单箱多室斜交箱梁受力性能分析

介绍了斜交箱梁的特点,通过建立某工程的ANSYS模型,考察箱梁在自重及预应力作用下,不同斜交角对箱梁支反力、剪力滞效应的影响,并总结了斜交箱梁桥的支反力变化,得出不同斜交角、跨中横隔板对斜交箱梁桥不利截面的剪力滞效应分布规律,提出了该种桥型的设计建议。     

斜交角对公路连续斜交梁桥地震反应的影响分析

以标准跨径的两跨公路连续混凝土斜交桥为研究对象,建立动力有限元计算模型,分别进行了常遇地震影响下的反应谱分析和罕遇地震影响下的非线性时程分析,探讨了斜交角变化对连续斜交桥地震反应的影响,并得到了影响规律。     

桥台抗扭刚度及宽跨比对斜交拱桥受力的影响

通过改变桥台抗扭刚度和宽跨比,研究对斜交拱桥受力的影响。比较了1座单孔斜交拱桥和1座双跨斜交拱桥分别在自重荷载和车道荷载作用下的受力特性变化,得出增大桥台刚度能改善斜交拱桥在自重作用下的受力特性,但对单孔斜交拱桥的改善更明显;宽跨比变化对斜交拱桥的受力性能影响不大。     

T梁桥钢筋混凝土桥面板受力分析

以内蒙古宝贝河大桥静载试验为依托,使用Midas FEA建立了有限元模型,基于该模型对桥面板厚度及主梁间距两个结构参数进行分析,得到了不同桥面板厚度及主梁间距对桥面板应力与挠度的影响,指出桥面板厚度变化对桥面板底缘混凝土拉应力、铺装层顶缘混凝土拉应力影响最大;主梁间距变化对桥面板应力及挠度影响较为明显。     

斜交梁桥荷载横向分布修正系数的曲面拟合法

简要介绍查修正系数表计算简支斜交作法桥荷载横向分布的方法及其局限性,提出进行相应软件开发时,用最小二乘法对修正系数进行曲面拟合,给出了拟合结果,并讨论了该方法的优越性。     

横隔梁对连续斜梁桥的受力影响分析

根据试验桥梁的实际情况,基于ABAQUS有限元软件平台,建立桥梁上部结构的三维仿真模型,将模型数据与试验数据对比,验证模型的准确性。分析连续异形斜梁桥的横隔梁对梁体弯矩分布和截面变形影响。研究结果表明:连续异形斜梁桥由于横隔梁的存在对跨中弯矩折减的影响显著,使纵向弯矩分布更为均匀。斜梁桥的跨中截面变形有横隔梁存在时分布较均匀,但不明显。横隔梁对跨中截面变形仍然有折减作用。     

T型梁桥桥面铺装对主梁受力性能影响分析

本文以福建省永武高速上甘店大桥为工程背景,利用有限元软件Midas程序分别建立无桥面铺装,4cm、7cm、10cm厚度桥面铺装的有限元分析模型,结合依托工程的静载试验结果分析桥面铺装层对结构受力性能的影响。同时也可为桥面铺装在T型梁桥静载试验计算中的影响提供科学参考。     

半整体式桥台无缝化斜交桥的抗震性能分析

为了掌握半整体无缝斜交桥的动力特性和地震响应特点,采用MIDAS/Civil建立了湖州贯边桥的有限元模型,进行了动力特性分析,并运用反应谱法和地震时程法对无缝化斜交桥进行了地震响应分析。结果表明:梁端台后土对桥梁的约束作用随斜交角的增大而逐渐减弱;主梁梁端台后土的作用对桥梁结构是有利的,可以有效约束桥梁纵飘;在进行地震安全性分析时,用反应谱法所得的墩底内力和墩顶位移均大于时程分析法;在进行半整体无缝斜交桥的工程设计时,应以垂直于盖梁方向输入地震动计算固定支座所产生的墩顶位移来控制桥梁的抗震安全性;所得研究成果为半整体式桥台无缝化斜交桥的抗震设计和研究提供了可参考资料,对该桥型的实际工程应用和发展起到了推动作用。     

斜交连续梁桥地震位移响应及典型参数规律研究

为了揭示斜交连续梁桥的地震破坏规律,提高这类桥梁抗震设计的针对性,选取汶川震害中某典型斜交连续梁桥为原型,以支座摩擦系数、斜交角、主梁跨数、墩高为参数构建了 15个分析桥例.考虑支座滑移、挡块退化、桥台伸缩缝碰撞等非线性因素,基于OpenSEES开源程序建立模型,采用非线性时程分析方法研究了斜交连续梁桥地震位移响应特点...     

