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1.
抖振是桥梁在风荷载作用下的一种经常性的限幅振动。对于长大跨度桥梁在计算其抖振响应时不得不考虑自激力的影响，而自激力的计算方法不一，且其计算过程复杂，繁琐。本文根据抖振计算理论，研究一种自激力的实用计算方法，并对军山斜拉桥进行自激力计算。 相似文献
2.
The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent
wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite
element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind
model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since
the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with
data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different
speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for
ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different
wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be
closed as the mean wind velocity reaches 30 m/s. 相似文献
3.
A 3D finite element (FE) model for the Sutong cable-stayed bridge (SCB) is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges. 相似文献
4.
武汉军山大桥是跨越长江的中跨跨径很大的斜拉桥，在脉动风作用下，其线性抖振响应较大，动力放大系数基本上大于2。为了比较该桥非线性抖振响应与线性抖振响应的差别，本文根据某地短期的实际风速时程记录资料，在一定的概率下，对该地区100年一遇的极值风速时程进行抖振分析比较。计算结果表明，对于该桥说来非线性影响不是很明显。 相似文献
5.
The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges
is explored in this paper. By installing the TLCD in the bridge deck, a mathematical model for the bridge-TLCD system is established.
The governing equations of the system are developed by considering all three displacement components of the deck in vertical,
lateral, and torsional vibrations, in which the interactions between the bridge deck, the TLCD, the aeroelastic forces, and
the aerodynamic forces are fully reflected. Both buffeting and flutter analyses are carried out. The buffeting analysis is
performed through random vibration approach, and a critical flutter condition is identified from flutter analysis. A numerical
example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective
device for suppressing wind-induced vibration of long span bridges, either for reducing the buffeting response or increasing
the critical flutter wind velocity of the bridge. 相似文献
6.
伸缩缝刚度对大跨度悬索桥动力特性的影响 总被引：1，自引：1，他引：0
伸缩缝作为大跨度桥梁与引桥之间的重要连接构件,其抗推刚度及可能存在的变异性对主桥及引桥动力特性的影响不可忽略。本文建立了大跨度悬索桥及引桥的有限元模型,采用弹簧单元模拟加劲梁与引桥箱梁之间的伸缩缝,分析伸缩缝刚度对悬索桥及引桥自振特性及其地震响应的影响规律。分析结果表明:伸缩缝刚度对加劲梁的横弯振型、竖弯与纵飘耦合振型的频率有明显的影响;伸缩缝刚度的变化会导致加劲梁与引桥的振型相互耦合,同时这些振型的频率发生相应的突变,当伸缩缝刚度较大时,加劲梁两个竖弯与纵飘的耦合振型解耦成为独立的竖弯和纵飘振型;当引桥与悬索桥加劲梁的纵飘振型发生耦合时,在纵向和竖向地震作用下的悬索桥及引桥的地震响应达到最小。伸缩缝刚度对悬索桥动力特性影响的分析可为悬索桥的模态参数确认、损伤识别、抗震性能分析提供有价值的借鉴。 相似文献
7.
大跨度悬索桥几何非线性主要来自3个方面：缆索垂度效应、梁柱效应、大位移引起的几何形状变化。鉴于地震波高频成分振幅大,低频成分振幅小的特点,很难对地震作用下大跨度悬索桥几何非线性的影响做出定性判断。目前大跨度桥梁的几何非线性研究主要集中在斜拉桥,且不同的学者得出了不同的结论。本文以逐级加大振幅的Ⅳ类场地多条地震波为激励,通过对称与非对称的2座典型大跨度悬索桥的几何非线性影响对比分析,探讨了几何非线性对大跨度悬索桥重要地震响应量的影响程度及其原因,并提出了相应的抗震设计参考建议。 相似文献
8.
四渡河大跨悬索桥空间地震响应分析 总被引：2，自引：0，他引：2
非一致激励输入对大跨结构响应有着较大影响。本文以四渡河悬索桥为背景,首先根据该桥动力特性对规范反应谱进行调整,基于修正反应谱并考虑相位非平稳性合成地震动位移;然后编制了调索程序来确定有限元模型的初始平衡构型;采用时程法,分别分析了在纵桥向、横桥向以及竖向的非一致激励(行波输入、多点输入)下的悬索桥地震响应。计算结果表明,纵向非一致激励输入增大了悬索桥的地震响应,横向、竖向非一致激励输入的影响有增有减。 相似文献
9.
Structural health monitoring of long-span suspension bridges using wavelet packet analysis 总被引：1，自引：0，他引：1
During the service life of civil engineering structures such as long-span bridges, local damage at key positions may continually accumulate, and may finally result in their sudden failure. One core issue of global vibration-based health monitoring methods is to seek some damage indices that are sensitive to structural damage. This paper proposes an online structural health monitoring method for long-span suspension bridges using wavelet packet transform (WPT). The WPT- based method is based on the energy variations of structural ambient vibration responses decomposed using wavelet packet analysis. The main feature of this method is that the proposed wavelet packet energy spectrum (WPES) has the ability to detect structural damage from ambient vibration tests of a long-span suspension bridge. As an example application, the WPES-based health monitoring system is used on the Runyang Suspension Bridge under daily environmental conditions. The analysis reveals that changes in environmental temperature have a long-term influence on the WPES, while the effect of traffic loadings on the measured WPES of the bridge presents instantaneous changes because of the nonstationary properties of the loadings. The condition indication indices VD reflect the influences of environmental temperature on the dynamic properties of the Runyang Suspension Bridge. The field tests demonstrate that the proposed WPES-based condition indication index VD is a good candidate index for health monitoring of long-span suspension bridges under ambient excitations. 相似文献
10.
