车速对铁路桥梁动力响应的影响分析

针对桥梁结构对移动列车动力响应的复杂性,通过有限元分析软件ANSYS分析石太铁路一简支梁桥在不同车速下的动力响应,得出了铁路筒支梁桥在高速列车作用下的一些动力响应特性,从而为铁路简支梁桥的合理设计提供科学依据。     

Advanced dynamic finite element analysis of a skew steel railway bridge

The aim of this paper is to present advanced modelling techniques for dynamic analysis of steel railway bridges. Finite element analyses of a case study skew bridge are carried out and the results are compared with available field measurements. Initially, eigenvalue analyses of different models are carried out in order to obtain the fundamental mode shapes and bridge frequencies and to assess the capability of each model to capture the dynamic behaviour of the bridge. Single-span, three-span and full bridge models are investigated with different elements such as shell, beam and combinations of these. A very good agreement between the fundamental dynamic properties of the bridge and empirical results is found. Following the eigenvalue analyses, time history dynamic analyses are carried out using the full bridge model. The analyses are carried out for different train speeds and the strain histories are compared with available field measurements. In terms of fatigue assessment, the mean stress range values obtained from the strain histories at selected locations on the bridge members are also compared to each other. The results show that a full bridge model using a combination of beam and shell elements is a reasonably accurate and computationally efficient way of capturing the dynamic behaviour of a bridge and estimating the mean stress range for fatigue damage calculations.     

某钢板筒仓的加固计算分析和处理措施

钢板筒仓的受力较复杂,尤其是如何考虑洞口周边应力分布、加强筋和侧板的相互影响等问题,目前尚缺乏专用的分析软件。本文借助通用有限元软件ANSYS~（TM）,对某螺栓装配式镀锌波纹板钢板筒仓,在考虑了开洞和门框等细节的基础上,进行了基于规范荷载的多工况静力有限元分析,进而确定了加固方案：在底部设置钢筋混凝土环梁;在底部4环处增设内置加强筋。本文的分析方法可供同类型筒仓验算复核及加固设计参考。     

高速列车与铁路简支梁桥动力相互作用研究

通过有限元分析软件建立桥梁有限元模型,以移动车轮加簧上质量模拟车辆,对不同工况下高速行驶的列车与简支桥梁的动力响应进行了研究和比较,得出了高速列车与桥梁系统的一些动力响应特性。     

基于地震作用下连续钢桁梁桥动力响应分析

研究了某铁路连续钢桁梁桥在7级近源地震作用下桥梁跨中节点的动力响应,经有限元模拟计算,验证了该桥具有良好的抗震性能,以保证该连续钢桁架桥结构安全.     

Evaluation of a steel railway bridge for dynamic and seismic loads

In this study, dynamic and seismic assessment of a railway bridge system with four discrete spans giving service on a double track railway line and located in an earthquake-prone region in Turkey is presented. A three-dimensional computer model of the bridge was generated using a commercial general finite element analysis software. Field measurements such as static and dynamic tests as well as material tests were conducted on the bridge system. Validation of the finite element model was performed based on the results of these tests. The calibrated 3D model of the bridge structure was then used for necessary calculations regarding structural assessment and evaluation according to train loads as well as seismic loads. Additional members were proposed to transmit seismic loads to supports. The fourth span, which had a permanent imperfection due to truck collision was studied in detail. Results have shown that due to excessive amount of capacity loss, the only choice was to write off the fourth span.     

