边缘加劲板在均匀压力下的试验研究

目前,已有许多关于不同边界条件钢板在各种荷载下的试验研究。经典的类型是钢板纵向边缘受约束(加劲)或不受约束(不加劲)。但是现有文献没有关于钢板纵向边缘部分约束(部分加劲)的试验报告。对30块三边简支、单纵边加劲的钢板进行试验分析。试件的边缘加劲从零加劲(自由边)到刚性加劲变化,在此中间状态的边缘加劲就是部分加劲钢板。部分加劲钢板的性能由一套三维照相测量系统进行记录,并讨论了多大尺寸的边缘加劲肋才能提供足够刚性的约束。试验中的边缘加劲板的类型有简单边缘板、简单倾斜边缘板和复杂边缘板。根据数值研究得到关于部分加劲板强度计算的设计准则是准确可靠的,并且证明现有的国际冷轧钢结构规范所采用的一般强度方法有效。     

钢箱梁局部稳定性计算方法研究

由于钢箱梁纵向加劲肋受力比较复杂从而给计算带来不便。为简化计算,文章一方面提出钢箱梁受压部分在有无设置纵肋时的局部屈曲临界应力之差等效为纵肋的临界轴向压力并以此作为腹板在纯弯作用下纵肋局部稳定设计标准;另一方面,以相似截面形状压应力分布相似为基础,利用等效法将闭口和开口加劲肋与主钢板一起分别等效为箱形截面和T形截面;同时,在加劲肋属于全加劲时,不考虑加劲板横向变形的情况下,根据欧拉公式按加劲板惯性矩和宽度相等的原则将之等效为矩形截面钢板。     

槽钢加劲钢板剪力墙受力性能研究

竖向槽钢加劲钢板剪力墙由内嵌钢板、边缘构件和墙板两侧对称布置的竖向槽钢加劲肋组成。槽钢加劲肋具有较高的抗弯、抗扭刚度,可为墙板提供有效的面外约束和轴向支撑作用。利用有限元分析软件ABAQUS对槽钢加劲钢板墙进行屈曲分析和静力弹塑性分析,研究槽钢距边缘构件距离、钢板宽厚比、高厚比、肋板刚度比和柱刚度对钢板墙及边缘构件力学性能的影响。结果表明,槽钢加劲肋至边缘构件的距离主要影响钢板墙的平面外变形,对钢板墙屈曲应力和承载力的影响较小。槽钢加劲肋可以有效提高墙板的屈曲应力。随着宽厚比和高宽比的减小,结构的承载力和刚度均显著提高。增大肋板刚度比可提高钢板墙的初始刚度和屈曲应力,肋板刚度比应大于20。为避免边框柱变形过大或过早破坏,边框柱应具有足够的刚度,增大柱刚度可以提高钢板墙的初始刚度,减缓墙板刚度的退化。     

竖向荷载下加劲钢板剪力墙力学性能研究

对加劲钢板剪力墙试件在有限竖向荷载作用下进行了单向推覆加载试验,进行了力学性能研究,结果表明十字加劲钢板墙有很高的极限承载力和初始抗侧刚度,加劲肋能很好的抑制板的面外位移,竖向加劲肋的受力明显大于水平加劲肋。有限元分析表明,十字加劲肋能有效提高钢板墙的极限承载力和初始抗侧刚度;较小的竖向荷载对钢板墙的受力性能影响不大。     

钢板剪力墙结构竖向防屈曲简化设计方法

采用能量原理推导了设置竖向加劲肋钢板墙的弹性屈曲应力的简化计算公式,并根据理论公式进行了参数分析,研究了钢板高宽比、加劲肋数量、加劲肋与钢板刚度比以及加劲肋与钢板面积比等参数对钢板墙竖向屈曲荷载的影响。简化公式计算结果与有限元计算结果吻合良好。研究表明,在钢板墙高宽比确定的情况下,加劲肋与钢板的刚度比是影响加劲板竖向屈曲荷载的主要因素,加劲肋与钢板的面积比对加劲板屈曲荷载的影响较小,加劲肋端部与周边框架不连接的钢板墙优于加劲肋端部与周边框架连接的钢板墙。     

无粘结十字加劲钢板剪力墙结构抗剪性能分析

十字加劲钢板剪力墙已被试验证明是优秀的抗侧力耗能构件,但加劲构件与内嵌钢板无粘结时,其对内嵌钢板的作用尚需进一步研究。利用有限元分析软件ABAQUS,对单层单跨无粘结十字加劲钢板剪力墙结构的抗剪性能进行数值模拟,分析在水平荷载作用下,构件的受力破坏特征及抗剪性能。研究表明,无粘结十字加劲钢板剪力墙结构具有良好的延性及抗剪性能,内嵌钢板能承担更多的剪力,对周边框架不利作用的降低幅度与传统十字加劲钢板剪力墙基本相同。参数分析结果表明:框架柱轴压比、墙体高厚比和肋板刚度比是影响钢板剪力墙抗剪性能的主要因素。     

