城市高架桥动力特性研究

桥梁结构的动力特性就是结构振动的基本特性,是对桥梁结构进行地震反应分析的基础.因此,对高烈度地区城市高架桥动力特性进行试验和理论研究很有必要.本文以高架桥常见的结构形式桥面连续简支梁结构为例,建立三维有限元模型,进行了模态分析并与试验结果进行对比分析.其结论可为同类型桥梁结构进行设计和分析作为参考.     

整体桥台桥梁应用及有限元分析

介绍了整体桥台桥梁的特点、存在的问题和有限元分析方法,并对一座单跨整体桥梁进行了三维有限元分析,给出了在桥梁整体升温和桥面板局部升温两种荷载模式下整体桥台桥梁的荷载效应。     

李萨如曲线拱肋的斜拉飞燕拱人行景观桥设计

针对超大跨径的曲线形人行景观桥的需求,提出一种双幅曲线形桥面的李萨如曲线拱肋飞燕式斜拉拱桥,其平面正投影为李萨如曲线图形,拱肋侧立面为飞燕式斜拉拱造型,钢管混凝土飞燕式斜拉拱肋上安装下部拱脚拉索和拱肋间上部空间缆索,形成自平衡结构体系,浮运拖拉过河,安装主拱吊索和尾部斜拉缆索,悬吊双幅曲线形桥面和中央圆环形观光平台,多...     

多塔下拉索斜拉桥静力荷载试验和计算分析

针对加有下拉索的多塔斜拉桥这种新型的桥梁结构体系,参考某长江大桥实际工程建模,通过缩尺静力实验和有限元计算分析对比加劲索加下拉索多塔斜拉桥与常规无加劲索多塔斜拉桥的静力力学性能.试验和分析表明,加下拉索多塔斜拉桥结构体系可以有效提高结构刚度,减少塔墩根部以及主梁跨中的弯距.对比试验结果,提出了最佳的下拉索设置方案.     

不同计算模型下大跨度斜拉桥静动力对比分析

以某大跨度跨海斜拉桥为研究对象,介绍了索塔、斜拉索、桥面系和边界条件的有限元建模方法。索塔和斜拉索采用相同的建模方法,桥面系采用了单主梁模型、三主梁模型及梁板组合模型3种不同的建模方法。列出了该桥梁静力位移、主梁应力状态的计算结果。通过对计算数据的比较,指出了3种有限元模型计算结果的差异,并对造成差异的原因进行了分析。将3种计算模型的前12阶频率与实测频率进行对比,得出采用梁板组合模型的结果更精确,而单主梁模型与三主梁模型的模拟方式在一定意义上是等效的。     

Active aerodynamic stabilisation of long suspension bridges

The paper describes the addition of actively controlled aerodynamic appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suspension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to make use of control analysis and design techniques, a linear model of the structural and aerodynamic motion around equilibrium is developed. The model is validated through comparison with finite element calculations and wind tunnel experimental data on the Great Belt East Bridge in Denmark. The developed active control scheme is local in that the flap control signal at a given longitudinal position along the bridge only depends on local motion measurements. The analysis makes use of the Nyquist stability criteria and an analysis of the sensitivity function for stability analysis. The analysis shows that the critical wind speed for flutter instability and divergence is increased substantially by active control.     

Dynamics of wind-rail vehicle-bridge systems

An analytical model for dynamics of wind-vehicle-bridge (WVB) systems is presented in this paper in the time domain with wind, rail vehicles and bridge modeled as a coupled vibration system. The analytical model considers many special issues in a WVB system, which include fluid-solid interaction between wind and bridge, solid contact between vehicles and bridge, stochastic wind excitation on vehicles and bridge, time dependence of the system due to vehicle movement, and effect of bridge deck on vehicle wind load and vice versa. The models of wind, vehicles and bridge are presented with wind velocity fluctuations simulated using the simplified spectral representation method, with vehicles modeled as mass-spring-damper systems, and with bridge represented by a finite element model. The interactions between wind and bridge are similar to those considered in conventional buffeting analysis for long span bridges. In considering difficulties in measuring aerodynamic coefficients of moving vehicles on bridge deck, the cosine rule is adopted for the aerodynamic coefficients of moving vehicles to consider yaw angle effect, and expressions of wind forces on moving vehicles are then derived for engineering application. To include mutual effects of wind loads, aerodynamic parameters of vehicles and bridge deck are measured, respectively, using a composite section model test and a specially designed test device. The dynamic interaction between vehicle and bridge depends on both geometric and mechanical relationships between wheels of vehicles and rails on the bridge deck. The equations of motion of the coupled WVB system are derived and solved with a nonlinear iterative procedure. A cable-stayed bridge in China is finally selected as a numerical example to demonstrate dynamic interaction of the WVB system. The results show the validity of the present model as well as wind effects on the rail vehicles and the bridge.     

