大跨曲线钢-混凝土组合连续梁桥水平剪力分布规律分析

针对大跨曲线钢-混凝土组合梁弯扭耦合现象,建立考虑剪力键水平滑移效应全板壳单元模型,研究分析剪力键在不同荷载作用下的受力状态。分析表明:曲线组合梁桥剪力键在制动墩位置处纵、横向水平剪力最大,纵向水平剪力远大于横向水平剪力;跨中位置处剪力键受力较小,横向和纵向水平剪力基本相当。对于单箱多室截面,中腹板剪力键所受纵向剪力稍大于边腹板,横向剪力则主要由边腹板剪力键承担。     

梁格法计算双室箱梁弯曲效应的精度研究

为研究梁格法计算双室箱梁的精度,采用剪力-柔性梁格理论,建立单箱双室简支箱梁的梁格分析模型,研究了单箱双室箱梁在竖向集中力以及均布荷载作用下的弯曲效应。为对比梁格分析的精度,采用有机玻璃模型进行实测研究,并建立了基于板壳有限元的数值模型。通过对梁格模型、板壳模型和试验实测的纵向应力以及挠度值的比较得出:剪力-柔性梁格模型的计算结果总体偏小;在分析纵向应力时与试验结果的最大误差为8.8%,分析竖向挠度的最大误差为3.3%,表明梁格模型的精度偏低。考虑到剪力-柔性梁格法建模的便捷性,可以应用于结构的初步设计和力学分析。     

钢底板波形钢腹板组合箱梁桥剪滞效应分析

研究对象采用中川机场在建钢底板波形钢腹板组合箱梁桥,并将钢底板等效为混凝土底板,探讨了荷载作用对钢底板波形钢腹板组合箱梁的剪力滞效应的影响。分别对箱梁顶板、悬臂板和底板取纵向位移差函数,箱梁纵向位移差函数设为三次抛物线。运用能量变分法推导出了顶、底板剪力滞效应的体系总势能。利用最小势能原理得出了简支梁在弯曲荷载作用下的微分方程,进一步得出了集中荷载下简支箱梁位移及截面应力解。建立了实际桥梁精细化有限元模型,进行了加载试验验证。讨论了该桥跨中截面顶底板纵向正应力、剪力滞系数的变化规律。结果显示,跨中截面位移及其顶底板应力分布三者结果吻合良好。通过有限元分析和模型试验验证本文方法的正确性,为钢底板波形钢腹板剪力滞效应分析提供有效方法。     

预应力混凝土箱梁桥悬臂施工阶段剪力滞效应

在预应力混凝土连续箱梁桥悬臂施工过程中,剪力滞效应对主梁结构有极大的影响。以某单箱单室和某单箱双室截面预应力混凝土连续箱梁桥为工程背景,建立FEA实体模型对悬臂施工过程进行模拟,对比分析单箱单室和单箱双室截面箱梁在挂篮、混凝土浇筑、预应力张拉工况下的剪力滞效应,并对最大悬臂阶段悬臂根部有效分布宽度与规范进行对比分析。结果表明：实测数据与有限元计算结果基本一致,验证了有限元分析的有效性;预应力张拉能够有效降低主梁的剪力滞效应;随悬臂长度的增加,剪力滞效应在悬臂端部变大且变化幅度增大;中腹板的设置能有效降低单箱双室箱梁的剪力滞效应;设计施工时按照规范计算截面有效宽度能够有效保证结构的安全,但单箱双室截面箱梁在挂篮工况下有限元计算值略大于规范计算值,在施工时应着重注意。     

变截面双箱连续梁荷载横向分布简化计算

本文通过分析双箱之间桥面板的受力行为,建立起箱梁弯曲扭转变形与桥面板横向弯曲内力的关系式;从而隔离出单箱进行分析。用级数法求解其弯曲扭转方程得到了箱梁内力的横向分布影响线,并用此方法对通途桥变截面双箱连续梁的荷载横向分布进行了计算;计算结果与SAP84空间梁格式法作了比较。     

单箱多室波形钢腹板组合箱梁腹板剪力分配理论

提出了一种利用剪力分配系数来计算单箱多室波形钢腹板组合箱梁在横向对称竖向荷载作用下腹板剪应力的方法.首先基于波形钢腹板不抵抗轴力的特点和箱梁平截面假定,用微元体平衡方程和变形协调条件建立了单箱多室截面波形钢腹板箱梁腹板剪力流的计算方程,然后基于该方程提出了腹板剪力分配系数的计算方法.以深圳南山大桥、郑州朝阳沟特大桥、河...     