Prediction of vehicle-induced local responses and application to a skewed girder bridge

This paper proposes an innovative and flexible simulation method that predicts the dynamic responses of bridges induced by passing vehicles. The decoupled equations of motion of the vehicle-bridge system are derived from Lagrange equations and include the effect of road surface roughness, while the interaction forces between the two systems are calculated step by step, using Newmark’s method. This algorithm does not require a special finite element (FE) code and can be implemented with standard FE software and general numerical software such as ABAQUS and MATLAB, respectively. In order to illustrate the practicability of the method, an extensive case study is then presented in which some aspects of the dynamic behaviour of a skewed bridge monitored under vehicle-induced loads are investigated. After adjustment of the boundary conditions and the spectral roughness coefficient, good agreement is obtained between the bridge vibrations predicted by the numerical model and the field measurements. The validated model is further used to analyse the distinctive dynamic effects caused by the skewness. For that purpose, a reference non-skewed bridge model is prepared according to the same design as the original skewed bridge. The obtuse corner of the skewed bridge located near the loading path is found to be a critical region where the slab-negative moments, the girder stress near the sole plate and the bearing force are significantly greater than those in the reference bridge.     

Impact of track irregularities and damping on the fatigue damage of a railway bridge deck slab

The structural response of reinforced concrete slabs in railway bridges is strongly influenced by local dynamic effects and, therefore, detailed calculations of internal forces have to be performed for a realistic fatigue assessment. In this context, this paper discusses the influence of track irregularities and modal damping coefficients in the dynamic response and fatigue behaviour of a railway bridge deck slab. For that purpose, track irregularities were measured (at different instants of time) and damping coefficients were determined based on acceleration records for passing trains in a real bridge. The bridge behaviour was calculated using a train–bridge interaction methodology, considering calibrated numerical models of the viaduct and the train. The fatigue damage was quantified through the linear damage accumulation method. This methodology allowed to understand the way track irregularities and damping coefficients affect the magnitude of applied bending moments and fatigue damage in the slab.     

Dynamic response analysis of monorail bridges under moving trains and riding comfort of trains

This paper introduces an analytical procedure to derive equations of motion for the monorail train–bridge interaction based on Lagrange’s formulation to investigate riding comfort of moving monorail trains on bridges. A 15 degrees-of-freedom dynamic model is assumed for a car in a monorail train that consists of driving, steering, and stabilizing wheels. It is based on the finite element method for modal analysis using three-dimensional models for a monorail bridge. Dynamic behaviors of a rationalized monorail bridge with a simplified structural system are investigated in comparison with those of a conventional monorail bridge using the developed analytical method. The riding comfort of running trains on the rationalized monorail bridge based on ISO 2631 is estimated using 1/3 octave band spectral analysis. Observations indicate that a rational type bridge does not engender difficulties related to the riding comfort of the monorail train, even when considering the longest traveling time of passengers between terminals.     

既有桥梁粘钢加固受力特性分析

本文在既有桥梁粘钢加固的基础上,通过有限元数值分析计算,比较了粘钢加固前后在自重和汽车荷载作用下的挠度和纵向应力变化,并进行了正截面抗弯承载能力验算,评价了既有桥梁粘钢加固改造的效果。结果表明粘钢加固后钢板能够有效地参与受力,主梁受压区截面高度增大,承载力增大,受力更加合理;加固后正截面抗弯极限承载力有所提高;桥梁的整体性和刚度均有显著改善。     

Consistent virtual work approach for the nonlinear and postbuckling analysis of steel frames under thermal and mechanical loadings

The aim of this paper is to provide a consistent virtual work formulation for the nonlinear and postbuckling analysis of steel frames at high temperatures. Central to this study is the derivation of the virtual work terms for the thermal stage, in addition to those for the loading stage, based on the updated Lagrangian formulation. The incremental stiffness equation derived for the beam element, considering both the geometrical and thermal effects, is qualified by the rigid body test. The generalized displacement control (GDC) method is adopted as the path-tracing scheme for postbuckling response. Eurocode-3 reduction factors and transformed section method are both adopted for steel I-sections. Two loading cases are studied. For structures loaded gradually under constant temperature, the critical or ultimate loading strength is obtained from the load-deflection curve. For structures heated gradually under constant loading, the critical or maximum temperature that can be sustained by the structure is computed. Conclusions are drawn for the examples studied in this paper.     

