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1.
大跨径钢桥面铺装动响应分析 总被引：4，自引：0，他引：4
为了研究车辆随机荷载作用下的大跨径钢桥面铺装层动响应,首先根据目前钢桥面铺装的平整度现状,利用功率谱密度函数模拟桥面不平度;然后选取单轮车辆模型计算由桥面不平度引起的行驶车辆随机动荷载;最后采用瞬态动力分析方法计算了铺装层的竖向位移及最大横向拉应力等主要力学响应,并与以往的移动恒载作用下铺装层的动响应及静力计算结果做了比较、分析表明,针对铺装层而言,相邻的2块横隔板的跨中位置为最不利荷栽位置;考虑桥面不平度情况下铺装层的最大竖向位移和最大横向拉应力的峰值分别是只考虑冲击系数的移动恒载作用下的1.33倍和1.39倍、研究结果为铺装层的混合料和结构设计提供了理论依据,对桥面施工及维护提出了严格要求. 相似文献
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The seismic analysis of a rigid-framed prestressed concrete bridge in Tianjin Light Railway is performed. A 3-D dynamic finite element model of the bridge is established considering the weakening effect caused by the soft soil foundation. After the dynamic characteristics are calculated in terms of natural frequencies and modes, the seismic analysis is carried out using the modal response spectrum method and the time-history method, respectively. Based on the calculated results, the reasonable design values are finally suggested as the basis of the seismic design of the bridge, and meanwhile the problems encountered were also analyzed.Finally, some conclusions are drawn as ：1 ) Despite the superiority of rigid-framed prestressed concrete bridge,the upper and lower ends of the piers of the bridge are proved to be the crucial parts of the bridge, which are easily destroyed under designed earthquake excitations and should be carefully analyzed and designed; 2) The soft soil foundation can possibly result in rather weakening of the lateral rigidity of the rigid-framed bridge, and should be paid considerable attention; 3) The modal response spectrum method, combined with time-history method, is suggested for the seismic analysis in engineering design of the rigid-framed prestressed concrete bridge. 相似文献
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Shaking table test of pile-water-pier superstructure 总被引：1，自引：1，他引：0
The model test of seismic simulation shaking table is an important method to study the seismic design of bridge structure. In order to evaluate the seismic response and dynamic characteristics of pile-water-pier system for developing more reliable design procedures, shaking table model tests of a submerged bridge pier system, including pile groups-cap-pier and inertia mass, were conducted. Since different similitude laws corresponding to different test objectives affected the validity of test results, the similitude law with the aim to consider the effect of hydrodynamic pressure was proposed and confirmed through an actual example. Based on the test results, the effect of water around model on seismic response under seismic excitation input was analyzed and the failure level was judged by observing the variation of basic frequency. The test results indicate that the transfer function of analytical model with water is different from that without water, the natural frequency without water is always higher than that with water, and the first modal shapes are various. It is also concluded that the similitude law is suitable for practical application and the dynamic characteristics and seismic response of the structure system can be changed because of the existence of the surrounding water, which should be paid much attention in the further investigation. 相似文献
4.
高压输电线路导线跌落非线性动响应分析(英文) 总被引：1，自引：0，他引：1
为了研究机械性故障对高压输电线路耦合体系的受力影响,建立了输电线路耐张段的非线性耦合体系模型,通过导线找形非线性静力计算确定了耐张段的初始平衡状态.采用瞬态动力分析方法计算了导线、绝缘子破坏失效危险工况下的输电线路耦合体系非线性动响应.分析结果表明,上横担一组导线断裂失效对邻近端导线张力没有明显影响,对邻近端的绝缘子及铁塔横担构件的受力有较大的影响;上横担一组绝缘子破坏失效后,破坏档未破坏端导线的张力超过了技术规程中的设计值;导线的跌落对破坏档未破坏端的上横担绝缘子受力有较大的影响,而对上横担铁塔杆件没有明显的影响;在架空送电线路的设计中应该考虑绝缘子断裂的荷载工况.研究成果可为输电线路结构设计提供理论依据. 相似文献
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Translational torsional coupled model based nonlinear dynamic analysis of an NGW planetary gear train 总被引：1，自引：0，他引：1
