Slenderness classification of unstiffened metal plates under shear loading

Buckling behavior of slender and compact carbon steel, stainless steel and aluminum plates under the action of in-plane shear is investigated. Unstiffened shear plates with respect to their slenderness parameter and buckling behavior are qualitatively and quantitatively divided into slender, moderate and stocky categories. Accordingly, slender plates have a low buckling capacity, followed by a large postbuckling reserve. Their ultimate load coincides with the formation of inclined yield bands. Stocky plates yield before buckling. They have some post-yield capacity, buckle plastically and their ultimate and critical loads are equivalent. Moderate plates have concurrent material yielding and geometrical buckling followed by a sudden loss of stiffness. They neither have post-yield nor postbuckling reserves. Since the proportional limit stress is observed to be the cause of bifurcation in stocky plates, it is suggested that in dealing with the slenderness parameter, the yield stress be replaced by the proportional limit stress.     

Inelastic buckling behavior of stocky plates under interactive shear and in-plane bending

Inelastic buckling and postbuckling behavior of stocky plates under combined shear and in-plane bending stresses are investigated and compared to slender plates. Aluminum and steel plates having various slenderness ratios are modeled and analyzed by means of (i) numerical nonlinear finite element method and (ii) theoretical p-Ritz energy method; and both results are compared to the classic interaction equation. It is observed that whereas in slender plates, elastic buckling occurs prior to the material's proportional limit load, stocky plates buckle in an inelastic way within the post-yield stage. In contrast to slender plates with considerable postbuckling reserves, the buckling of stocky plates is immediately followed by softening. In addition, it is shown that the classic interaction equation overestimates buckling loads; and therefore, a modified equation that can safely be applied to both stocky and slender plates is proposed.     

Influence of central cracks on buckling and post-buckling behaviour of shear panels

It is generally accepted that cracks degrade the load bearing capacity of thin plates. The aim of the present paper is to investigate the influence of central cracks on the residual strength and stiffness degradation of shear panels using numerical finite element analysis. Various geometrical and mechanical characteristics of cracked panels such as the crack length, crack angle of inclination, panel aspect ratio, slenderness of panel, boundary conditions, Poisson's ratio, and Young's modulus are considered in the analyses. It is shown that the length and the angle of cracks may change the buckling behaviour of shear panels, and their combinational effects can result in substantial degradation.     

Discrete singular convolution method for buckling analysis of rectangular Mindlin plates

The discrete singular convolution (DSC) method is proposed for solving the elastic buckling problem of thick rectangular plates under a uniaxial compressive loading. To allow for the effect of transverse shear deformation in thick plates, the Mindlin plate theory has been adopted. The numerical results are checked against available analytical and other numerical solutions. It is found that the convergence of the DSC approach is very good and the results agree well with those obtained by other researchers.     

Buckling and postbuckling behavior of unstiffened slender curved plates under uniform shear

Buckling and postbuckling behavior of curved plates under in-plane shear are investigated. After revisiting classic elastic buckling results, the elastoplastic postbuckling behavior and the effects of curvature parameter and aspect ratio are simulated via geometrical and material nonlinear analyses. Imperfection sensitivity is studied for various imperfection shapes and magnitudes. An increase in curvature parameter raises the elastic buckling load, produces unstable buckling and reduces postbuckling reserves. The buckling load and shear capacity are higher in shorter plates. Small initial imperfections are found to have severe effects on the initial buckling load of plates with large curvature parameter, but little effect on ultimate postbuckling capacity.     

Linear and non-linear behaviour of steel plates with circular and rectangular holes under shear loading

In this work, linear buckling and the non-linear behaviour of steel plates with one perforation subjected to shear loading was studied. The influence of the dimension, position with respect to the two main axes, shape (circular or rectangular) and orientation of a hole with respect to the panel slenderness and aspect ratio were all investigated.In both circular and rectangular holes, the strong influence of hole dimensions on the shear buckling coefficient was observed, and the values of the shear buckling coefficient fell with the plate aspect ratio. Small differences in buckling coefficients were noted in rectangular plates with various hole diameters, and buckling coefficients were practically not influenced by the orientation of the rectangular hole. In both rectangular and circular holes, the coefficient remained constant, regardless of hole position for a given distance from the edge.Linear buckling and non-linear behaviour were compared by observing different shear failure modes for slender and thick perforated plates. Elastic and plastic regions were found, on the basis of critical slenderness, for some common geometries.     

