Lateral-torsional buckling of box beam with corrugated steel webs

Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.

Distortional buckling analysis of steel-concrete composite box beams considering effect of stud rotational restraint under hogging moment

Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are essential factors affecting SCCBB distortional buckling.Based on the stationary potential energy principle,the analytical expressions for the rotational restraint stiffness(RRS)of the web upper edge as well as the RRS and the lateral restraint stiffness(LRS)of the bottom plate were derived.Also,the SCCBB critical moment formula under the hogging moment was derived.Using twenty specimens,the theoretical calculation method is compared with the finite-element method.Results indicate that the theoretical calculation method can effectively and accurately reflect the restraint effect of the studs,top steel flange,and other factors on the bottom plate.Both the RRS and the LRS have a nonlinear coupling relationship with the external loads and the RRS of the web’s upper edge.Under the hogging moment,the RRS of the web upper edge has a certain influence on the SCCBB distortional buckling critical moment.With increasing RRS of the web upper edge,the SCCBB critical moment increases at first and then tends to be stable.

THE APPROXIMATE ANALYTICAL SOLUTION FOR THE BUCKLING LOADS OF A THIN-WALLED BOX COLUMN WITH VARIABLE CROSS-SECTION

For a thin-walled box column with variable cross-section, the three governing equations for torsional-flexural buckling are ordinary differential equations of the second or fourth order with variable coefficients, so it is very difficult to solve them by means of an analytic method. In this paper, polynomials are used to approximate the geometric properties of cross-section and certain coefficients of the differential equations. Based on the energy principle and the Galerkin's method, the approximate formulas for calculating the flexural and torsional buckling loads of this kind of columns are developed respectively, and numerical examples are used to verify the correctness of the solutions obtained. The results calculated in this paper provide the basis for demonstrating the stability of thin-walled box columns with variable cross-section. This paper is of practical value.

Seismic performance of double-skin steel-concrete composite box piers: Part Ⅱ—Nonlinear finite element analysis

An accurate finite element （ FE） model was constructed to examine the hysteretic behavior of double-skin steel-concrete composite box （ DSCB） piers for further understanding the seismic performance of DSCB piers; where the local buckling behavior of steel tubes, the confinement of the in-filled concrete and the interface action between steel tube and in-filled concrete were considered. The accuracy of the proposed FE model was verified by the bidirectional cyclic loading test results. Based on the validated FE model, the effects of some key parameters, such as section width to steel thickness ratio, slenderness ratio, aspect ratio and axial load ratio on the hysteretic behavior of DSCB piers were investigated. Finally, the skeleton curve model of DSCB piers was proposed. The numerical simulation results reveal that the peak strength and elastic stiffness decrease with the increase of the section width to steel thickness ratio. Moreover, the increase of the slenderness ratio may result in a significant reduction in the peak strength and elastic stiffness while the ultimate displacement increases. The proposed skeleton curve model can be taken as a reference for seismic performance analyses of the DSCB piers.

SIMPLIFIED ANALYSIS METHOD FOR ULTIMATE LOAD CAPACITY OF WEB PLATES OF BOX GIRDERS

The prosperous post buckling load capacity of web plates of box girders can be used.In this article,the post buckling behaviour of web plates of box girders under different loading conditions is theoretically analyzed and on the basis of domestic and overseas design codes of steel structures,the corresponding simplified analysis methods are put forward for the engineering design or code revision.It is proved that the simplified methods are safe,efficient and practicable through the comparison between several results.

Shear deformable finite beam elements for composite box beams

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

A comparative study on the hull strength of a ship with thin-walled box girders

Based on the Finite Element Analysis and Thin Walled-Box girder Mechanics, two design concepts of adding box girders under main deck in order to increase the hull strength of ship are presented. By comparison and analysis on the longitudinal strength, torsion strength and deck buckling between designed concepts and the original concept, it is found that by adding box girders under the main deck, the weight of hull structure is increased by lower than 10%, but the stress on the plate of the main deck is reduced by about 10%, the stress on the plating of the second deck is reduced about 20%. The shear stress on the plating of both of the main deck and second deck is reduced, but the shear stresses in several nodes are increased. Also the capability of resisting damage to ship is obviously increased by adding box girders under the main deck. The deck buckling is also increased by more than 90%. Consequently, the box girders added under the main deck are useful and effective to increase the strength of hull and ship survivability.

