用响应面法分析装配式公路钢桥的平面结构系统可靠度

对复杂结构进行可靠性分析时,利用传统的结构可靠性分析方法可能会遇到困难,但应用响应面法可以有效地解决问题。本文利用响应面法和有限元程序ANSYS对装配式公路钢桥主桁架的挠度、弯曲应力和压杆失稳进行了可靠度分析,得到各种结构行为下极限状态功能函数的近似表达式,从而求出相应的可靠指标。通过分析计算表明,响应面法是装配式公路钢桥平面结构可靠度分析的有效方法。     

浅谈装配式公路钢桥加固方法

装配式公路钢桥因其结构简单、自重较轻、组合形式多样、结构构件可互换及重复使用,架设迅速等优点,通过不断的研究发展,由最初的军用战备钢桥发展为军民两用桥。但装配式公路钢桥较民用桥梁比有使用寿命短、通载能力低、变形大等问题,一定程度的限制了其作为民用桥梁的应用。论述了我国装配式公路钢桥在使用中存在的主要问题,研究装配式公路钢桥的加固技术,总结装配式公路钢桥加固的新方法新技术。     

HD200型装配式公路钢桥应力测试与评估

HD200型装配式公路钢桥是一种新型的贝雷式桥梁，在我国正得到广泛应用。本文对HD200型装配式公路钢桥的应力测试结果进行了总结，对钢桥的结构强度与刚度进行评估。     

200型装配式公路钢桥安全性评价及工程应用

为了评价装配式公路钢桥的安全性,使用公路钢桥结构可靠度理论和桥梁安全评价等级研究200型装配式公路钢桥。借助Matlab和Midas有限元软件,建立基于结构可靠度的极限状态方程,求解出可靠度指标;制定安全评估方法,并以工程实例进行验证。结果表明:安全性评估方法能够合理地对装配式钢桥的安全性能做出评价,可供同类工程参考。     

新型装配式公路钢桥通过部级鉴定

新型装配式公路钢桥是在引进的艾克罗组合轻型输架桥的基础上，结合我国多年生产实践经验，对原装配式公路钢桥进行了换代产品设计，是原装配式公路钢桥的改进和发展．设计中采用了正变异性银桥面板和膨胀销等新技术。正交异性钢桥面板，便桥丙平整顺直，行车噪音小，传力明确；膨胀销可以有效地减小桥跨竖向挠度，使钢桥承载力和跨径具有较大的适应能力，结构强度、稳定性和刚度都比原装配式公路钢桥有较大提高．通过一系列架设、静我试验、动载试验和通车试用，证明新型装配式公路钢桥通行条件好，而且安全可靠．钢桥街架片重量由原来的Z…     

Krupp型装配式公路钢桥的研究

现有的装配式公路钢桥主要有321型和HD200型,但是其跨径最大只能达到60m,无法满足大跨径的应急抢修工作,因此有必要开发一种新的大跨径装配式公路钢桥以满足现有的需求。德国Krupp桥是一种以三角形桁架为拼装单元的装配式公路钢桥,文章重点对其构造细节、截面尺寸进行选型分析计算,并通过Midas Civil软件建立最优方案的杆系模型,并对其强度、位移值、稳定性、施工可行性进行分析计算。结果表明:Krupp装配式公路钢桥是一种承载能力高、尺寸设计合理、拼装简便快速、结构轻巧的装配式公路钢桥产品,在施工时需对个别杆件进行补强设计,该产品分析方案为大跨径装配式公路钢桥提供了一种新的研究方向。     

响应面法在沥青路面结构优化中的应用

基于Plackett-Burman多因素筛选设计方法确定响应面的待定系数,分析影响路面结构设计指标的关键因素,用最陡爬坡试验逼近关键因素的最大响应区域,应用响应面法以费用最低、弯沉和设计层层底最大拉应力最接近设计值为目标对路面结构各个参数进行优化,得到各路面结构参数的最佳取值。通过该方法与其他路面结构设计方法的特点综合比较,可知,响应面设计方法可在保证结构可靠性前提下实现对费用的优化,并且可操作性较遗传算法和均匀设计法简便。     

HD2OO型钢桥在桥梁施工中的应用

对HD200型装配式公路钢桥与“321”钢桥对结构、受力特性做了比较、分析，说明HD200型钢桥在桥梁施工中具有广泛的应用空间。     

HD200型装配式公路钢桥

ＨＤ２００型装配式公路钢桥已试制成功，其强度，刚度、稳定和抗疲劳等方面均优于“３２１”，是目前国内同类桥梁中最先进的装配式公路钢桥。     

考虑接缝影响的机场水泥混凝土道面结构响应

接缝是机场水泥混凝土道面结构的重要组成部分，通过分析道面接缝传荷机理，考虑大型军用运输机复杂起落架构型和多轮荷载的作用特点，以伊尔-76为例，采用弹簧单元模拟道面板的接缝传荷，基于“地基-道面结构-飞机轮载”的相互作用，利用有限元软件建立了足尺9块板水泥混凝土道面三维有限元模型。应用该模型，计算了飞机多轮荷载作用下水泥混凝土道面结构的力学响应，对比了考虑与不考虑接缝的差异，并与美国EverFE2．0模型计算结果进行了对比。研究表明所建模型可较好地模拟道面接缝的作用机理，计算应力能更合理地反映道面结构的受力状况。     

公路盾构隧道地震响应的反应位移法分析

以某越江公路盾构隧道为工程背景,在利用成层反射理论分析场地地震波特性的基础上,采用反应位移法研究了公路盾构隧道的动力响应特性,其中:盾构隧道衬砌结构环向和纵向接头采用弹性铰模拟,天然地层作用在隧道结构上的剪切力和强制位移由成层反射理论动力分析程序DYNEQ获得.研究表明:由剪切力和强制位移引起的地震附加内力规律基本相当...     