This paper aims to investigate the nonlinear dynamic behaviors of an NGW planetary gear train with multi-clearances and manufacturing/assembling errors. For this purpose, an analytical translational ? torsional coupled dynamic model is developed considering the effects of time-varying stiffness, gear backlashes and component errors. Based on the proposed model, the nonlinear differential equations of motion are derived and solved iteratively by the Runge-Kutta method. An NGW planetary gear reducer with three planets is taken as an example to analyze the effects of nonlinear factors. The results indicate that the backlashes induce complicated nonlinear dynamic behaviors in the gear train. With the increment of the backlashes, the gear system has experienced periodic responses, quasi-periodic response and chaos responses in sequence. When the planetary gear system is in a chaotic motion state, the vibration amplitude increases sharply, causing severe vibration and noise. The present study provides a fundamental basis for design and parameter optimization of NGW planetary gear trains. 相似文献
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Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule. 相似文献
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ＩＮＴＲＯＤＵＣＴＩＯＮＣａｂｌｅ ｓｔａｙｅｄｂｒｉｄｇｅｓａｒｅｗｉｄｅｌｙａｐｐｌｉｅｄｉｎｍｏｄｅｒｎｂｒｉｄｇｅｓｔｒｕｃｔｕｒａｌｓｙｓｔｅｍ .Ｔｈｅｌａｒｇｅｓｔｓｐａｎｏｆｃａｂｌｅ ｓｔａｙｅｄｂｒｉｄｇｅｉｓｃｌｏｓｅｔｏ 1 0 0 0ｍｗｈｅｎｍａｎｙｎｅｗｍａｔｅｒｉａｌｓａｎｄｔｅｃｈｎｏｌｏｇｉｅｓａｒｅａｐｐｌｉｅｄ.Ｔｈｅｓｔａｙｃａｂｌｅｓａｒｅｉｍｐｏｒｔａｎｔｂｒｉｄｇｅｓｔｒｕｃｔｕｒｅｃｏｍｐｏｎｅｎｔｓｍｏｓｔｐｒｏｎｅｔｏｅｘｈｉｂｉｔｈｉｇｈａｍｐｌｉｔｕ… 相似文献
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刘大鹏 《石家庄铁路工程职业技术学院学报》2014,(4):1-6
以一典型单薄壁空心矩形墩连续刚构桥——王家坝大桥施工监控项目为依托,以稳定理论为基础,利用ANSYS软件建立单薄壁空心矩形墩最高墩裸墩施工阶段模型、最大悬臂施工阶段模型和成桥阶段模型,并采用不同类型单元进行模拟,分析对比各施工阶段下的稳定特征值和非线性极限荷载,总结非线性对连续刚构桥稳定的影响规律,可为施工与设计提供参考。 相似文献
11.
鉴于矮塔斜拉桥受力性能的特殊性,引入增量动力分析（IDA）和拉丁超立方体抽样（LHS）评估该结构在地震激励下发生损伤的风险概率。首先采用LHS考虑桥梁构件材料的随机性,与事先选取的地震波相结合形成桥梁-地震动样本集合;其次在确定桥梁有限元模型主要构件损伤指标的基础上采用基于蒙特卡罗（MC）抽样的IDA进行地震易损性分析和地震风险概率评估。为验证方法的正确性和有效性,对一预应力混凝土独塔双索面矮塔斜拉桥结构模型进行地震风险概率评估,结果表明:该方法既充分考虑了材料和地震输入双重随机性又避免了繁琐的积分过程,同时也提高了工程计算的效率及精度。 相似文献
12.
This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of
stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in
the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed
through numerical, calculation. It is noted that parametrically excited oscillation of a stay cable with certain, sag, inclination
angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the
natural frequency of a cable approaches to about half of the, first model frequency of the bridge deck system. A new vibration
control system installed on the cable anchorage is proposed as a possible damping system to suppress, the cable parametric
oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due
to the vibration of the deck and/or towers will be considerably reduced.
Project supported by National Natural Science Foundation of China (No. 59978044) 相似文献
13.
介绍了桥式起重机主梁设计的计算方法及校核过程。应用有限元软件建立主梁三维模型,并针对主梁进行了静力学分析。为保障主梁结构的可靠性,将主梁与端梁装配成桥架,建立了桥架整体模型,并进行了静态分析和模态分析,在确认桥架设计合理的基础上提出了改进方案。 相似文献
14.
Jian-hua SHAO Qiang GU Yong-kang SHEN 《浙江大学学报(A卷英文版)》2008,9(3):322-329
This paper presents some methods that the standard acceleration design response spectra derived from the present China code for seismic design of buildings are transformed into the seismic demand spectra, and that the base shear force-roof displacement curve of structure is converted to the capacity spectrum of an equivalent single-degree-of-freedom （SDOF） system. The capacity spectrum method （CSM） is programmed by means of MATLABT.0 computer language. A dual lateral force resisting system of 10-story steel frame-steel plate shear walls （SPSW） is designed according to the corresponding China design codes. The base shear force-roof displacement curve of structure subjected to the monotonic increasing lateral inverse triangular load is obtained by applying the equivalent strip model to stimulate SPSW and by using the finite element analysis software SAP2000 to make Pushover analysis. The seismic performance of this dual system subjected to three different conditions, i.e. the 8-intensity frequently occurred earthquake, fortification earthquake and seldom occurred earthquake, is evaluated by CSM program. The excessive safety of steel frame-SPSW system designed according to the present China design codes is pointed out and a new design method is suggested. 相似文献
15.