Study on the Mechanical Properties of Irregular Curved Steel Box Girder for City Viaduct

This paper deeply analyses the influence of different local tectonic on stress performance of spatial curved steel box Girder Bridge, using the finite element analysis software to establish space finite element model of this bridge, calculation and analysis were made on the bridge of the strength, stiffness. It has certain reference value for guiding engineering design, have a good foundation for the mechanical properties and stability of linear and nonlinear further study of curved steel box girder.

钢箱拱桥斜拉扣挂施工法拆索工序研究

斜拉扣挂体系钢箱拱桥拱肋合龙后需进行拆索工作,拆索时桥梁各构件均会产生应力变化从而影响结构安全性。为探究钢箱拱桥合理的拆索顺序及拆索时可能出现的极限不对称状态,以车田江大桥为实际工程背景,建立有限元模型,分别模拟四种拆索方案对拱肋应力及位移的影响。发现当从拱顶向拱脚依次拆索时,扣索索力的增幅最小;相反,若从拱脚向拱顶依次拆索,则会导致拱肋的竖向位移和应力极值达到最大。因此,从拱顶向拱脚依次拆索的方案最符合实际施工需求。采用Midas/Civil软件对几种极限不对称拆索状态进行模拟,结果表明:扣索、背索的拆除应尽量同步进行,以确保结构稳定。同时,两岸的拆索进度差异以及左右两幅的拆索进度差异都应控制在1束索以内,以减小对桥梁结构的不利影响。

承插型盘扣式支架在桥梁施工中的应用研究

为提高承插型盘扣式钢管支架能更好地在桥梁工程中的应用效果。该文结合福建省尤溪县刘坂大桥现浇箱梁施工实践,探究承插型盘扣式钢管结构设计、搭设管理及施工中的注意事项,通过与普通扣件式钢管脚手架的对比,结果表明承插型盘扣式钢管脚手架有材质好、安拆方便、稳定性高、安全性高和经济合理的特点。因此在桥梁工程中将承插型盘扣式钢管支架引入现浇预应力混凝土连续箱梁施工环节中很有必要。

考虑局部屈曲加劲钢箱形构件极限承载力的纤维梁柱模型

大型桥梁加劲钢箱形构件的极限承载力会受到板件局部稳定性能的影响,而目前尚缺乏成熟的可直接计入局部屈曲的高效计算模型。归纳总结国内外钢构件计算方法对局部屈曲的处理方式,明确以有效应力法即采用板件(或加劲板)平均受压应力-应变曲线简化局部屈曲效应的研究思路。通过有限元程序ANSYS二次开发钢板拉压非对称本构模型,提出一种可直接计入局部屈曲的纤维梁柱模型。材料本构模型中受压应力-应变曲线通过小型的加劲板板壳模型得到,且全面考虑了焊接残余应力与几何缺陷。搜集已开展的钢箱梁、钢桥塔及钢拱肋的稳定性试验,采用提出的纤维梁柱模型、板壳模型与传统弹塑性梁柱模型进行分析,展示截面纤维划分策略,验证文中纤维梁柱模型的可靠性与高效性;通过设置不同的缺陷参数,探讨缺陷水平与局部屈曲对各个构件极限承载力的影响。研究表明,随着缺陷水平的严重,局部屈曲会显著降低极限承载力,提出的纤维梁柱单元模型能够有效地预测加劲钢箱形构件的极限承载力,具有较广泛的应用前景。

麻纤维/聚乳酸包装盒模压成型工艺与性能研究

采用模压成型工艺制备了麻纤维/聚乳酸复合材料包装盒,研究了模压压力、加压速度、模具温度对包装盒的拉伸强度与翘曲变形的影响,分析了产生相应变化的微观机理。实验结果表明,在一定范围内,适当增加模压压力,有利于提高复合材料包装盒的力学强度,降低翘曲变形;增加加压速度,对复合材料包装盒力的学性能的影响不大,但会增加翘曲变形;模具温度为50℃时,包装盒的翘曲变形最小。

整孔现浇箱梁模板支撑架计算及分析初探

现浇箱梁施工具备场地布置灵活、施工简便的优点,针对现浇箱梁模板支撑架设计计算是确保结构稳定性及施工质量的重要前提。论文结合云南省某山区公路桥梁工程开展碗扣式支架现浇箱梁施工关键技术分析,并且对支架在不同荷载组合作用时进行相关验算。研究结果表明,支架立杆稳定性及地基承载力均满足技术规范要求,碗扣式支架现浇施工具有良好的适用性。

