双层柱面网壳设计研究

通过４９ｍ　× １００ｍ,４５ｍ×８１ｍ,６０ｍ×１１７ｍ三个双层柱面网壳在不同结构形态、各种支承条件及轻、重屋面荷重下的计算分析,对柱面网壳结构选型、计算假定等作了详尽的论述;并讨论了对于柱面网壳支座水平推力的处理、温度应力对大跨度柱面网壳的影响等不能回避的问题,指出网壳支座与平板网架支座节点的不同,提供了常见支承条件下网壳支座的设计思路和作法。     

铝合金单层柱面网壳结构稳定性能研究

通过MIDAS有限元软件对铝合金单层柱面网壳结构稳定性进行了弹塑性稳定分析,分析了矢跨比、结构网格密度、边界支承条件和初始缺陷对柱面网壳整体稳定承载力的影响。根据不同影响因素共设计了数百例柱面网壳,并对其进行有限元分析,为铝合金单层柱面网壳结构整体稳定设计提供了一定的理论基础。     

双层柱面网壳选型与设计

本文通过45m×81m双层柱面网壳工程实例，在多种方案下的计算分析，对柱面网壳结构造型、计算假定和结构分析方法等作了较全面的概括；对于温度应力影响、支座水平推力处理等不可回避的问题也作了较详细的论述；指出网壳支座节点与平板网架支座的不同点，并通过实际工程支座的设计，提供了网壳支座的设计思路和方法．     

铝合金球面网壳结构弹塑性稳定性研究

对铝合金球面网壳结构弹塑性稳定性能进行有限元研究,分析了网壳的失稳模态、变形、应力分布和极限承载力。通过参数分析,了解跨厚比、矢跨比、杆件长度、材料非线性、荷载分布模式、支承条件和初始缺陷对铝合金球面网壳整体稳定承载力的影响。最后,提出了铝合金球面网壳稳定承载力的安全系数设计方法。结果表明:对于铝合金球面网壳,JGJ 7—2010《空间网格结构技术规程》给出的安全系数K=4.2偏大。     

某大跨度干煤棚网壳结构设计及优化研究

以某大跨度干煤棚网壳结构为研究对象,在柱面双层网壳结构方案的基础上,提出采用折柱面双层网壳结构的优化方案,通过建立多个计算模型,分析对比不同折线坡度、网壳厚度对结构承载力和用钢量的影响,确定最优的结构几何参数。研究结果表明,在相同用钢量的情况下,折线坡度为9.16%、网壳厚度为4.4m左右时,折柱面双层网壳结构极限承载力比柱面双层网壳结构提升27.3%。     

深圳湾体育中心钢结构屋盖稳定性能研究

深圳湾体育中心钢结构屋盖为超大跨度空间结构,由单层网壳、双层曲面网架及竖向支撑系统构成。单层网壳为复杂的空间曲面网格结构,采用箱形弯扭构件编织而成的四边形网格构成。首先基于弹性屈曲分析方法,深入地研究了结构的失稳模态和成因;其次,通过全过程跟踪结构的平衡路径,对结构非线性弹性和弹塑性稳定性能进行了研究,揭示了该类网壳结构的特殊失稳机理,提出针对该工程网壳结构的稳定设计准则;最后,采用有限元对网壳的局部稳定进行了分析,基于分析结果给出了网壳构件的计算长度系数取值。     

三心圆柱面双层网壳结构整体稳定性分析

以某电厂干煤棚三心圆柱面双层网壳结构为例,建立结构稳定有限元分析模型,考虑、久荷载+全跨可变荷载""永久荷载+半跨可变荷载" 2种分析工况,取各工况作用下的一阶屈曲模态作为结构的初始几何缺陷分布模态,采用仅考虑几何非线性和考虑几何、材料双重非线性的全过程分析方法,计算得到各模型的荷载-位移曲线和稳定承载力系数,结果表明"永久荷载+全跨可变荷载"工况对结构稳定更为不利;随着缺陷幅值增加,结构稳定系数下降不多,说明初始几何缺陷对结构稳定性的影响较小。结构失稳主要由部分杆件进入塑性引起,采用弹性全过程分析方法会过高估计结构稳定承载力,建议在计算三心圆柱面双层网壳结构的稳定性时采用弹塑性全过程分析方法。     

空间网格结构振型分解反应谱分析合理振型数研究

以钢管桁架、平板网架、双层球面网壳及双层柱面网壳等常用空间网格结构为研究对象,采用振型分解反应谱法进行地震反应分析,分别按《空间网格结构技术规程》及振型质量参与系数累积达到90%确定参与组合的振型数量,通过对所得网格结构杆件动应力相对误差的比较,确定采用振型分解反应谱法进行空间网格结构地震反应分析时所需参与组合的合理振型数量.     