稀疏竖向加劲钢板剪力墙性能研究

对考虑竖向荷载作用的稀疏竖向加劲钢板剪力墙试件进行了试验和有限元研究,给出了试件的面内面外位移曲线和等效Mises应力曲线,考察了不同大小的竖向荷载对加劲钢板剪力墙性能的影响.研究表明,稀疏竖向加劲钢板剪力墙有较高的初始抗侧刚度和极限承载力,整体失稳后仍能继续稳定地承受荷载,竖向加劲肋应力在区格屈曲前后变化较大,有限竖向荷载对加劲钢板剪力墙的初始刚度基本没有影响,但会降低剪力墙的极限荷载和极限侧移.     

板肋加劲板整体稳定数值模拟与受力机理研究

分别采用梁单元与板壳单元建立同时考虑初始几何缺陷和焊接残余应力的受压板肋加劲板整体稳定分析有限元模型,并以相应试验结果进行验证,得到梁与板壳单元模拟受压板肋加劲板整体稳定的异同。采用经验证的数值模拟方法,对不同弯曲失稳方向板肋加劲板的受力机理进行了研究。结果表明:采用板壳单元可以较好还原板肋加劲板整体稳定受力性能,板壳有限元模型与试验试件的承载力最大相对误差为4.2%,平均相对误差为1.48%; 梁单元模型与长(中长)柱试验试件的承载力最大相对误差为5.4%,平均相对误差为1.92%,与短柱试件的承载力相对误差虽仅为0.7%,但由于不能考虑板件发生的塑性失稳,其应力-位移曲线拟合情况相对较差; 不同弯曲失稳方向板肋加劲板整体稳定构件的破坏特征不同,其中对于板肋侧弯曲的板肋加劲板整体稳定构件,被加劲板边缘部分受压达到材料屈服强度且板肋边缘受拉达到屈服强度时,构件整体达到其承载极限; 对于被加劲板侧弯曲的板肋加劲板整体稳定构件,当板肋边缘部分受压达到材料屈服强度时,构件整体达到其承载极限; 对于实际工程中组成钢箱梁顶板的板肋加劲板,制作时应避免朝向板肋侧的变形。     

考虑竖向荷载的外包装饰层钢板剪力墙抗震性能试验研究

为研究实际钢结构住宅项目中钢板剪力墙最真实的抗震性能和外包装饰层的变形能力,设计了4榀足尺钢管混凝土框架-竖向加劲钢板剪力墙试验构件,对受竖向荷载作用下的钢板剪力墙试件进行了拟静力试验,对比研究了外包装饰层、竖向加劲肋布置方式对钢板剪力墙结构抗震性能的影响。研究结果表明：在竖向荷载和水平往复荷载共同作用下,钢板剪力墙试件仍具有较高的承载力,优良的耗能性能和延性。钢板剪力墙外包的砌体装饰层可提高钢板剪力墙在地震作用下的初始刚度与耗能能力,但会加快试件达到峰值荷载后承载力的退化,而对钢板剪力墙构件的峰值荷载、延性系数以及刚度退化并无显著影响。竖向加劲肋等距布置的钢板剪力墙峰值承载力略高于不等距布置的试件,而两种加劲肋布置方式对试件其他方面的性能影响较小。在试验和已有文献的基础上,提出了应用于该类贴砌式外包装饰层钢板剪力墙在地震作用下的有害位移角分级方法。     

井字形加劲部分连接钢板剪力墙的性能分析

井字形加劲部分连接钢板剪力墙是对部分连接钢板剪力墙进行了加劲改进,在保持其优势的同时,改善其性能,是一种新型钢板剪力墙结构体系。井字形加劲后,结构的传力机制变得更为复杂,采用有限元软件ABAQUS进行模拟计算,探究了井字形加劲部分连接钢板剪力墙在水平低周往复荷载作用下的滞回性能,分析了加劲位置、肋板高厚比、加劲刚度比和钢板高厚比等相关参数对结构整体性能的影响。     

