新型桥面板结构稳定性能研究

分别建立了正交异性普通钢桥面板和正交异性钢-聚氨酯夹层桥面板的有限元模型,并另外建立了不同U型肋数量和不同面层钢板厚度的夹层板计算模型,在边界条件、加载情况均相同的条件下进行有限元模拟分析,夹层板采用板-实体-板结构模拟,结果表明:在相同条件下,夹层板比普通钢板屈曲临界应力、刚度、强度均有较大程度的提高,U型肋间距、面层钢板厚度对夹层板的屈曲临界应力及屈曲破坏形态有较大影响,两种因素分别超出一定范围后,对板整体的影响又受到相互制约。     

钢-聚氨酯夹层桥面板抗弯性能参数分析

为探讨钢-聚氨酯夹层板的弯曲基本性能,本文采用数值计算的方法,通过模拟四边简支夹层板受垂直板面的局部均布力作用,分析了钢面板厚度、芯层厚度和芯层弹性模量三个参数变化对该种夹层板的应力状况和抗弯性能的影响。得出钢面板厚度和芯层厚度能有效降低钢面板的弯曲应力水平,提高板的抗弯刚度,而芯层弹性模量对夹层板的抗弯性能则基本无影响。     

不锈钢芯板结构L形柱轴压性能有限元分析

不锈钢芯板结构L形柱是充分利用夹层结构和不锈钢的优点提出的一种新型异形柱结构形式。为研究不同面板厚度、芯管厚度以及芯管间距对不锈钢夹层结构L形柱稳定承载力的影响,分析其破坏形态和屈曲模式,利用有限元软件ABAQUS建立有限元分析模型并对其做轴压荷载下的模拟,分别进行特征值屈曲分析和非线性屈曲分析,通过对单一参数变化条件下柱的屈曲模式、变形以及荷载-位移曲线等方面的分析,全面研究这种新型L形柱轴压构件的性能。研究表明:该L形柱的屈曲模式表现为弯曲屈曲,其破坏形态为局部屈曲破坏,随着面板厚度的增加,芯管对面板的约束越来越弱,对其稳定承载力的贡献越来越小,同时发现芯管厚度和芯管间距对其稳定承载力的影响很大。     

钢板夹钢管组合板弯曲变形与最大承载力

对3块钢板夹钢管组合板进行了抗弯试验,绘制了荷载–位移(P-δ)曲线,记录了加载失效过程图。基于假设的失效模型和能量原理,推导建立了组合板最大承载力公式,并将最大承载力理论值与试验值进行比较。对试验结果进行了模拟与验证,讨论了钢板厚度和钢管壁厚对最大承载力的影响,并将最大承载力理论值与模拟值进行对比分析。结果表明:钢管数量越多,承载力越大。变形失效时,主要有焊缝开裂、上钢板局部屈曲和芯层钢管局部压扁等现象。数值模拟可以较好地预测试验最大承载力和变形情况。推导的最大承载力公式可以较好地预测试验结果和模拟结果,具有较高的精度。当用钢量增加较少时,仅增加上钢板厚度对提升组合板最大承载力最为有效。当用钢量增加较多时,同时增加上下钢板厚度对提升组合板最大承载力最为有效。     

火灾下防屈曲支撑最小填充层厚度简化计算方法

为防止火灾下防屈曲支撑的抗震性能降低,需确保在给定的耐火时间内,防屈曲支撑的芯材温度不高于临界温度和防屈曲支撑的弯曲刚度不低于最小需求刚度。通过增加防屈曲支撑填充层厚度,一方面可以降低火灾下支撑芯材的温度,另一方面可以增加火灾下防屈曲支撑的刚度。通过对芯材截面形状为十字形的防屈曲支撑火灾升温的有限元分析,研究了填充层厚度对支撑芯材温度和火灾下支撑刚度的影响。随着填充层厚度的增大,芯材温度降低,支撑刚度增大。根据火灾下防屈曲支撑强度和刚度均不降低的条件,给出了填充层最小厚度和防屈曲支撑套管最小尺寸的简化计算方法,并通过算例介绍了防屈曲支撑的抗火设计方法。     

