工字形复合曲线梁桥的性能研究

目前在计算水平弯曲的复合钢梁桥时,通常采用一种近似方法,即单个直梁的线弹性分析法,其中具有可变参数以考虑构件曲率。归纳了明尼苏达州德卢斯的一个具有较重活荷载的多跨水平弯曲工字形复合钢梁桥的现场试验数据和计算结果。将8个320kN的卡车以43种静力加载和13种动力加载的方式放置在桥上,并将试验结果与线弹性梁格分析中得到的结果进行对比。桥被设计为由强度控制,梁的应力达到了屈服应力的75%,有些部位甚至达到了最大应力,同时,对梁、隔板、水平抗风支撑、桥面板、轴承的性能和疲劳特性进行了描述。采用梁格分析以验证这些方法对于计算梁桥承载能力的有效性和准确性。     

Modeling of curved composite I-girder bridges using spatial systems of beam elements

A new way of modeling steel composite bridges has been presented by Vayas et al. (in press, 2010)  [3.] and [4.]. The proposed model is based on the representation of steel I-girders by equivalent trusses. The concrete slab is suitably represented by a set of bar elements, and the bearings by appropriate springs. Diaphragms and stiffeners may also be taken into account. In comparison to the grillage model, which is usually used for the analysis of bridges, the proposed three-dimensional model allows a more reliable prediction of deformations, internal forces, and stresses. Curved bridges display unique behavior characteristics, and for this reason a grillage analysis is not always suitable. The new way of modeling composite bridges, using a spatial system of beam-like structural elements, is applied in this paper for the modeling of curved composite bridges. Worked examples are provided to illustrate the set-up procedure of the proposed modeling and to compare its results with those of corresponding finite element models.     

Free vibration analysis of horizontally curved steel I-girder bridges

Presented herein is a finite element formulation for free vibration analysis of horizontally curved steel I-girder bridges. Stiffness as well as mass matrices of the curved and the straight beam elements is formulated. Each node of both of them possesses seven degrees of freedom including the warping degree of freedom. The curved beam element is derived based on the Kang and Yoo's thin-walled curved beam theory in 1994. A computer program is developed to carry out free vibration analyses of the various bridges. Comparing with the frequencies using the general purpose program ABAQUS, the validity of the presented numerical formulation is shown. The numerical formulation is extensively applied to investigate free vibration characteristics of the bridges considering effects of the initial curvature, boundary condition, modeling method, and degrees of freedom of cross frame. Invaluable information which help practicing engineers better understand the vibration characteristics is provided.     

弯梁桥病害分析

以独墩柱弯粱桥发生的病害为例，详细分析了独墩柱曲线梁桥病害产生的原因，提出在设计中采用弯梁桥计算模型、设置支座预偏心、使用径向限位装置等可以避免此类病害的发生，可对今后独柱墩弯梁桥的设计提供参考。     

Erection behavior and grillage model accuracy for a large radius curved bridge

The effects of construction procedures on the stresses and deformations in a large radius, horizontally curved, plate girder, bridge were examined along with the accuracy with which grillage models predicted the construction behavior. The examination included a study of the stresses and deformations during construction and a comparison of those quantities to the grillage model predictions. Results from the study indicated that, for the structure that was examined: (1) appreciable warping stresses were generated during girder erection; (2) the classical grillage model predictions were less accurate during girder erection while the “modified” model predictions were more accurate during deck placement; and (3) the predicted grillage model deflections were smaller for an exterior-to-interior girder erection procedure than an interior-to-exterior procedure.     