小跨高比钢板-混凝土组合连梁抗震性能试验研究

通过7个小跨高比钢板 混凝土组合连梁试件的拟静力试验,研究了连梁跨高比、钢板配钢率以及楼板等因素对其抗震性能的影响,分析了连梁的破坏过程、破坏形态、承载能力、变形能力和耗能能力等。结果表明：相比于不考虑楼板小跨高比PRC连梁,考虑楼板小跨高比PRC连梁增大了连梁的开裂位移,显著提高了连梁的受剪承载力和耗能能力,考虑楼板连梁试件相比于不考虑楼板连梁试件受剪承载力提高了18.03%,破坏时对应的累积耗能是后者的1.66倍;连梁钢板的破坏包括梁墙交界区钢板的开裂和钢板的局部屈曲,钢板的局部屈曲可分为钢板边缘发生的受压局部屈曲和钢腹板的剪切局部屈曲;小跨高比PRC连梁试件的剪压比实测值为0.20~0.30,相应的剪压比设计值为0.39~0.59,内嵌钢板显著提高了小跨高比连梁的剪压比限值。     

波形钢板剪力墙抗震性能试验研究

为研究波形钢板剪力墙在水平荷载作用下的抗侧力性能,完成了水平波形和竖向波形的钢板剪力墙模型的低周往复加载试验,并采用ABAQUS有限元软件对波形钢板剪力墙模型进行了模拟分析。试验结果表明：波形钢板剪力墙结构具有较高的侧向承载力、较强的抗剪屈曲能力和稳定的滞回性能;竖向波形钢板剪力墙在加载过程中发生了沿墙体对角线的X形剪切破坏;水平波形钢板剪力墙在加载过程中未出现波形钢板的屈曲破坏。因此,水平波形钢板剪力墙的极限荷载比竖向波形钢板剪力墙的更高、延性更好、滞回曲线更加饱满。在水平受剪时,竖向波形钢板剪力墙易产生拉压效应,水平波形钢板剪力墙易发生H型钢柱屈曲。波形钢板与边缘约束H型钢柱之间的焊缝未出现开裂,焊缝连接保证结构的整体性能。对比有限元分析结果与试验得到的数据,水平波形钢板剪力墙的荷载、位移比竖向波形钢板剪力墙的更接近试验值。采用有限元法对不同波角和钢板厚度的水平波形钢板剪力墙的抗侧性能进行了分析,结果表明：当钢板比较薄的时候,容易发生波形钢板的剪切破坏;当钢板较厚的时候,容易发生边缘约束H型钢柱的过早屈曲,对结构的承载力和延性不利;当波形钢板的波角为45°时,波形钢板剪力墙的承载力以及延性性能最佳。波角过大或过小时,剪力墙承载力均有所降低。因此,水平波形钢板剪力墙宜采用45°波角与厚度适中的钢板。     

运用MFD方法对以屈曲为破坏标准的叠层复合板进行最优化设计

对给定平面内静力荷载作用下,以屈曲为破坏机制的简支叠层复合板进行最优化设计。目标函数是使得叠层板的屈曲荷载达到最大,纤维方向为设计变量。有限元分析中应用了一阶剪切变形理论。优化设计中考虑了弯扭力偶的作用,同时采用了以Matlab和Golden Section法编制的计算机程序进行计算。对宽厚比、纵横比、层数、各向异性材料、荷载比(Ny/Nx)等材料特性中其他一些不确定因素进行了对比和分析。     

十字加劲钢板剪力墙的抗剪极限承载力

我国《高层民用建筑钢结构技术规程》规定了钢板墙剪切弹性屈曲不先于剪切屈服,其明显的不足是没有利用板的屈曲后强度,同时弹性屈曲也不能作为结构在弹塑性阶段的设计指标。本文应用板的大挠度弹塑性有限元方法对十字加劲方形钢板剪力墙的屈曲后性能和极限承载力进行了系统的研究,并在大量数值分析的基础上,提出了以板的平均剪切应变相应的剪应力作为钢板剪力墙承载能力的极限状态,以达到利用薄板屈曲后强度的目的,进而提出了钢板剪力墙承载力的设计简化计算公式及钢板墙侧柱刚度阈值的计算公式,供设计参考。数值计算结果表明,影响钢板墙抗剪性能主要有三个参数:板高厚比、肋板刚度比和边柱刚度。     