Experiments of edge-stiffened plates in uniform compression

There is a large body of literature on the experimental behaviour of steel plates under a variety of loading and edge support conditions. Typically the longitudinal plates edges were either laterally restrained (stiffened) or laterally unrestrained (unstiffened). There are no such plate experiments reported in the literature of plates with a longitudinal edge stiffened with an edge-stiffener (partially stiffened). This paper presents 30 plate tests of plates simply supported on three sides, with the remaining (longitudinal) edge stiffened with an edge-stiffener. The edge-stiffener was increased in size from zero (unstiffened plate) to a size sufficient to create a stiffened edge (stiffened plate). Edge-stiffeners of an intermediate size resulted in partially stiffened plates. The behaviour of partially stiffened plates is fully documented with the aid of a 3D photogrammetry system, and the adequate size of edge-stiffeners required in order to create a stiffened plate edge are discussed. Edge-stiffener types investigated are simple lips, simple inclined lips and complex lips. Design procedures for partially stiffened elements previously inferred from numerical studies are shown to accurately and reliably determine the plate strengths, and further validate the procedure for use as a general strength approach in current international cold-formed steel specifications.     

Effect of longitudinal stress gradient on the ultimate strength of thin plates

When thin-walled sections are subjected to a moment gradient, the plates that comprise the section are themselves subjected to a longitudinal stress gradient. This paper analyzes the effect of longitudinal stress gradient on the ultimate strength of thin plates. Two types of thin plates are investigated: (1) plates simply supported on all four edges; and (2) plates simply supported on three edges, and with one longitudinal edge free. These two cases illustrate the influence of longitudinal stress gradient on stiffened and unstiffened elements of cold-formed steel sections, respectively. Nonlinear finite element analysis (ABAQUS) was performed to determine the ultimate strength of thin plates under a longitudinal stress gradient. The results indicate that the longitudinal stress gradient increases the strength of both types of thin plates, but has significantly more influence on unstiffened elements than stiffened elements. The beneficial effect of longitudinal stress gradients can be accounted for in design by using a plate buckling coefficient modified to account for the longitudinal stress gradient, an example of the impact of this change on a common cold-formed steel channel is provided.     

冷弯型钢截面局部屈曲和AISI规范有效宽度计算的统一法则

本文介绍了美国AISI冷弯型钢结构规范关于有效宽度计算的统一法则,并综述了加劲板件、非加劲板件、边缘加劲板件等在各种应力分布状态下的屈曲系数k的计算方法。最后。比较了加劲板件按美国AISI规范和我国规范GB50018有效宽度的计算结果,二者较为接近。     

卷边加强开孔的冷弯型钢受弯构件的性能、优化及设计

冷弯型钢(CFS)受弯构件的腹板常常开圆孔,用于通过管道、电缆、水管设施和安装横向支撑等。传统在冷弯型钢腹板上开孔的构件的翼缘是不带卷边的,最近研发出新型具有加劲卷边的C型截面冷弯薄壁型钢抗弯构件。然而,目前对于新型C型截面构件的研究尚不深入,有用的试验也有限。该文采用有限元分析方法分析加劲开孔的冷弯型钢薄板和典型C截面构件的稳定性。基于弹性屈曲分析方法得出孔洞的最佳剖面,并将其应用于标准C截面构件。采用屈曲后有限元分析方法确定构件的挠曲强度。结果表明加劲孔洞能够大大提高C截面CFS挠曲强度。计划提出新的设计准则以准确计算孔洞剖面最佳的新型C截面构件的挠曲强度。     

PBL加劲型矩形钢管混凝土支管受拉节点有效分布宽度

为研究PBL加劲型矩形钢管混凝土支管受拉节点应力分布规律及其有效分布宽度,采用ABAQUS软件建立42个矩形空钢管、钢管混凝土及PBL加劲型矩形钢管混凝土节点有限元模型并进行位移加载;根据有限元计算结果拟合得到矩形空钢管、钢管混凝土及PBL加劲型矩形钢管混凝土节点的有效分布宽度表达式,将拟合公式计算值与CIDECT规范计算值和有限元计算值进行对比。结果表明:在节点受力全过程中,PBL加劲型矩形钢管混凝土节点相对于矩形空钢管节点和钢管混凝土节点的应力分布不均匀性减小;当加载位移达到3%b₀（b₀为主管宽度）时,PBL加劲型节点的有效分布宽度更大,具有更好的受力性能,支板应力分布效率ξ随主管宽厚比2γ与支主管厚度比τ的增大而减小,其中τ对ξ的影响更大;支板应力分布效率ξ随支主管宽度比β变化较小,且呈抛物线变化;拟合公式计算值与CIDECT规范计算值及有限元计算值吻合良好,验证了公式的正确性     