小半径曲线梁桥地震响应分析

以某高速公路立交匝道桥梁为例,建立曲线梁桥的空间梁单元有限元模型,研究地震动输入、结构动力特性、地震动输入方向及组合方法,分析结果表明,曲线梁桥结构复杂,相对直线桥,其振型参与质量分布离散,桥墩内力对地震输入方向比较敏感,宜采用多个方向进行地震动输入,并对结果进行组合。     

某大桥曲线箱梁悬臂施工应力监测

根据现场测试结果,分析了曲线箱梁悬臂施工过程中根部截面的应力变化规律,研究结果表明,挂篮的偏心荷载将会在箱梁翼板根部的局部位置产生较大的横向拉应力,甚至引起桥面纵向的开裂;对于曲线梁桥,箱梁两侧的腹板和翼缘板内的应力呈非对称分布,施工过程中应注意施工顺序和施工荷载对结构内力的影响。     

Bending behavior of concrete-encased composite I-girder with corrugated steel web

A partially encased composite I-girder with flat or corrugated web has been proposed to improve the structural performance of continuous composite girder under hogging moment. The flexural behavior of such structure under two points symmetric loading has been experimentally and analytically investigated. Static flexural loading tests showed that the partially encased girder improved bending strength in comparison to steel I-girder, as local bucking of steel flange was restricted by encased concrete. Especially for the corrugated web girder, the ultimate bending strength was improved about 20%, and the ductility also increased about 3 times. In addition, the limitation of width-to-thickness ratios for steel and concrete-encased composite I-girders with corrugated web were suggested to prevent premature failure due to local buckling of compressive flange. Moreover, the analytical methods of flexural strength under service and ultimate state for partially encased composite girder were proposed and verified with experimental results. It was found that the analytical bending strengths agreed well with the experimental ones at both service and ultimate state, which means the proposed analytical equations can be applied in predicting flexural strength accurately for such encased composite girder with flat or corrugated web.     

小半径曲线叠合钢箱梁桥设计要点

结合工程实例介绍了小半径钢箱梁匝道弯桥的构造特点,并用空间板壳单元对该桥进行了空间分析,根据分析结果指出设计该种桥型时应注意采取与其受力特点相适应的构造措施,以期指导实践。     

大跨度小半径连续弯梁桥结构行为分析

在现代城市桥梁工程中,特别是在城市立交枢纽工程、城市高架桥工程中,考虑桥下地面交通、管线及美观等因素,常常不可避免地要用到大跨度小半径弯桥。成都两快两射两环项目中南二环上采用了这种大跨度小半径弯桥,采用Midas Civil 2010有限元软件,用单梁单元模型和梁格法分别对其进行了计算,通过对比分析了解了其结构受力行为。     

小半径弯箱梁桥病害处治分析

以鄂州地区某弯箱梁为例,着重研究了箱梁采用体外预应力加固前后结构承载力和内力的变化情况以及支座的偏移情况,并针对弯箱梁产生的承载力不足或支座偏移病害,提出了加固处治措施,以保证加固效果。     

预应力混凝土曲线连续刚构桥结构行为分析

研究了悬臂施工的高墩大跨预应力混凝土曲线连续刚构桥在施工阶段和成桥阶段的结构行为,讨论了由于主梁平面弯曲对结构变形和应力的影响,为曲线刚构桥提供相应的设计建议和施工控制思路,具有现实意义。     

改造后双曲拱桥可靠度评估

本文以经过加固改造的福建罗源五里大桥为背景,阐述其病害情况和加固措施,用有限元软件MIDAS建立有限元分析模型。采用JC法计算结构的可靠度,结果表明加固后的双曲拱桥是可行的、安全的。     

一种钢-混组合桁架桥下弦杆节点极限承载力研究

钢-混组合桁架是一种新型铁路桥梁结构,节点受力复杂,通过对3个采用PBL连接件的钢-混组合桁架节点进行水平单调加载试验,研究了外接式节点的受力特性、破坏模式和极限承载力。基于有限元软件ABAQUS对试件进行3D模型分析,计算结果与试验结果较为吻合。研究表明：钢-混组合桁架节点受力性能良好,PBL连接件传力效果明显;钢腹杆为节点薄弱环节,增加腹杆厚度可有效提高节点屈服后强度和节点极限承载力;通过模型分析,提出的腹杆不对称的设计方法,破坏顺序明确,与3个钢-混组合桁架节点的试验结果相比偏于安全,能够满足我国桥梁抗震设计要求。研究成果可为同类节点的应用提供参考。     