双钢板-混凝土组合剪力墙抗震性能试验研究

提出一种新型的配置L形拉结件的双钢板-混凝土组合剪力墙。通过两组共6个双钢板-混凝土组合剪力墙试件的拟静力试验,对此新型组合剪力墙的抗震性能进行了研究。试件改变参数主要为轴压比和连接件间距,在试验的基础上对试件的破坏形态、承载能力、滞回曲线、骨架曲线、刚度退化曲线等进行分析。试验研究表明：L形拉结件的配置既能增强外包钢板对核心内混凝土的约束作用又能抑制外包钢板的屈曲,充分保证了外包钢板和混凝土之间的协同工作,此新型组合剪力墙具有较高的承载力,较好的延性及耗能能力。在达到峰值荷载之前,墙体钢板未发生明显的局部屈曲变形,最终组合剪力墙均因端柱屈曲拉裂而开始破坏;破坏时极限位移角的平均值为1/58;随着距厚比减小,试件的水平承载力和延性系数均显著提高。     

波纹钢板剪力墙抗震性能试验研究

提出一种新型钢板墙-波纹钢板剪力墙。设计了两个不同形式的波纹钢板剪力墙试件,采用低周往复加载试验,分析二者的破坏形式,对滞回曲线、骨架曲线、延性、刚度及耗能性能等性能进行了系统的研究。研究表明：两种波纹钢板剪力墙均具有较高的极限承载力及初始刚度;屈曲承载力较高,屈服位移较小,能够较快地进入塑性耗能;滞回曲线较为饱满,不易发生捏缩现象。与横向波纹钢板剪力墙相比,竖向波纹钢板剪力墙的滞回性能及屈服后承载力更加出色。结果表明,在合理的参数设计下,所提出的波纹钢板剪力墙承载力高、耗能性能较强,是一种极具前景的新型抗侧力构件及耗能构件。     

Theoretical elastoplastic buckling of stringer stiffened cylindrical shells

A linear analysis method is offered to predict the theoretical elastoplastic buckling of stringer stiffened cylindrical shells subjected to longitudinal loading. Welding residual stresses are taken into account in the calculation, but effects of geometrical imperfections and pre-buckling displacements are ignored.The examples analysed show a good correlation between the analytical results and those obtained experimentally with stocky models of moderate geometrical imperfections.     

剪切型防屈曲钢板阻尼器的滞回性能试验研究

剪切型钢板阻尼器广泛应用于建筑结构的抗震设计中,但现有的钢剪切板阻尼器腹板易发生平面外屈曲,从而引起耗能腹板的疲劳破坏。为此,提出了剪切型防屈曲钢板阻尼器,是在传统的钢板阻尼器的基础上,在腹板的两侧增加了约束板和固定板,约束板用于防止耗能腹板的屈曲变形,固定板为约束板提供支撑。为研究剪切型防屈曲钢板阻尼器的滞回性能,设计了3个试件并对其进行了拟静力试验。试验结果表明：剪切型防屈曲钢板阻尼器可以有效抑制耗能腹板平面外屈曲,与传统钢板阻尼器相比,具有较强的耗能能力;约束板合理的形状对剪切型防屈曲钢板阻尼器性能有较大影响。采用数值模拟方法对剪切型防屈曲钢板阻尼器进行参数分析,研究了宽厚比对阻尼器滞回性能的影响。结果表明腹板宽厚比取值过大或过小时,承载力和耗能性能降低,但等效黏滞阻尼系数增大。     

Experimental Study on Low Cyclic Loading Tests of Steel Plate Shear Walls with Multilayer Slits

A new type of earthquake-resisting element that consists of a steel plate shear wall with slits is introduced. The infill steel plate is divided into a series of vertical flexural links with vertical links. The steel plate shear walls absorb energy by means of in-plane bending deformation of the flexural links and the energy dissipation capacity of the plastic hinges formed at both ends of the flexural links when under lateral loads. In this paper, finite element analysis and experimental studies at low cyclic loadings were conducted on specimens with steel plate shear walls with multilayer slits. The effects caused by varied slit pattern in terms of slit design parameters on lateral stiffness, ultimate bearing capacity and hysteretic behavior of the shear walls were analyzed. Results showed that the failure mode of steel plate shear walls with a single-layer slit was more likely to be out-of-plane buckling of the flexural links. As a result, the lateral stiffness and the ultimate bearing capacity were relatively lower when the precondition of the total height of the vertical slits remained the same. Differently, the failure mode of steel plate shear walls with multilayer slits was prone to global buckling of the infill steel plates; more obvious tensile fields provided evidence to the fact of higher lateral stiffness and excellent ultimate bearing capacity. It was also concluded that multilayer specimens exhibited better energy dissipation capacity compared with single-layer plate shear walls.     