轻钢复合夹芯板墙构造及抗震性能研究

针对低层轻钢结构住宅房屋,提出了一种新的夹芯复合板墙形式,夹芯墙内外层分别采用50 mm厚的火山渣混凝土,内外墙设置钢筋网,中层保温板采用150 mm厚的挤塑聚苯乙烯板(XPS),设置钢桁架与钢腹杆提高整体性;设计了复合板墙板与板之间的水平缝、垂直缝与阳角缝连接形式,采用预埋件与焊接在钢梁上的角钢螺栓连接形式将夹芯板墙固定于钢框架上;对夹芯板墙与钢框架进行有限元模拟抗震性能运算,研究了夹芯板墙与钢框架在单螺栓连接与双螺栓连接方式下的破坏机理。     

U形钢板-混凝土高强螺栓连接组合空腹夹层板楼盖结构研究与应用

提出一种多层大跨度结构体系--U形钢板 混凝土高强螺栓连接组合空腹夹层板楼盖,该结构体系由U形钢板-混凝土组合下肋、钢筋混凝土上肋和上下肋间设置的钢筋混凝土剪力键形成的需考虑夹芯层剪切变形的空间楼盖。介绍了该楼盖结构体系的简化计算模型、弹性连续化理论分析方法和实用分析方法,通过仿真模型试验及实际工程应用,验证了弹性连续化理论分析方法与实用分析方法的正确性。研究结果表明：采用由上、下表层薄膜刚度和具有一定抗剪刚度的剪力键夹芯层组成的U形钢板-混凝土高强螺栓连接组合空腹夹层板楼盖简化计算模型进行弹性连续化理论分析,其分析结果与仿真模型试验结果基本相符,相对误差最大不超过5%;按等强和等刚度原则将U形钢板-混凝土组合空腹夹层板折算成钢筋混凝土实腹梁的实用分析方法,其计算结果与仿真模型试验结果基本相符,相对误差最大不超过4%。以黑龙江中医药大学文体中心B区57 m×39 m+57 m×36 m双跨多层（地下1层、地上3层）工程为算例,并与原位测试结果进行比较,说明U形钢板-混凝土高强螺栓连接组合空腹夹层板楼盖安全可靠,且具有较好的经济性。     

组合钢板剪力墙受剪性能分析

改进型组合钢板剪力墙(I-CSPW)和防屈曲钢板剪力墙(BR-CSPW)均由边缘框架、钢板和与钢板用螺栓连接的混凝土板构成,但BR-CSPW在混凝土板上预留了比螺杆直径大的孔。进行了两种组合钢板剪力墙的低周反复加载试验,研究了I-CSPW和BR-CSPW在水平往复荷载作用下的破坏模式、承载力、抗侧刚度、耗能能力和延性。利用ABAQUS软件建立有限元模型,通过变化钢板和混凝土板的厚度,考察两种组合剪力墙在水平荷载作用下的承载力、抗侧刚度及混凝土损伤的差异。结果表明,随着钢板厚度增大,I-CSPW的混凝土板损伤发生时间提早,损伤程度增大。相反,钢板厚度的增大却能延迟BR-CSPW的混凝土板破坏。为抑制钢板屈曲,BR-CSPW所需的混凝土板厚度较I-CSPW小。     

钢蒙皮-复合材料芯材夹层板弯曲性能研究

采用钢板蒙皮与玻璃纤维增强复合材料(GFRP)拉挤成型的空心方管芯材组成夹层结构,运用四点弯曲试验方法,开展了钢蒙皮-复合材料芯材夹层梁的受弯性能试验,研究了其受力性能情况、跨中上下面板应力分布和跨中挠度。运用换算截面法推导出钢蒙皮-复合材料芯材夹层板截面有效抗弯刚度,并采用材料力学理论推导出夹层板跨中挠度计算公式,计算各试件的跨中上下面板应力分布情况和跨中挠度。研究结果表明:当芯材厚度一致时,试件的跨中挠度随着钢板面层厚度的增加而逐渐减小;跨中挠度理论值与试验值吻合较好。     