曲线箱梁桥空间预应力效应分析

曲线箱形梁桥是空间复杂受力的结构体系,预应力效应一方面能提高构件的承载能力,另一方面也可能对结构带来一些不利的影响。采用三维实体单元和杆单元相结合的空间组合有限元方法,对一座两跨曲线预应力混凝土箱形连续梁桥进行空间受力分析。针对曲线箱形梁的力学特点,对空间曲线钢束摩阻损失的计算方法进行分析。采用组合有限元法和简化方法分析预应力径向力对箱梁腹板的作用效应,比较两者的计算结果差异。采用两种计算模型,分析了预应力对支座受力的影响,对径向支座间距设置和改善支座受力的方法进行了研究。根据预应力效应的分析结果,得到了一些有益的结论,为进一步完善曲线预应力混凝土箱梁桥的设计提供了依据。     

编程计算器在曲线桥梁布置中的应用

对CASIO系列fx-4800P型编程计算器快捷的计算方法进行了介绍，列出了计算程序，对该程序的特点进行了研究，并结合工程实例进行了证明，以解决现场施工测量中的计算繁琐问题。     

一种预应力曲线梁新型布筋形式的试验研究

由于存在弯扭耦合现象,预应力曲线梁桥受力十分复杂。梁内的预应力钢束为空间曲线,其线形会对曲线梁的受力性能产生显著影响。提出一种可用于曲线箱梁的预应力钢束新型布筋方式,并对采用新型和常规预应力布筋方式的两根曲线箱形梁进行受力性能试验研究。对比分析两根梁的裂缝发展规律、破坏形态、钢筋应变特点;并通过弯扭相关方程对比研究试件的复合受扭特性和承载能力。研究表明,新型布筋方式较常规布筋能显著改善箱梁的正常使用性能,但对极限承载能力影响并不显著。最后,提出进一步提高预应力效率的措施。研究结果可供预应力曲线梁桥设计和应用时参考。     

高速公路跨线桥预应力混凝土T梁动载试验研究

结合实际高速公路跨线桥预应力混凝土T梁动载实验检测的实验过程及实验数据,研究了该跨线桥梁结构的强度和刚度,并采用动载实验测定了桥梁的固有频率、阻尼比、冲击系数等参数,以综合评价桥梁的动力性能,指导运营过程中的桥梁维护及检修。     

Study of horizontally curved bridge girders with tubular top flanges

A system of I-shaped steel plate girders [i.e., conventional I-girders (IGs)] with cross frames between girders is widely used in curved bridges in the USA. A conventional IG has low torsional stiffness and strength, so before it is braced by cross frames, it develops large deformations and stresses under its own weight if unsupported within the span; temporary shoring is usually required during erection of a curved conventional IG bridge. An I-shaped girder with a hollow tube as the top flange (i.e., a TFG1) has larger torsional stiffness and strength than a conventional IG, resulting in improved behaviour and simpler curved bridge erection. In this paper, curved TFG1 bridge systems are analysed and compared with corresponding conventional IG systems. The advantages of curved TFG1 systems are (1) individual curved TFG1s have smaller deformations and stresses than corresponding conventional IGs during erection, and can carry their weight across the span without temporary shoring or bracing within the span; (2) curved TFG1 systems have smaller second-order effects than corresponding conventional IG systems; (3) curved TFG1 systems require lighter cross sections or fewer interior cross frames than corresponding conventional IG systems.     

碳纤维在Ⅰ字梁组合微弯板梁桥加固中的应用

分析了Ⅰ字梁组合微弯板桥开裂破损的主要原因，重点阐述了用粘贴碳纤维加固危桥的施工方法和程序，并结合某大桥整治加固实例及其试验结论和效益，证实了这一加固措施的可行性。