单箱三室波形钢腹板悬臂梁扭转与畸变分析及试验研究

为研究单箱三室波形钢腹板箱梁悬臂状态下的扭转与畸变性能,以乌曼斯基第二理论和箱梁理论为基础,考虑了波形钢腹板的褶皱效应对箱梁纵向刚度的影响,推导了单箱三室波形钢腹板悬臂梁扭转与畸变微分方程,并采用初参数法及弹性地基梁比拟法求解了约束扭转和畸变产生的翘曲正应力和剪应力计算式。通过1片单箱三室波形钢腹板双悬臂梁进行了偏载和对称加载试验,验证了扭转与畸变翘曲应力计算公式的正确性。最后,利用推导的理论模型,分析了梁高、箱室宽度及波形钢腹板厚度等参数对偏载作用下单箱三室波形钢腹板组合箱梁截面翘曲应力的影响。研究结果表明：提出的理论计算公式可用于准确计算单箱三室波形钢腹板悬臂梁扭转与畸变效应;悬臂梁翘曲正应力主要由畸变变形引起,而约束扭转主要产生翘曲剪应力,且悬臂梁扭转和畸变产生的翘曲正应力值和剪应力值与弯曲正应力和剪应力的比值较大,因此,单箱三室波形钢腹板悬臂状态下扭转和畸变产生的翘曲正应力和剪应力不可忽略;梁高和箱室宽度对单箱三室波形钢腹板的翘曲应力影响较为显著,波形钢腹板厚度对其几乎没影响。     

连续箱梁桥Ansys有限元分析

利用大型结构有限元分析程序ANSYS对一座预应力混凝土连续刚构桥进行空间分析,其主梁为单箱单室变截面扁平宽箱梁。对比分析在不同荷载工况下箱梁截面的受力特性,结果表明:箱梁纵向应力沿截面出现显著的不均匀性,表现了很明显的正剪力滞效应,这种不均匀性在跨中截面尤其突出。预应力空间效应及箱梁剪力滞、畸变等因素使箱梁顶、底板局部出现了较大的应力。所得的分析结果可为同类桥梁的设计和施工提供参考。     

宽幅混凝土斜拉桥箱梁剪力滞效应研究

箱梁由于具有承受正负弯矩能力强、抗扭刚度大、截面效率指标高、稳定性好等显著优点,被广泛用于桥梁结构中。但又由于其薄壁、宽翼缘的结构特征,导致箱梁在荷载作用下易产生扭转、畸变、翘曲等不同于其他开口截面的受力特征,其中箱梁翼缘的剪力滞效应问题尤为突出。因此以某宽幅斜拉桥为例,建立了板单元模型以研究单箱6室箱梁斜拉桥的剪力滞效应。计算结果表明,斜拉桥的剪力滞效应沿横桥向和纵桥向均呈现较大规律性。     

异形钢腹板组合箱梁的扭转变形性能研究

为探索异形钢腹板组合箱梁的扭转变形性能,本文以一个任意的弯曲荷载偏心荷载,将扭转载荷和变形载荷进行等效分解,推导出扭转载荷和变形载荷的计算公式,通过Midas建立了裕溪河大桥模型,在此基础上,分析大桥在偏心荷载下的扭转变形性能。数据显示:异形钢腹板组合箱梁在扭转和变形荷载作用下,控制截面的屈曲应力沿箱梁上的中心线呈反对称分布。在第二种变形荷载加载下,截面屈曲应力呈正对称的分布。对于异形钢腹板组合箱梁在单箱三室的构造下,在第一种变形荷载加载下,截面的最大变形角出现在第二室,在第二种变形荷载加载下,截面的最大变形角出现在第一室。此外,与相同材料和厚度的平钢腹板相比,异形钢腹板组合箱梁的抗扭性能相对较差,抗变形性能相对较好。     

Ingenieurmodell zum ungewöhnlichen Tragverhalten einzelliger Rechteckkästen mit linear veränderlicher Bauhöhe unter Torsionsbeanspruchung

Simplified calculation model for the exceptional load carrying behaviour of tapered box girders with rectangular cross section under torsion. Prismatic box girders get almost shear stresses due to torsional loading, if diaphragms are situated at the points of loading. Tapered box girders in contrast get high warping normal stresses with different shear stress distributions. The normal stresses can't be ignored, because they are necessary for equilibrium. In this paper firstly the exceptional behaviour is presented, based on some examples. Then an engineering model is shown to calculate the normal and shear stresses with their distributions along the girder and along the cross section. Moreover formulas for the estimation of the deformations – twist and warping deformations – are presented. The accuracy of the engineering model was checked based on comprehensive FE‐calculations.     

A theoretical analysis of the local buckling in thin-walled bars with open cross-section subjected to warping torsion

Results of a theoretical analysis of the local buckling in thin-walled bars with open cross-section subjected to warping torsion are presented. The local critical bimoment, which generates local buckling of a thin-walled bar and constitutes the limit of the applicability of the classical Vlasov theory, is defined. A method of determining local critical bimoment on the basis of critical warping stress is developed. It is shown that there are two different local critical bimoments with regard to absolute value for bars with an unsymmetrical cross-section depending on the sense of torsion load (sign of bimoment). However, for bars with bisymmetrical and monosymmetrical sections, the determined absolute values of local critical bimoments are equal to each other, irrespective of the sense of torsional load. Critical warping stresses, local critical bimoments and local buckling modes for selected cases of thin-walled bars with open cross-section are determined.     