斜交桥下水流流向偏转角度的数值模拟

我国现有桥渡水文设计规范有关斜交桥的冲刷计算没有考虑桥下水流流向偏转角度的影响,从而影响计算精度。文中通过FLUENT软件对不同斜交角度、不同压缩比条件下桥渡二维流场进行数值模拟,得到流向偏转角度随斜交角度和压缩比的变化规律,为斜交桥的冲刷计算开辟了新的途径。     

Influence of ground motion characteristics on seismic response of skewed bridges

Skewed bridges are bridges with longitudinal axes at an angle to the abutments. They are more susceptible to damage during seismic events due to in-plane rotations of the girders induced, especially when pounding occurs. Most current design standards do not consider many factors that could significantly affect the response of skewed bridges, such as the skew angle and effect of the supporting soil. A bridge-abutment model with 0°, 30°, and 45° skew angles were subjected to shake table tests. Ground motions were simulated based on the New Zealand design spectra for Class C and E soil conditions. The effects of the different characteristics of ground motions on the seismic response of skewed bridges considering presence of pounding and the supporting soil were investigated. The results were also used to evaluate the recommendation of girder seat lengths specified in design specifications, e.g. the New Zealand Transport Agency (NZTA) Bridge Manual. It was found that the NZTA recommendation for seat length could potentially significantly underestimate the out-of-plane movements of the girders. In the worst case, the displacement of the skewed bridge was up to 3.48 times that of the straight bridge – much larger than the recommended value of 1.25 times.     

Fragility of skewed bridges under orthogonal seismic ground motions

The paper evaluates seismic fragility characteristics of skewed bridges under simultaneous action of orthogonal ground motion components. The effect of skew angle on bridge seismic fragility characteristics is investigated through nonlinear time-history analyses of Painter Street Overpass, a 38.5° skewed bridge located in Rio Dell, CA, and six representative bridges with skew angles varying between 0° and 50°. Ground motion incident angle is varied from 0° to 180° to investigate the effect of the direction of ground motion incidence on bridge seismic performance. Bridge seismic response is used to generate fragility curves and contours plots that quantify the sensitivity of bridge fragility characteristics on skew angle and incident angle. For any value of incident angle, bridge seismic vulnerability increases with an increase in skew angle; however, no such general trend is found to describe the effect of incident angle on bridge fragility characteristics. Results show that the variation of maximum rotation of bridge columns for an earthquake does not follow any particular trend with the change in skew angle and incident angle. Analysis-based fragility curves are further compared with empirical fragility curves generated using real-life seismic damage data of skewed bridges and a reasonable agreement is observed between these two.     

Three dimensional modeling for steel-concrete composite bridges using systems of bar elements — Modeling of skewed bridges

A new improved way for modeling steel composite straight bridges has been presented (Vayas, 2009; Vayas, 2010). The proposed model is based on the representation of steel I-girders through the use of equivalent trusses. The concrete slab is suitably represented by a set of bar elements. Diaphragms and stiffeners may also be taken into account. In contrast to the grillage model, which is usually used for the analysis of bridges, the recommended three dimensional model allows for a more reliable prediction of deformations and internal forces. This paper discusses the extension of the model to skewed composite bridges. The presence of skew makes the analysis complicated and for this reason the grillage analysis is not always recommended. Phenomena like differential deflections of the main girders during concreting and lateral displacements of the flanges can be adequately predicted using the proposed model. The new way for modeling composite bridges, using a spatial system of beam-like structural elements, can also be used for stability analysis of skewed bridges. Worked examples are provided to illustrate the set up procedure of the proposed modeling and to compare the different ways of analysis.     

斜交简支空心板梁桥拼宽静力特性分析

以跨径20m的简支斜交空心板梁桥拼宽为工程背景,运用ANSYS有限元软件建立全桥空间有限元模型,分析了在汽车荷载和新老桥不均匀沉降作用下桥梁的静力特性,比较了20cm、25cm、30cm和35cm四种不同接缝高度对受力特性的影响.分析结果认为:对于20m跨45度斜交空心板梁桥拼宽,新老桥不均匀沉降值应控制在5mm之内,...     

斜拉桥动力反应桩基础影响分析

介绍了大跨度斜拉桥动力反应分析时计算模型的建立过程及模拟桩—土相互作用的弹簧刚度的确定方法,结合工程实例对斜拉桥的动力反应中桩基础的影响作了进一步的分析。     

航站楼高架桥的横梁受力特征分析

结合航站楼高架桥横桥向较宽,横梁跨径较大的特点,建立了有限元实体模型并对横梁受力进行了分析,得出了横梁的受力特点以及横梁与其两侧箱室的相互作用关系,对类似工程具有一定指导意义。     

超大跨径斜拉桥受力特性分析

就1 600 m斜拉桥在方案试设计过程中遇到的问题进行了一些探讨,对斜拉桥跨径增大后在动力特性方面表现出与常规斜拉桥的不同进行了概念分析;此外,从静力和动力的角度分析了1 600 m斜拉桥在施工长悬臂阶段的受力情况,验证了最大单悬臂状态的施工安全性。     

Study on flutter characteristics of cable-supported bridges

In this paper, a nonlinear method is proposed to analyze the flutter stability of cable-supported bridges, in which structural geometric nonlinearity and the nonlinear effects due to the static wind-structure interactions are fully considered. A computer program NFACSB is also developed. With the criteria of total mode damping including both structural and aerodynamic damping less than zero, the critical condition of flutter can be obtained. Through the analyses on two cable-supported bridges with streamlined and bluff deck sections, flutter characteristics is explained and the intrinsic consistence of different flutter types is clarified. The effects of each aerodynamic derivative and mode coupling on flutter instability are further investigated.     

曲线梁桥的支座计算分析

针对曲线梁桥中由于支座设置不当引起的"脱空"以及支座受力不均匀,对比分析了两种支座设置形式和三种支座布置方式的支反力情况,从而得出较为合理的支座设置形式和偏心设置方式。