Experimental and Numerical Study on Buckling Behavior of a Rigidly Stiffened Plate with Tee Ribs

In the bridge structures, stiffened plates are usually designed as rigidly stiffened when the orthotropic steel box girder is used as the main load-bearing structure. Therefore, the buckling mode of stiffened plates is plate buckling which occurs in subpanel supported by stiffeners. The orthotropic steel box girder is used as the main girder for Egongyan Rail Special Bridge, which is a self-anchored suspension bridge. Plates of the steel girder are rigidly stiffened with unequal spacing open ribs, and the most slender stiffened plate is the mid web stiffened with Tee ribs. In order to ensure the safety of the bridge, the buckling behavior of the web and orthotropic steel box girder under axial compression, including ultimate strength, post-buckling behavior and failure modes, should be clearly investigated by experimental and numerical methods. The design, loading and testing methods of the 1:4 scale model of the orthotropic steel box girder are introduced in detail firstly. The orthotropic steel box girder and the stiffened web finite element (FE) models are validated by the test results, and the effects of residual stress and the magnitude of geometric imperfections are discussed roughly. Based on the validated web FE model, a detailed parametric study is performed to systematically investigate the effects of residual stress and geometric imperfections on buckling behavior of the web. The effect of shapes of geometric imperfections discussed is highlighted. Through tracing stress states, the failure modes of stiffened plate are in agreement with the experimental phenomenon to some extent. Results show that shapes of geometric imperfections have significantly influenced post-buckling behavior and failure modes of the web, but slightly affected the ultimate strength. It is advised that residual stress and geometric imperfections should be controlled to make full use of excellent performance of steel materials.     

Cold-formed steel flexural member with edge stiffened holes: Behavior,optimization, and design

Circular holes are commonly found on the web of cold-formed steel (CFS) flexural members for piping, electric-wiring, plumbing, or installing lateral bracing, etc. Traditional holes on CFS members are flat bunched without edge lips. A new generation of CFS C-section flexural members with edge stiffened holes was recently developed by the industry. However, research on the new generation C-section members is underdeveloped and available test results are limited. This paper presents finite element analyses to study on the stability of cold-formed steel thin plates and typical C-section members when edge stiffened circular holes are placed on those plates or members. Based on the elastic buckling analyses, the optimized profiles of the holes are obtained and then applied to standard C-section flexural members. The post-buckling finite element analysis is utilized to determine the flexural strength of those members. The results indicate that the stiffened holes can significantly improve the flexural strength of CFS C-sections. New design provisions are proposed to accurately predict the flexural strength of the new generation C-section flexural members with the optimized hole profiles.     

受压或受弯开孔薄板的弹性屈曲性能

开发、论证并总结了一组闭合公式,可以估算在弯矩或压力作用下,板的单个或多个开孔对其临界弹性屈曲应力的影响。公式适用于四边简支和三边简支的板(这在设计中又称为加劲板和非加劲板)。由于有限壳单元特征值屈曲分析需要运用商业有限元程序,而这些程序又不是专为结构分析而开发的,不能很方便地用于工程设计,所以可以采用这些公式作为这种屈曲分析方法的简化替代。这些公式的形式与板稳定性近似分析的经典形式相似,并通过有限壳元对其进行了参数分析并验证。有限元参数分析证实了开孔可能会导致板产生独特的屈曲模式,开孔的几何尺寸和间距可能会增加或者减少板的临界弹性屈曲应力。这些公式及其使用限制可适用于工程中通常采用的开孔形状、位置和间距,同时研究也指出,若需得到足够精确的计算,则还是有必要采用壳单元的有限元分析。     

Ultimate strength of stiffened plates with a square opening under axial and out-of-plane loads

The high strength to weight ratio and high stiffness to weight ratio of stiffened plates find wide application in aircraft structures, ship structures, offshore oil platforms and lock gates. The strength and stability of stiffened plates is highly influenced by openings and initial imperfections. The main objective is to study the behaviour of stiffened steel plates with openings up to collapse and to trace the post-peak behaviour under axial and out-of-plane loads. Four stiffened steel plates with a square opening were fabricated for testing. Angle sections were used as stiffeners. Imperfections in the plate, stiffener and overall imperfection of the whole panel were measured. All fabricated panels were tested to failure. A finite element (FE) model was developed for the analysis of stiffened plates with initial imperfections and validated with the test results. Parametric studies were conducted using the developed FE model, and interaction curves and equations were developed for the design of stiffened plates with initial imperfections and openings. The interactive effect for stiffened panels with a square opening was found to be linear, with proportional reduction of the ultimate axial load carrying capacity due to the constant out-of-plane load.