后张拉整体成型局部双层柱面网壳成型过程的研究

局部双层柱面网壳可以通过后张拉闭合平板网架中预留缝隙的方法张拉而成。提出一种可用于张拉成型局部双层柱面网壳的平板理论模型,给出预测成型形状的理论公式。利用ANSYS 10.0有限元计算程序,通过不同节点连接方式模型的对比分析给出最适合张拉的理想模型。     

网架结构安装应力的影响机理

为研究网架结构杆件安装应力的分布特征,对跨度为4、5、6 m各3个,共9个网架模型进行了安装应力试验测量。为说明安装应力对网架极限承载力的影响,对跨度6 m的试验模型进行了极限承载力试验,并将结果与基于理想弹塑性、马歇尔压杆模型的Abaqus非线性分析结果进行了对比。安装应力测量结果表明：少数杆件安装应力接近甚至超过稳定应力。承载力对比表明：试验承载力比理论承载力下降了17.9%,结构安全储备仅为1.25。安装应力通过破坏结构原有对称性、产生杆件初弯曲、促使压杆提前失稳等方式影响网架结构性能,危害网架结构的安全。网架设计特别是满应力设计应当充分考虑安装应力的不利影响。     

新型隔震支座在网壳结构振动控制中的应用研究

将形状记忆合金(SM A)与普通叠层橡胶垫复合可以形成一种新型SM A-橡胶隔震支座.本文阐明了SM A-橡胶支座的工作机理,并建立了支座的理论模型.将设计的新型支座应用于空间网壳结构地震的被动控制,推导了支座隔震空间网壳结构的振动方程.最后,通过某双层柱面网壳结构地震响应的数值模拟考察了SM A-橡胶支座对网壳结构的减振效果.研究结果表明,新型SM A-橡胶支座较普通橡胶支座具有更好的隔震性能,可有效应用于网壳结构的振动控制.     

板锥网壳结构的承载能力分析

板锥网壳结构是一种受力性能合理,技术经济效益良好的新型空间结构形式。本文考虑板片和杆件协同工作时的几何非线性,采用弧长法跟踪荷载—位移全过程平衡路径,对板锥网壳结构的极限承载力性能进行全过程非线性跟踪分析,确定其稳定性能及杆件和锥体单元板件屈服顺序,对板锥网壳结构的破坏机理和极限承载力等问题进行了研究,并与普通双层网壳结构进行了比较,得出了可应用于工程实践的重要结论。     

Research on stability of single-layer inverted catenary cylindrical reticulated shells

The structural configuration and method of analysis of the single-layer inverted catenary cylindrical reticulated shell are introduced in this paper, and the elastic as well as elastic–plastic stability of this kind of reticulated shell is then investigated. The stability of the structures with different types of grid patterns is compared, and the reasonable grid pattern is hence recommended. The structural buckling mode and ultimate load-carrying capacity are studied in detail by parametric analysis. Influence of various factors on structural ultimate load is investigated, and the fitting formula of ultimate load is thus presented. Comparison analysis between the inverted catenary and circular cylindrical reticulated shells is also carried out. The work will provide guidance in theory for practical applications of this kind of structure.     

我国空间钢结构发展中的新技术、新结构

本文阐述了我国空间钢结构——空间网格结构发展应用中的基本情况.文中重点评述了空间网格结构发展与开拓中一些新技术、新结构,诸如大跨度、大面积网格结构、组合网架、组合网壳、三层网架结构、局部双层(单层)网壳结构、预应力网格结构、斜拉网格结构、特种网格结构、新型节点、理论研究与应用研究等等,最后本文展望了21世纪的空间钢结构.     

弯剪共同作用下不锈钢薄腹梁承载性能试验研究

为研究不锈钢薄腹梁在弯矩和剪力共同作用下的承载性能,进行了6根焊接工字形截面不锈钢梁的试验研究。结果表明,所有梁试件的破坏形态为结合了腹板剪切屈曲和受压区板件局部鼓曲的弯剪联合屈曲。建立精细有限元数值模型对试验过程进行模拟,同时考虑了不锈钢材料、几何双非线性,局部几何初始缺陷和焊接残余应力的影响。基于得出的试验和有限元分析结果,对我国《钢结构设计标准》(GB 50017—2017)中考虑腹板屈曲后强度的梁弯剪相关计算方法进行评估。分析表明：当梁的极限承载力受剪切控制时,腹板正则化宽厚比较大时的规范计算承载力偏于保守,而正则化宽厚比较小时的计算承载力与试验和有限元分析结果较为接近;当梁的极限承载力由弯剪共同作用控制时,规范中公式的承载力计算值偏于安全。总体而言,GB 50017—2017的计算方法可以直接应用于计算不锈钢焊接截面梁在弯剪共同作用下的极限承载力。     