钢桁架桥静力分析及地震荷载响应分析

在有限元分析软件ANSYS环境下,对建立的有限元模型某钢桁架桥的桥体在静力的作用下进行节点的位移分析。同时,在该桥体侧向施加地震谱,分析该结构的地震荷载响应,并得出一些结论。     

某悬索桥的动力特性及地震响应分析

采用大型通用结构分析程序ANSYS，结合工程实例对某混凝土桁架悬索桥进行了动力特性分析，讨论了支座条件、垂跨比、主缆刚度、吊索刚度、加劲桁架刚度、桥面系质量等因素对结构动力特性的影响，并计算了结构的地震响应。     

谈泥石流病害对铁路桥梁的影响

简要介绍了宝天段泥石流病害主要分布情况和桥梁泥石流水害情况,重点针对宝天段上行线＂9.20＂桥梁泥石流水害进行了分析,阐述了水害原因,并展开探讨,提出了防治措施,以期解决宝天段汛期安全问题,保障该段桥梁正常通行。     

钢管混凝土拱桥有限元模拟及动力分析

阐述了利用有限元分析软件ANSYS建立钢管混凝土拱桥的计算模型的方法,并利用有限元模型对桥梁进行了理论模态分析,计算出自振频率、振型等动力参数,对其振型特征进行了分析和研究,以期全面的评价桥梁结构的动力性能。     

Statistical analysis of online strain response and its application in fatigue assessment of a long-span steel bridge

This paper covers reliability assessment of the fatigue life of a bridge-deck section based on the statistical analysis of the strain–time histories measured by the structural health monitoring system permanently installed on the long-span steel bridge under study. Through statistical analysis of online strain responses in the frequency domain using multiple linear regression, a representative block of daily cycles of strain history is obtained. It is further assumed that all cycles of online strain response during bridge service are repetitions of the representative block. The rain-flow counting method is then used to determine the stress spectrum of the representative block of daily cycles. The primary assessment of fatigue life at a given value of failure probability is undertaken for the sample component in a bridge-deck section by using the classification of details for welded bridge components and the associated statistical fatigue model provided by the British Standard BS5400. In order to evaluate bridge fatigue at any value of failure probability, a modified probability model is proposed based on BS5400. The fatigue life of the considered component in the bridge-deck section is then evaluated for some other values of probability of failure which are not included in BS5400 by use of the modified probability model. The analytical results show that the modified model is practical for reliable evaluation of the service life of existing bridges under random traffic loading.     

Fire response of steel semi-rigid beam-column moment connections

This study investigates the fire response of steel semi-rigid beam-column moment connections made with H-shape beam and H-shape column. The general purpose finite element software ANSYS was adopted. The numerical model was verified by the full-scale fire tests implemented in the building fire laboratory center of the Architecture and Building Research Institute (ABRI) in Taiwan, and its results were found to agree well with experimental results. The numerical results show that the applied moments have significant effects on the stiffness of steel moment connections in addition to material properties and connection geometry.     

Testing and monitoring of a centenary arch bridge

The present article summarizes relevant aspects concerning the monitoring system adopted during a load test carried out on the Luiz I steel bridge in the city of Porto, Portugal. The instrumentation is described and some results obtained from the load test and from a short observation period before and after the test are presented. Additionally, the performance of fibre optic Bragg grating sensors is appraised in measuring field strains and temperatures. The results are compared with those given by using a bridge numerical model, in which some integrity parameters are to be assessed by the monitoring data.     

自锚式悬索桥动力特性研究

以三汊矶自锚式悬索桥工程为例,利用通用有限元分析软件ANSYS建立大桥的动力模型,计算了前16阶频率及振型,并具体分析了恒载、加劲梁刚度、桥塔刚度等结构参数,提出了自锚式悬索桥动力特性的影响规律。     

铁路钢桁斜拉桥挂索施工技术

通过计算斜拉索无应力索长和挂索牵引力,提出了短索和长索分别采用软、硬牵引相结合的技术进行挂索,并巧妙利用了桥面展索和脱空展索相结合的工艺,在斜拉索桥面展索与梁端安装时采用桥面门架与桥面牵引相结合的方法,提高了斜拉索的安装效率和质量。