现浇箱梁施工技术在市政工程中的应用

以具体工程为实例,对现浇箱梁支架的搭设参数进行了验算,对支架的地基处理措施进行了分析,并就模板工程、箱梁混凝土浇筑、预应力张拉等施工技术要点展开了详细的研究,以提高桥梁工程的施工质量和效率,保证大桥的施工安全,充分发挥现浇箱梁施工技术优势。

Z型承插型盘扣式钢管满堂支撑体系在桥梁现浇箱梁施工中的应用

本文通过具体工程实例,将Z型承插型盘扣式钢管作为桥梁现浇混凝土箱梁满堂支撑体系的经验进行总结,给出了支撑体系的设计参数取值、工艺参数及构造要求,并对施工流程、施工方法、安全保证措施等进行了说明,供同类项目参考。

跨线桥高墩现浇连续箱梁支架关键施工技术研究

模板支撑体系是用于在建筑施工中支撑混凝土浇筑的临时结构系统,以保持构件形状稳定性并确保最终质量,在桥梁建设过程中起到至关重要的作用。本文旨在研究城市高墩立交桥梁现浇施工中盘扣式满堂支架工艺的应用,以某项目为背景,设计计算支架系统,并详细分析跨线桥高墩现浇连续箱梁盘扣式满堂支架施工工艺及其关键环节。实践验证显示,该支架系统在力学性能和经济方面具备显著优势,为跨线桥高墩现浇连续箱梁支架施工提供了坚实基础。

波形钢腹板箱梁剪切屈曲特性

研究了波形钢腹板箱梁的剪切屈曲特性。基于有限元数值模拟结合相关屈曲理论的方法,计算了波形钢腹板的临界屈曲应力,并与相应理论公式计算所得的各类屈曲应力结果进行对比。同时,改变波形钢腹板的主要几何参数尺寸,研究各种几何参数对波形钢腹板箱梁剪切屈曲性能的影响。研究结果表明:波形钢腹板箱梁的临界屈曲应力与波高基本无关;波形钢腹板的直板段水平长度不应设置过大,以防止结构发生局部屈曲失稳;适当增大波形钢腹板的水平折叠角可以有效防止结构发生整体屈曲失稳;增大腹板厚度可以有效提高结构的抗屈曲性能,特别是抵抗局部屈曲失稳的能力;腹板高度过高时结构容易发生整体屈曲失稳。

基于SolidWorks的卡扣快装箱有限元分析

目的木制包装以其轻质高强的特性被广泛应用于大中型机电产品的外包装,且其材料符合绿色可持续包装的特点,为了避免在性能测试过程中浪费材料,采用有限元分析对其受力状态进行模拟。方法通过SolidWorks软件对1500 mm×800 mm×733 mm卡扣包装箱进行建模,在Simulation插件中进行静态力测试、跌落测试,并获得应力云图、应变云图、位移云图及相关数据。结果在对卡扣快装箱进行有限元分析后,得到了箱体应力、应变、位移云图及最大应力、应变发生点的坐标。结论卡扣箱的底板、托盘一体化可以降低卡扣箱底板产生的应力,在静态力作用下的最大应力发生点与跌落过程中的最大应力发生点位置不同。

波形钢腹板PC组合箱梁的结构特点

随着桥梁跨度的增加 ,减轻上部结构自重便成为首要问题。波形钢腹板PC组合箱梁是一种新型的钢 混凝土组合结构。这种结构能够实现主梁的轻型化 ,进而减轻下部结构的工程量。通过对这种结构在国外的工程研究 ,本文介绍了这种箱梁的波形钢腹板和预应力体系的构造特征 ,并着重分析了箱梁的轴向变形、弯曲应力、钢腹板的局部屈曲、整体屈曲、合成屈曲稳定性以及扭转等力学特性 ,并以日本的松木七号桥和其他实桥为例 ,进一步介绍这种箱梁的结构特点及施工方法。

奥氏体型不锈钢焊接箱形截面轴压构件整体稳定性能试验研究

为了研究奥氏体型不锈钢材轴心受压构件的整体稳定性能,对6根奥氏体型不锈钢焊接箱形截面柱进行了轴心受压试验研究,在试验前对试件的几何初弯曲进行了测量,在试验过程中对荷载初偏心进行了量测。基于试验结果,分析了该类型构件的失稳破坏形态和整体稳定承载力,并与欧洲钢结构规范和中国钢结构规范进行了对比。结果表明此次试验数据高于欧洲钢结构规范和中国钢结构规范的设计曲线,设计曲线较为保守。