下承式钢管混凝土系杆拱桥的冲击系数研究

以泰兴滨江大桥为例,根据下承式钢管混凝土系杆拱桥的结构特点,采用大型通用有限元软件ANSYS对该桥进行有限元离散。采用梁单元beam4模拟钢管混凝土拱肋（内部混凝土及外部钢管）、系杆及横梁等构件,用杆单元Iinks模拟吊杆,用壳单元she1163模拟桥面铺装层,用实体单元solid45模拟桥面系的预制空心板部分,建立了系杆拱桥的空间计算的有限元模型,进行模态分析,得到各阶自振频率及振型。建立四分之一车辆模型作用下的拱桥车桥耦合振动模型,并利用MATLAB语言编制程序,分析了移动车辆荷载作用下下承式钢管混凝土系杆拱桥的响应,系统地得到了该桥在不同车速,不同车道,不同阻尼,不同路况的振动响应等力学性能。本文所得出的主要结论和有关研究成果可为大跨度钢管混凝土系杆拱桥设计时的冲击系数取值,研究车辆对系杆拱桥的冲击性能和后期桥梁养护确定荷载效应分析提供参考。     

满堂支架现浇混凝土连续箱梁桥面平整度控制

系统地分析了影响满堂支架现浇混凝土箱梁平整度的主要因素,并以某工程满堂支架现浇连续箱梁为对象,运用大型有限元分析软件Ansys模拟桥梁结构每个施工阶段的受力情况,详细探究了满堂支架施工时桥面的平整度,提出各个影响因素相应的平整度控制对策,用以改善和提高箱梁桥面平整度的工艺,延长桥面铺装的使用寿命。     

润扬大桥悬索桥动力特性分析与实测变异性研究

对我国首座采用刚性中央扣代替短吊索设计的润扬大桥悬索桥进行了动力特性分析与实测变异性研究。首先,通过建立三维空间有限元模型,计算了30种不同伸缩缝刚度下的动力特性参数,研究了悬索桥动力特性的边界敏感性;其次,对基于环境激励的桥面模态试验分析结果以及结构健康监测系统获取的不同时期动力特性参数进行了分析,重点研究了通车前后动力特性参数的变异性,指出了部分振型自振频率发生较大变化的原因。研究结果表明:悬索桥动力特性具有较强的边界敏感性,伸缩缝刚度的变化能够引起部分动力特性参数发生较大的变化。设置中央扣后悬索桥一阶反对称振型自振频率边界敏感性增大。在对悬索桥的动力特性进行精确分析时,主梁两端边界条件不容忽视。研究成果对同类大跨度悬索桥的设计和安全评估具有重要的参考价值。     

Response of a continuous, skewed, steel bridge during deck placement

An investigation was conducted to study environmental, material and deck placement effects on the behavior of a continuous, skewed, High Performance Steel (HPS), integral abutment bridge during construction using field data and three-dimensional finite element models. The finite element models were calibrated against girder strain measurements recorded during deck placement. During calibration, the effects of temperature changes during deck placement were clearly evident and were shown to have a significant effect on the accuracy of the finite element results. Effects from hardening of the concrete deck as the pour progressed were shown to be less evident. A calibrated model was used to compare stress variations and deflections of the two outer girders when concrete was placed (1) perpendicular to the girders and (2) parallel to the skew. The influence of various parameters on numerical model results was postulated and a deck placement method was recommended.     

列车荷载作用下铁路斜拉桥索-梁相关振动研究

为了研究大跨度铁路斜拉桥的索-梁相关振动,基于拉索非线性振动理论,开发了有限元索动力单元,该单元在静力计算中为普通直杆单元,动力特性计算中可以计算拉索局部自振频率,动力时程计算中可以计算拉索非线性振动与整体结构振动的相互作用;编制了计算程序,建立了大跨度铁路斜拉桥有限元模型,同时使用索动力单元模拟斜拉索,最后研究了列车通过斜拉桥时梁、塔的带动下拉索发生索-梁相关振动的特性。结果表明:对于大跨度铁路斜拉桥,列车在设计速度范围内通过桥梁时索-梁相关振动不会导致拉索产生大幅振动。     

大跨度桥梁结构耦合抖振响应频域分析

基于结构的固有模态坐标 ,提出了用于大跨度桥梁耦合抖振响应分析的有限元CQC(thecompletequadraticcombination)方法。在合理假设基础上 ,推导了桥梁结构的节点等效气动抖振力公式。应用随机振动理论 ,提出了桥梁结构节点位移和单元内力功率谱密度和方差的计算方法。该方法采用了含 18个颤振导数的气动自激力模型 ,可以考虑自然风的任意风谱和空间相关性以及桥梁抖振响应的多模态和模态耦合效应 ,且计算效率很高。此外 ,对主跨跨度 13 85m的江阴长江大桥的耦合抖振问题进行了分析 ,得出了一些结论。分析结果表明 ,在大跨度悬索桥中 ,多模态效应和模态耦合效应对主梁的竖向和扭转位移抖振响应有显著的影响     

桥面铺装结构的受力特性分析

对于装配式预应力混凝土空心板桥,由于桥面铺装层是在刚性预制板上浇筑的混凝土,其受力情况比较复杂。采用三维有限元方法,对铺装层在空心板企口缝处的剪应力状况进行了计算分析,并对空心板和铺装层之间的粘结性能进行了探讨。研究结果为桥面铺装结构设计和材料选择提供了技术依据。     