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect of large deflection and shear lag

In order to study the mechanics behavior of a thin-walled box continuous girder with variable cross-sections, using potential variation theories, considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement, and evolving five generalized displacements with the spline function, the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation, which was solved using the Newton-Raphon iterative method. The results of the calculation show that different shear lag warp functions to the cantilever, top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably. The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal cross-sections. The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.     

非对称外倾式钢箱拱桥扁平弯钢箱梁扭转与翘曲

以正在设计中的非对称外倾式钢箱拱肋扁平钢箱弯主梁结构形式的异型钢拱桥为背景，采用空间杆系模型对该桥进行恒栽和活栽作用下扁平钢箱主粱的扭转与翘曲受力特性分析；活载影响采用空间影响面方法计算，翘曲应力按乌曼斯基（Wumnansji）理论计算。计算结果表明，在恒载和活栽作用下，异形钢箱拱桥扁平钢弯箱梁的扭转剪应力可达到钢材容许剪应力的23．4％，在设计中必须加以考虑。     

开口截面钢-混凝土组合梁弯扭性能非线性分析

在钢筋混凝土变角软化桁架模型的基础上,提出了适于分析开口截面钢-混凝土组合梁弯扭性能的三维桁架模型。在弯扭作用下,组合梁截面各单元分别处于一维应力状态(体系1)和二维应力状态(体系2),体系1用来抵抗由弯矩和扭矩引起的截面纵向应力,体系2用来抵抗由扭矩引起的截面剪应力,两者通过截面的纵向应变协调和内力平衡条件联系起来。分析充分满足平衡条件、变形协调条件和材料本构方程。通过对部分试件的计算验证,结果表明该模型不仅可以用于预测组合梁的极限强度,而且为混凝土翼板开裂后组合梁全过程分析,提供了有效途径。     

横隔板设置对两端固支箱形梁畸变的影响

采用荷载分解法将作用于箱形梁的偏心荷载进行分解,得到了畸变、刚性扭转和对称弯曲的分析荷载。利用有限元分析软件建立三维实体模型,对两端固支钢板箱形梁在承受均布荷载时,横隔板对畸变的影响作用进行分析,得到了畸变位移和畸变正应力沿梁轴方向的分布规律。通过逐步改变箱梁内横隔板的数量,考查了横隔板的设置密度与畸变的关系;并将畸变的计算结果与相同条件下按刚性扭转、对称弯曲和偏心荷载作用下的计算结果进行了比较分析,得到了反映横隔板密度对畸变效应的影响曲线。在此基础上,提出了偏心荷载作用下钢板箱形梁的简化设计计算方法。     

Behaviour and strength of hollow flange channel sections under torsion and bending

Hollow flange channel section is a cold-formed high-strength and thin-walled steel section with a unique shape including two rectangular hollow flanges and a slender web. Due to its mono-symmetric characteristics, it will also be subjected to torsion when subjected to transverse loads in practical applications. Past research on steel beams subject to torsion has concentrated on open sections while very few steel design standards give suitable design rules for torsion design. Since the hollow flange channel section is different from conventional open sections, its torsional behaviour remains unknown to researchers. Therefore the elastic behaviour of hollow flange channel sections subject to uniform and non-uniform torsion, and combined torsion and bending was investigated using the solutions of appropriate differential equilibrium equations. The section torsion shear flow, warping normal stress distribution, and section constants including torsion constant and warping constant were obtained. The results were compared with those from finite element analyses that verified the accuracy of analytical solutions. Parametric studies were undertaken for simply supported beams subject to a uniformly distributed torque and a uniformly distributed transverse load applied away from the shear centre. This paper presents the details of this research into the elastic behaviour and strength of hollow flange channel sections subject to torsion and bending and the results.     

横隔板的设置对两端简支钢板箱形梁畸变的影响分析

利用有限元分析软件ANSYS建立了箱形梁的三维分析模型,分析得到了畸变位移和畸变应力沿梁轴方向的分布规律;通过逐步改变横隔板的数量,考查了横隔板的设置密度与畸变的关系;并将畸变荷载作用时的计算结果与刚性扭转、对称弯曲和偏心荷载直接作用时的计算结果进行比较,得到了反映横隔板密度对畸变效应的影响曲线。在此基础上,提出了偏心荷载作用下钢板箱形梁的简化设计计算方法。     

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect of large deflection and shear lag

In order to study the mechanics behavior of a thin-walled box continuous girder with variable cross-sections, using potential variation theories, considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement, and evolving five generalized displacements with the spline function, the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation, which was solved using the Newton-Raphon iterative method. The results of the calculation show that different shear lag warp functions to the cantilever, top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably. The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal cross-sections.The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.