Seismic performance assessment of new dry‐assembled prefabricated composite shear wall system with beam‐only connection

Two types of prefabricated composite shear wall systems were proposed using modular and separated dry‐assembled ways, respectively. The seismic performance of four composite shear wall systems, two for the modular assembly way and two for the separated assembly way, was numerically evaluated including failure mode, loading and deformation capacities, hysteresis behavior, ductility, stiffness degradation, and energy dissipation. The nonlinear numerical simulations were conducted based on plastic‐damage constitutive laws for both concrete and steel materials using ABAQUS platform, which were further verified by the experimental investigations. The results showed that the mechanical performance of the modular assembly system is superior than that of the separated assembly system. The former exhibited good bearing and deformation capacities: The peak force is enhanced by 50% on average, the ultimate drift ratio reaches an average value of 3.7%, and the ductility coefficient has an average value of 10.5. As for the same assembly way, the prefabricated system with inner steel plate appeared better seismic properties compared to that with outer steel plate. Furthermore, the modular assembly system behaved prominent energy dissipation capacity with plentiful hysteresis loops. The equivalent damping ratio of this system reaches 15.93% at the drift ratio of 2%, which is the limit drift ratio for normal buildings in rare earthquakes.     

Tragverhalten axial belasteter Stutzen in Kreiszylinderschalen unter Berücksichtigung geometrischer und werkstofflicher Nichtlinearitäten

Axially loaded nozzles in circular cylindrical shells with geometric and physical nonlinearity. The load‐displacement‐relations and the ultimate loads of axially loaded nozzles in circular cylindrical shells are determined by FE‐analyses. These investigations take into account the bi‐linear stress strain behaviour of structural steels and large displacements and instabilities as well. The results which apply for 400 < R/t < 5000 and take into account steel grades up to S690 are presented in graphical form. It is assumed that the thickness t_r of the nozzle is not less than the thickness t of the cylindrical shell. A design rule is given for optimizing the dimensions of pads and insert plates with regard to the effect of the axial load on the nozzle.     

Application and development of modern long-span space structures in China

Modern long-span space structures, developed during the 1970s and 1980s, are light and effective structures based on new technologies and light-weight high-strength materials, such as membranes and steel cables. These structures include air-supported membrane structures, cable-membrane structures, cable truss structures, beam string structures, suspen-domes, cable domes, composite structures of cable dome and single-layer lattice shell, Tensairity structures and so forth. For the premodern space structures widely used since the mid-twentieth century (such as thin shells, space trusses, lattice shells and ordinary cable structures), new space structures have been developed by the combination of different structural forms and materials. The application of prestressing technology and the innovation of structural concepts and configurations are also associated with modern space structures, including composite space trusses, open-web grid structures, polyhedron space frame structures, partial double-layer lattice shells, cable-stayed grid structures, tree-type structures, prestressed segmental steel structures and so forth. This paper provides a review of the structural characteristics and practical applications in China of modern rigid space structures, modern flexible space structures and modern rigid-flexible combined space structures.     

冷弯薄壁钢柱在一致升温情况下的失效分析

采用ANSYS软件对在一致升温情况下的冷弯薄壁短柱进行有限元数值模拟分析。分析结果表明:随着温度的升高,理想短柱的极限承载力的退化速度高于材料极限强度的下降速度,低于钢材弹性模量高温软化速度。研究表明:柱截面的宽厚比影响柱在高温下的极限承载力退化速度;长细比对柱影响较小。通过对比初始局部缺陷柱与理想柱的极限承载力,得到了升温过程中具有初始局部缺陷柱相对于理想轴压柱的极限承载力修正系数曲线。对于求出的柱高温下极限承载力退化系数曲线,给出了冷弯薄壁短柱抗火设计和验算方法。     

Vibration correlation technique for the estimation of real boundary conditions and buckling load of unstiffened plates and cylindrical shells

Nondestructive experimental methods to calculate the buckling load of imperfection sensitive thin-walled structures are one of the most important techniques for the validation of new structures and numerical models of large scale aerospace structures. Vibration correlation technique (VCT) allows determining equivalent boundary conditions and buckling load for several types of structures without reaching the instability point. VCT is already widely used for beam structures, but the technique is still under development for thin-walled plates and shells. This paper intends to explain the capabilities and current limitations of this technique applied to two types of structures under buckling conditions: flat plates and cylindrical shells prone to buckling. Experimental results for a flat plate and a cylindrical shell are presented together with reliable finite element models for both cases. Preliminary results showed that the VCT can be used to determine the realistic boundary conditions of a given test setup, providing valuable data for the estimation of the buckling load by finite element models. Also numerical results herein presented show that VCT can be used as a nondestructive tool to estimate the buckling load of unstiffened cylindrical shells. Experimental tests are currently under development to further validate the approach proposed herein.