大跨越输电塔线体系风振响应的时域分析

以规划中的世界第一高塔-舟山大跨越输电塔为工程背景,建立了塔线耦合体系的空间有限元模型,对体系的风振响应进行了时域分析,同时对输电塔线体系进行了气动弹性模型的风洞试验。通过理论计算和试验研究,将输电塔的响应分解为共振分量与背景分量,并分别考虑了输电线对这两部分分量的影响。针对背景与共振响应各自的特征,进一步提出了塔线体系的简化计算方法:背景分量的计算可以应用准静态假定,采用方差分析法得出;将塔线体系等效为悬吊摆系统,从而简化了共振分量的计算。上述两部分计算结果相叠加,即可得到塔线体系真实的风振响应。     

润扬大桥悬索桥索塔结构动力特性实测

润扬长江公路人桥是我国在建规模最大的索支承结构，索塔作为其中一个重要的结构组成部分，掌握其结构动力特性，可以完善理论分析模型，从而为全桥模型的建立和进一步建立润扬大桥结构安全健康监测系统提供最原始的指纹数据。本次测试是在严格符合各项操作规程的条件下，采用环境激励法完成的，在对测试数据进行统计分析后，获得了索塔结构动力特性，并在此基础上，修正了理论模型。然后，对模型进行了有限元模态分析，所得结果与测试结果比较，相当接近，误差极小，证实了理论模型的正确性和可靠性。并在实测结果和理论模型分析结果的基础上，建立了索塔的有限元杆系模型，通过对其进行模态分析，结果进一步论证了理论实体模型的精确性。     

Experimental and analytical system identification of Eynel arch type steel highway bridge

This paper describes a full scale arch type steel highway bridges, its finite element modelling and Operational Modal Analysis. Eynel Highway Bridge which has arch type structural system with a total length of 336 m and located in the Ayvac?k county of Samsun, Turkey is selected as a case study. The bridge connects the villages which are separated with Suat U?urlu Dam Lake. The three dimensional finite element model is constructed using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three-orthogonal directions. The ambient vibration tests on the bridge deck under natural excitation such as traffic, human walking and wind loads are conducted using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification methods are employed namely, Enhanced Frequency Domain Decomposition method in the frequency domain and Stochastic Subspace Identification method in time domain. The correlation between the finite element model and experimental results is studied. Good agreement is found between dynamic characteristics in the all measurement test setups performed on the bridge deck. It is demonstrated that the ambient vibration measurements using Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are enough to identify the most significant modes of steel highway bridges. It is seen that there are some differences between analytical and experimental natural frequencies and experimental natural frequencies are generally bigger than the others.     

Study of super long span cable-stayed bridges with CFRP components

This paper introduces new types of cable-stayed bridges with carbon fiber reinforced polymers (CFRP) stay cables and/or a CFRP bridge deck. For each of the two CFRP components, namely, CFRP stay cables and CFRP bridge deck, the key design parameters and design strategies were determined and the appropriate value of each key design parameter was suggested. Using the suggested parameter values, six types of cable-stayed bridges with a main span length of 1400 m were selected and modeled with the finite element method, through which the procedures of designing composite cable-stayed bridges with CFRP components were presented in details. From a mechanical-behavior viewpoint (static and dynamic) a comparative study of composite cable-stayed bridges with different CFRP components was performed through numerical simulations. The economical behavior of each type of cable-stayed bridges was also comparatively studied considering the varying material price. With the high strength-to-weight ratio and other advantages of CFRP materials, it was proven in this study that the use of CFRP stay cables and CFRP bridge decks in super long span cable-stayed bridges is feasible and these types of composite cable-stayed bridges could become an excellent alternative to steel cable-stayed bridges where super long spans are desired.     

某大跨度索道桥结构工程的力学性能分析验算

索道桥是以拉索作为主要受力构件,钢横梁及木板等作为局部受力构件的一种悬索体系桥梁,其作为非永久使用桥梁,目前我国还没有关于其设计施工的标准。本文以某工程大跨度索道桥为例,运用有限元软件MIDAS/civil对索力及横向稳定性进行了计算分析,并对拉索、钢横梁、锚杆的设计进行了验算,所得结果及计算过程可为类似索道桥提供参考。     

武汉大道金桥主桥的设计

为探索跨铁路站场大型变宽斜拉桥的结构特点及其关健技术,对武汉大道金桥的设计和计算分析过程进行了总结。金桥为独塔双索面预应力混凝土斜拉桥,跨径组合为（138＋81＋41）m,桥面宽39-49.9 m,塔、墩、梁固结体系;主梁采用双边箱梁截面,桥塔为混凝土结构、高79.0 m,斜拉索采用扇形空间索面布置。结构分析采用有限元软件 MIDAS进行总体受力分析,并采用 ANSYS对桥塔锚索区顶部三个节段进行局部受力性能分析和优化,通过试验及计算对该桥的抗震及抗风性能开展了专题研究。结果表明该桥的强度、刚度等各项检算值均满足规范要求。