考虑板件局部失稳影响的钢框架极限承载力分析

在精炼塑性铰梁单元模型的基础上,采用弯曲切线和轴向切线模量两套体系考虑板件局部失稳对钢框架结构极限承载力分析的影响,通过试验证明了这种方法的准确性和有效性。     

高轴压比下中高剪跨比双钢板-混凝土组合剪力墙抗震性能试验研究

通过对4片高轴压比、中高剪跨比双钢板-混凝土组合剪力墙的拟静力试验,研究该类组合剪力墙在低周往复水平荷载作用下的受力性能和破坏模式,分析其延性、刚度、承载力、耗能等性能指标,以及剪跨比、轴压比、距厚比（栓钉间距与钢板厚度之比）等因素对其抗震性能的影响。试验结果表明：中高剪跨比试件的破坏模式为压弯破坏;墙体钢板随距厚比的增加更易发生局部屈曲;试件轴压比越大,压屈越明显、屈曲范围越接近试件底部、屈曲发展越迅速;试件刚度和极限荷载受轴压比、距厚比的影响较小,但变形能力随轴压比的增大而降低;试件剪跨比越大、轴压比越小,滞回性能越稳定;试件耗能随变形增大而迅速增长,抗震性能良好。     

Finite element analysis of local buckling behavior of steel plates in concrete-filled double steel plate composite shear walls

采用ABAQUS有限元软件对双钢板-混凝土组合剪力墙中外包钢板的局部屈曲行为进行了有限元模拟,分析外包钢板在轴压作用下的局部屈曲和屈曲后的受力性能。共开展了15个模型的有限元分析,模型的变化参数包括钢板的宽厚比和对拉钢筋的列数。分析结果表明：对于列间距和行间距相同的对拉钢筋布置方案,钢板局部屈曲始终发生在相邻两对拉钢筋之间;钢板发生屈曲后,与屈曲位置相邻的对拉钢筋承受较大的拉力,且对拉钢筋拉力随着对拉钢筋间距的减小而增大;增加对拉钢筋列数和减小钢板宽厚比可有效改善外包钢板的局部稳定性能,提高钢板的承载能力和变形能力;相比点约束,线约束对钢板局部屈曲的约束更为有效;无对拉钢筋模型、单列对拉钢筋模型和双列对拉钢筋模型达到屈服强度（345MPa）所需的最小宽厚比分别为25、30和37.5。     

新一代土层地震反应分析方法

剖析了当今国际上频域等效线性化和时域非线性求解土层地震反应分析方法的典型代表SHAKE2000与DEEPSOIL,对目前其他学者FDM改进方式的可行性进行评判,采用新的直频法动剪模量阻尼比求解技术,提出新一代一维土层地震反应计算方法和程序SOILQUAKE,并用四种类别和巨厚场地实际记录检验了新程序。结果表明：SHAKE2000与DEEPSOIL在一类、二类场地上基本一致且结果可靠,三类和四类场地上两程序计算反应谱“矮粗胖”现象严重,与实际情况相差甚远;现有考虑频率相关性的FDM改进方式,其基本出发点存在定性错误;对硬场地和中硬场地,SOILQUAKE与SHAKE2000和DEEPSOIL结果大致相似,但在高频部分表现比SHAKE2000更加合理,与DEEPSOIL基本一致;对软场地和巨厚场地,SOILQUAKE克服了SHAKE2000和DEEPSOIL严重低估场地放大效应的缺点,模拟结果与实测记录较为接近,在软场地上优势显著,在巨厚软场地上优势十分显著。SOILQUAKE首先攻克现有软土层地震动计算结果“矮粗胖”和硬土中等效线性化方法缺少高频分量求解难点,具备了作为新一代一维土层地震反应计算方法的能力,将在http://www.soilquake.com或http://www.soilquake.cn上提供共享服务。