact load.Finally, WAW-2000 microcomputer controlled electro-hydraulic servo universal testing machine is used to test the axial compression failure of channel steel specimen and intact specimen under impact load, and the residual deformation pattern and load displacement curve of channel steel member are analyzed.The relationship between the impact energy and the residual bearing capacity is obtained.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU392.1

【参考文献】