大跨径悬索桥反应谱法地震响应分析

在运用规范反应谱进行大跨径悬索桥地震响应分析时,比较了组合方法、模态阶数、长周期、阻尼等因素的影响,得到一些有实用价值的结论。     

Random Response of Tractor-Semitrailer System

SUMMARY

This work describes an analytical study of the dynamic behaviour of a tractor-semitrailer vehicle. A digital computer simulation was used to describe the longitudinal, vertical, and pitching motions of the vehicle travelling over a stationary random road surface. A man-seat model was also incorporated into the simulation. Vehicle response to road irregularities has been studied by assuming two different roads for loaded and unloaded cases.

Numerical results are presented for vehicle, showing system eigenvalues, power spectral densities and root mean square values of the linear and angular accelerations and displacements. Vehicle acceleration response is compared with the ISO riding comfort standard. All results for the loaded and unloaded cases and for smooth and rough roads indicated that an uncomfortable ride would result from vehicle response.     

Random Response of Tractor-Semitrailer System

This work describes an analytical study of the dynamic behaviour of a tractor-semitrailer vehicle. A digital computer simulation was used to describe the longitudinal, vertical, and pitching motions of the vehicle travelling over a stationary random road surface. A man-seat model was also incorporated into the simulation. Vehicle response to road irregularities has been studied by assuming two different roads for loaded and unloaded cases.

Numerical results are presented for vehicle, showing system eigenvalues, power spectral densities and root mean square values of the linear and angular accelerations and displacements. Vehicle acceleration response is compared with the ISO riding comfort standard. All results for the loaded and unloaded cases and for smooth and rough roads indicated that an uncomfortable ride would result from vehicle response.     

Steady State Steering Response

The yaw rate response for a two-degree-of-freedom car model requires a family of curves for different degrees of oversteer or understeer. By use of non-dimensional co-ordinates this family is reduced to one single curve. The ordinate ρ is the ratio of yaw rate response to that of a neutral steering car at the same speed and is less than 1 for understeer and greater than 1 for oversteer. Since ρ is also the ratio of the side-slip angle response it is hence, a unique measure of the steady-state steering characteristics.     

低噪声路面的动力响应分析

为了降低道路的噪声,以某国道为依托工程,在对材料的调查分析基础上,通过构建低噪声路面动力学分析模型,并赋予依托工程的道路实际材料参数,仿真计算得到普通路面与试验路面的时间-位移,时间-速度,时间-加速度关系曲线,建立了降噪路面的时间-位移关系数学模型;通过检测普通路面与试验路面的噪声,发现2种路面材料的噪声值均呈现随车速的增加而增加的规律,得到试验路面相比普通路面可有效的降低噪声值5—6分贝,为道路噪声的降低提供了理论依据。     

基于修正反应谱高墩连续刚构桥地震响应研究

在长周期地震动低频成分的作用下,桥梁会产生剧烈的地震反应。结构在进行反应谱分析时,相关规范中反应谱并未特别考虑长周期地震动这一重要因素。通过比较发现,按规范计算的相对位移反应谱在长周期段位移随自振周期线性增加,与实际地震动记录的变化趋势和统计特征差异明显,说明按规范计算的反应谱出现严重失真现象。该文选取考虑长周期地震动因素共612条各类场地的地震记录进行统计分析,提出衰减指数线性变化的修正方法,对规范设计反应谱进行合理修正,并确定了修正反应谱公式的相关参数。通过建立某高墩连续刚构桥CSiBridge动力有限元模型对修正反应谱进行验证,在E2地震作用和考虑三向地震作用下,该文分别对桥梁进行规范反应谱、修正反应谱分析和普通地震动、长周期地震动时程分析,比较结构的位移和内力响应结果,验证考虑长周期地震动因素的修正反应谱比规范反应谱更加合理安全,可为实际桥梁的抗震设计提供参考依据。     

Vehicle Response to Stochastic Roadways

SUMMARY

Dynamic response calculations for vehicles traversing irregular surfaces are usually accomplished using frequency domain methods involving spectral densities and transfer functions. Here an alternative procedure is developed which allows direct computation of mean square values and correlations of system variables for both transient and steady-state conditions. The method is based upon the differential equation for the covariance matrix which is directly related to the state equations for the vehicle. Multiple white noise inputs can be incorporated as well as inputs at two wheels which follow the same track at a distance from one another..The method is suitable for computer implementation without the complex algebra associated with finding all necessary transfer functions and the necessity of evaluating integrals in order to find mean square values using the conventional approach. As an illustration, a simple vehicle model is worked out completely and the variation of pitch and heave motion as a function of vehicle speed is plotted.     

Vehicle Response to Stochastic Roadways

Dynamic response calculations for vehicles traversing irregular surfaces are usually accomplished using frequency domain methods involving spectral densities and transfer functions. Here an alternative procedure is developed which allows direct computation of mean square values and correlations of system variables for both transient and steady-state conditions. The method is based upon the differential equation for the covariance matrix which is directly related to the state equations for the vehicle. Multiple white noise inputs can be incorporated as well as inputs at two wheels which follow the same track at a distance from one another..The method is suitable for computer implementation without the complex algebra associated with finding all necessary transfer functions and the necessity of evaluating integrals in order to find mean square values using the conventional approach. As an illustration, a simple vehicle model is worked out completely and the variation of pitch and heave motion as a function of vehicle speed is plotted.