因大跨径悬索桥梁具有较大的跨越尺度,同时墩柱基础所处场地条件也存在差异,所以对其进行地震响应分析时需考虑局部场地效应。为了正确分析场地效应对大跨度桥梁的地震响应,以某悬索桥为研究背景,采用MIDAS/CIVIL有限元软件,建立该悬索桥的有限元模型,在考虑地震动的局部场地效应情况下列举9种不同的计算工况,对大跨度悬索桥进行时程分析,通过控制一个塔墩处场地类别,改变另一个塔墩处的场地类别来分析场地效应对桥梁跨中位移和弯矩的影响。研究结果显示:场地效应对悬索桥的跨中位移和弯矩存在一定影响,不同的场地条件对桥梁同一位置的破坏程度不同。 相似文献
11.
为研究大跨刚构-连续梁桥在高烈度地区的地震响应,选取羊记沟左线大桥为工程背景,利用Midas软件建立多个有限元模型,考虑纵、横桥向的水平地震波输入,比较反应谱与时程分析结果,获得结构动力响应特点,为大跨刚构-连续梁桥的抗震设计提供参考依据。结果表明:刚构-连续体系仅单墩刚构时不宜采用反应谱分析,高烈度地区桥梁进行地震响应时程分析时,选用与场地适应的地震波的同时,应考虑采用本地地震参数转化人工波作为地震激励源。桥墩不等高时,可通过改变墩截面形状及其与主梁连接方式调节内力分布,避免矮墩刚度大导致的内力集中。 相似文献
12.
大跨刚构桥结构桥跨较长和受力复杂。为提高抗震性能,需要对加固前后的桥梁进行抗震性能研究。以某双肢薄壁型高墩大跨度刚构桥为背景,采用ANSYS程序APDL语言,对结构进行合理的参数选取、网格划分和边界约束,结合抗震等级和桥梁规范等有关规定,研究整体结构在地震作用下的变化规律。通过沿墩高方向获取节点的方法,确定在地震作用下,各节点的最大位移从下到上逐渐增大。选取桥墩双肢相同部位各节点进行横向比较,总结得出双肢薄壁桥墩具有平分荷载和延长寿命的特点。为提高桥梁整体抗震性能,采取联结桥墩增大截面的方式进行加固,对比加固前后两模型在同一地震作用下的结构响应,得出该方法在提高结构整体刚度方面,效果显著。 相似文献
13.
The structure analysed herein is a tower and pier system of a long-span suspension bridge. The tower shaft is modelled to allow classical normal modes decomposition in order to reduce higher modes. The pier is assumed to be rigid body free to translation as well as to rocking motion, being reacted by the surrounding soil compliance that is derived from a continuum mechanics approach. Linear and non-linear soil and structural dynamic interaction is dealt with by random vibration theory with use of the linearization technique and complex modal analysis. Primary interest is placed on the investigation of the dynamic characteristics of the total interaction system and the rms response with change of the soil condition and input excitation level. Also discussed is the approximate response analysis, using classical normal modes for the interaction system, for purposes of practical design. 相似文献
14.
采用Monte-Carlo台风随机模拟算法模拟台风风场特性并根据风荷载规范良态气候风环境参数建议的取值,在大气边界层风洞中利用被动紊流发生装置再现了广州新光大桥桥位处良态和台风两类气候模式风环境特征,详细比较了两类风环境新光大桥施工和运营状态、设计风速等因素对于新光大桥跨中主梁、主拱肋和施工塔架风致抖振响应的差异,初步解释了抖振响应差别的主要原因。 相似文献
15.
16.
高墩大跨连续刚构桥梁地震易损性分析 总被引：4，自引：1，他引：3
基于增量动力分析方法,通过非线性地震反应分析,得到整体结构的破坏特征和易损位置,分析适用于高墩大跨连续刚构桥的损伤指标.对高墩大跨连续刚构桥进行整体结构的地震易损性分析时,采用应变作为墩柱损伤指标,位移作为支座损伤指标,绘制了基于整体性能的全桥易损性曲线. 相似文献
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18.
The dynamic response of single span simply supported bridge decks subjected to the passage of vehicles is examined. A modal analysis approach is adopted that is based upon a finite strip idealization of the deck. The vehicle is modelled as a rigid body supported at two points by a suspension idealization that accounts for the effect of tyre stiffness and the frictional nature of real suspension systems. Results are presented for an orthotropic slab deck and a box girder deck that illustrate the effects of (i) the initial precompression of the suspension system as the vehicle enters the span, (ii) the ratio of the vehicle's natural frequency to that of the bridge deck and (iii) a bridge deck surface profile that is not perfectly horizontal. 相似文献
19.
地震可靠度是桥梁抗震研究中的重要问题。基于随机分析的响应面理论和规范反应谱法,提出了一种分析具有随机结构参数的桥梁地震可靠度的方法,研究了结构的破坏准则及其极限状态方程,计算了高墩大跨连续刚构桥在地震激励下设计基准期内的动力可靠度。分析时考虑了结构参数和场地土的随机性,分别计算了连续刚构在多遇地震、设防地震和罕遇地震作用下的失效概率,得到了结构在设计基准期内,"三水准设防标准"条件下的地震可靠度。结果表明,该桥设计满足抗震规范要求。 相似文献