Reduction of roll and pitch motions is critical in improving the safety and operability of a ship. In this paper, a predictive controller for a ship equipped with two pairs of active fins is proposed for joint pitch-roll stabilization. The proposed controller is developed on the basis of ship motion and hydrodynamic force prediction (SMHFP). The SMHFP controller consists of a short-term predictor, a force estimator, and a fin angle allocator. The short-term predictor adopts an autoregressive (AR) approach and serves to forecast ship motions. Then, predicted ship motions are used in an external hydrodynamic force estimator to evaluate the expected stabilizing forces. Finally, the optimal attack angles for active fins are allocated based on external hydrodynamic forces forecasts. The control system of the stabilizing fins and SMHFP controller is integrated into the sea-keeping program. The program was developed based on a weakly nonlinear 2.5D method, which shows better efficiency and accuracy compared with conventional 2D and 3D methods. To evaluate the performance of the proposed controller, numerical simulations of the joint pitch-roll stabilization under various sea states were investigated on a ship model. The results suggest that the SMHFP controller shows satisfactory performance in reducing pitch and roll motions simultaneously. 相似文献
16.
Dynamic characteristics analysis of a misaligned rotor-bearing system with squeeze film dampers 总被引：1，自引：0，他引：1
In this paper, a dynamic model is established for a two-stage rotor system connected by a gear coupling and supported on ball bearings with squeeze film dampers (SFDs). The nonlinear dynamic behavior of the rotor system is studied under misalignment fault condition. The meshing force of the gear coupling is calculated considering the deformation of the tooth caused by torque transmission and dynamic vibration. The contact force between the ball and race is computed based on the Hertzian elastic contact deformation theory and the elastohydrodynamic lubrication theory. The supported force of SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion are rewritten in non-dimensional differential form, and the fourth-order Runge-Kutta method is employed to solve the nonlinear dynamic equilibrium equations iteratively. To verify the validity of the dynamic model and the correctness of the numerical solution method, the experimental power spectra of the rotor system under various misalignment degrees are compared with the analytical results. The effects of several important parameters, such as the lubrication of the ball bearing, the centralizing spring stiffness, the radial clearance of SFD, and the misalignment of gear coupling, on the dynamic characteristics of the rotor system are investigated and discussed mainly focusing on the system stability. The response spectra, bifurcation diagrams, and Pointcaré maps are analyzed accordingly. These parametric analyses are very helpful in the development of a high-speed rotor system and provide a theoretical reference for the vibration control and optimal design of rotating machinery. 相似文献
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首先介绍了桥上轨道结构的减振及隔振垫层原理,然后利用ansys建立在移动荷载作用下桥上轨道结构振动模型,并以外部激励的形式输入轨道不平顺。然后分析了有碴轨道结构在混凝土桥梁上的竖向动力特性,研究不同隔振垫层及参数的情况下,轨道结构的动力响应和加速度频谱,最后对桥上轨道结构的减振设计提出了建议。 相似文献
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船舶AIS是集海上船舶识别、安全监控和通信导航功能为一体的新型数字助航系统,其在甚高频上采用SOTDMA方式实现船舶动态、静态及其他相关信息收发,以确保船舶的检测与识别功能。使用USRP对AIS的船载终端进行设计与实现,以国家GB/T20068-2006标准规范为基础,完成了基于LabVIEW语言的AIS软件无线电接收机。在该接收机中,采用了两步频偏估计校正方法,有效克服了USRP平台的频率稳定度不足的缺点,并最终实现了船舶AIS信息接收、报文解析、数据库存储;同时通过在LabVIEW中嵌入开源的GIS与航海图,实现了对珠江上航行船舶的定位与可视化。该设计案例为URSP平台在“通信原理实验”及“通信系统设计”相关课程中的进一步推广使用提供了非常好的应用案例。 相似文献
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ZHANG Ri-dong WANG Shu-qing 《浙江大学学报(A卷英文版)》2006,7(12):1984-1988
INTRODUCTION Bilinear systems are a kind of important nonlinear systems with relatively simple structure, and many industrial processes can be described as a bilinear system. Thus research on the control of this kind of systems is very important. On the other hand, model predictive control (MPC) (Clarke et al., 1987) has been widely used in industrial applications and many predictive control methods focusing on bilinear systems are emerging (Bloemen et al., 2001; Fontes et al., 2004; He… 相似文献
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研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。 相似文献