单面外包混凝土组合钢板剪力墙的混凝土板厚需求

外包混凝土组合钢板剪力墙抗剪承载力高、抗侧刚度大、耗能能力强,是一种有效的高层结构抗侧力构件。该构件利用钢筋混凝土板对钢板提供的侧向约束,使得钢墙板屈曲晚于剪切屈服。延性设计要求钢板进入剪切屈服后要有一定的变形耗能能力,混凝土板需达到一定的厚度才能保证钢板发生弹塑性屈曲。因此混凝土板厚需求是组合钢板剪力墙设计中的一个关键问题,但前人对于这方面的研究并不是很多。考虑栓钉间距、混凝土板厚度、钢板厚度、混凝土强度等级、墙板高宽比的变化对单面外包混凝土组合钢板剪力墙进行了弹塑性分析。基于有限元计算结果,提出了单面外包混凝土组合钢板剪力墙在层间侧移角小于0.4%时钢板不发生屈曲的混凝土板厚需求计算公式。     

Finite element analysis and design of sandwich panels subject to local buckling effects

Past research into the local buckling behaviour of fully profiled sandwich panels has been based on polyurethane foams and thicker lower grade steels. The Australian sandwich panels use polystyrene foam and thinner and high strength steels, which are bonded together using separate adhesives. Therefore a research project on Australian sandwich panels was undertaken using experimental and finite element analyses. The experimental study on 50 foam-supported steel plate elements and associated finite element analyses produced a large database for sandwich panels subject to local buckling effects, but revealed the inadequacy of conventional effective width formulae for panels with slender plates. It confirmed that these design rules could not be extended to slender plates in their present form. In this research, experimental and numerical results were used to improve the design rules. This paper presents the details of experimental and finite element analyses, their results and the improved design rules.     

夹芯板弯曲屈曲分析的有限条-棱方法

用有限条 -棱方法对冷弯薄壁型钢压型表面泡沫夹芯板进行了弯曲屈曲分析 ,得到了夹芯板受压面层屈曲时的临界应力、屈曲荷载及屈曲半波长 ,并与试验结果进行对比 ,理论值与试验值吻合较好     

Shear buckling in foam-filled web core sandwich panels using a Pasternak foundation model

Web core panels, foam-filled sandwich panels with interior webs, are a structurally efficient option for transverse load bearing applications. In web core panels, the interaction between the webs and core material can have a substantial impact on web shear buckling strength and is a key element of lightweight structural design. The present work is an investigation of web buckling behavior in web core panels under a distributed load. To solve this problem, web shear buckling was analyzed for the case of pure shear loading with foam support, and this analytic model was extended to the case of panels with a transverse distributed load. The webs are modeled as simply supported plates resting on a Pasternak elastic foundation. To that end, a buckling model for plates on a Pasternak foundation is presented, along with closed-form approximations of the solution for square and infinitely long plates. An accurate model for the foundation constants is developed using energy methods. Applicability of the plate buckling model to web core panels with transverse loads is presented via a finite element study. In panels, the slenderness and spacing of the webs have a slight effect on the boundary conditions between the webs and face sheets. The effect is relatively small, however, and the model presented in this work underpredicts buckling strength by less than 25%. The model in this work is thus a reasonable approach to the practical design of web core panels.     

An investigation of lightly profiled sandwich panels subject to local buckling and flexural wrinkling effects

Sandwich panels exhibit various types of failure modes depending on the steel face used. For the flat and lightly profiled sandwich panels, flexural wrinkling is an extremely important design criterion as the behaviour of these panels is governed mainly by flexural wrinkling. However, in the lightly profiled panels, when the depth or spacing of the ribs increases, flat plate buckling between the ribs occurs leading to the failure of the entire panel due to the interaction between local buckling and flexural wrinkling modes. Current design formulae for sandwich panels do not consider such interactive buckling effects. To obtain a safe design solution, this interactive buckling behaviour should be taken into account in the design of lightly profiled sandwich panels. Therefore a research project was undertaken to investigate the interactive buckling behaviour of lightly profiled panels with varying depths and spacings of the ribs using a series of experiments and finite element analyses. A new improved design formula was developed for the safe and economical design of lightly profiled panels that takes into account the interaction between local buckling and flexural wrinkling. This paper presents the details of this investigation, the results and the new design formula.     

An analytical study on post-buckling behaviour of imperfect sandwich panels subjected to uniform thermal stresses

The governing equations for determining thermal buckling of imperfect sandwich plates are developed using the large deflection theory and considering first shear deformation principles. The equations are then solved via an analytical method comprising infinite summation of trigonometric series and defining in-plane and out-of-plane displacement. After verification of the proposed method and convergence studies, the effects of parameters like plate aspect ratio, material properties and layer setting angles on buckling stress and the post-buckling path are studied. Numerical results show that the number of trigonometric terms does not affect the buckling thermal stress or the post-buckling path of sandwich plates having face layer setting angles less than 15°. Results also show that the buckling stress and post-buckling path for complementary layer setting angles are similar and that the rate of variation of bifurcation points for different face layer setting angles of sandwich panels strongly depend on material properties, especially on the face and core stiffness. Furthermore, for aspect ratios greater than five, buckling thermal stress remains about constant.     

Component sizing approach for the sandwich plate system

The sandwich plate system (SPS) is a bridge deck system consisting of steel face plates bonded to a rigid polyurethane core. SPS bridges are typically constructed as a series of pre-fabricated SPS deck panels compositely connected with traditional steel girders. The decks are thin, lightweight and modular, and can be tailored to numerous applications including both new bridge and rehabilitated bridges.

With new system, there exist hurdles in the implementation; for SPS, the primary challenge is the lack of an established design method for the panel cross-sections. Presented herein is a method for sizing SPS panel sections for bridge applications. This method is limited to the selection of steel plate and core dimensions, subjected to American Association of State Highway and Transportation Officials (AASHTO) limit states of serviceability, strength and fatigue and does not consider connections or bond aspects of the system. The sizing approach considers the deck panels as plates with variable boundary conditions subjected to the loading conditions of the AASHTO Load Resistance Factored Design (LRFD) bridge design specification. Results from this study indicate that the component sizing for SPS deck panels is controlled by stiffness and that plates selected to satisfy the AASHTO limiting deflection criterion will also be adequate for the remaining serviceability, strength and fatigue limit states.     

Analysis of thin-walled structures by finite strip and finite layer methods

The finite strip and finite layer methods are powerful tools for the analysis of thin-walled structures. In this paper, the finite strip method is applied to study the behavior of cold-formed steel beams including webs with longitudinal stiffeners. Comparisons are made with AISI specifications and published data. The finite layer method is used to investigate the buckling behavior of sandwich panels with thin facings and rigid foam cores. Effects of variable core stiffnesses (due to uneven curing, etc.) on the buckling strength are quantified and presented.     

Sandwich panels

In recent years, there has been increasing interest in the use of structural sandwich panels as the cladding of buildings and a good deal of research and development has been carried out. This paper reviews the state of the art with regard to the structural design of elements consisting of two thin metal faces separated by a lightweight core. Various aspects are discussed but two are given particular attention, namely methods of global analysis and the local buckling of compressed face elements. The analysis of sandwich panels under all possible loading and boundary conditions no longer poses any problem. Classical solutions, approximate solutions and numerical methods such as finite elements all have their place and are reviewed in detail. Local buckling phenomena in sandwich elements are similar to those in other thin-walled metal elements with the added consideration that buckling is resisted by the core material. This leads to some quite complex analysis which requires simplification for practical design. The paper includes a useful bibliography of recent references.     

Laterally supported sandwich panels subjected to large deflections: Part 2: FE analyses and model validation

Finite element (FE) models are used for predicting the global behavior of simply supported sandwich panels fixed by bolts on the two longitudinal edges or on all their four edges. The panels are subjected to transversal distributed loads and develop large deflections. Two finite element techniques are employed: (a) utilizing effective (equivalent) continuum solid elements for the core and plate elements for the face sheets and (b) utilizing plate elements of an equivalent three-layer laminate. In the first part of this project, discussed in a companion paper, the test set-up details were presented along with the experimental results. This second part of the work presents the procedure for estimating the panel–bolt bearing stiffness, the FE analysis procedure developed to simulate the behavior of the tested panels and the validation of the numerical models. A good correlation was observed between experimental and numerical results for the displacements of the panels and the shear loads at the attachment points. The results obtained demonstrated that the proposed two-dimensional FE approach yields a good trade off between the level of accuracy and computational efficiency.