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...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.展开更多
This paper presents a semi-active strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this control strategy, Magnetorheological (MR) dampers are pr...This paper presents a semi-active strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this control strategy, Magnetorheological (MR) dampers are proposed as control devices, a LQG-clipped-optimal control algorithm is employed. An active control strategy, shown in previous researches to perform well at controlling the benchmark bridge when uniform earthquake motion was assumed, is also used in this study to control this benchmark bridge with consideration of multiple-support excitations. The performance of active control system is compared to that of the presented semi-active control strategy. Because the MR fluid damper is a con-trollable energy- dissipation device that cannot add mechanical energy to the structural system, the proposed control strategy is fail-safe in that bounded-input, bounded-output stability of the controlled structure is guaranteed. The numerical results demonstrated that the performance of the presented control design is nearly the same as that of the active control system; and that the MR dampers can effectively be used to control seismically excited cable-stayed bridges with multiple-support excitations.展开更多
海南省陵水县陵河知音桥为双层异形景观桥,跨河段由上层桥、下层桥、支桥与中心平台交错组成。上、下层桥分别为跨径布置(74.46+93+93+78)m和(77.56+71.52+71.52+76.06)m的4跨V形刚构桥,采用单箱室斜腹板钢箱梁;中心平台为2×23.98 ...海南省陵水县陵河知音桥为双层异形景观桥,跨河段由上层桥、下层桥、支桥与中心平台交错组成。上、下层桥分别为跨径布置(74.46+93+93+78)m和(77.56+71.52+71.52+76.06)m的4跨V形刚构桥,采用单箱室斜腹板钢箱梁;中心平台为2×23.98 m 2跨预应力混凝土V形刚构平台,采用预应力混凝土箱梁;主墩(主5号墩)采用C50混凝土双肢薄壁空心墩,基础采用嵌岩桩+承台结构形式。采用钢栈桥作为施工通道及钢箱梁吊装平台,利用BIM技术优化了钢栈桥平面布置。中心平台V形墩采用斜拉扣挂支架+满堂支架支撑组合支撑体系分段施工;中心平台采用支架整体预压、混凝土分段浇筑施工。钢箱梁采用三维建模软件深化设计、平位预拼装的加工制造方案和先吊装边跨、再整体横向滑移中心段、最后分段合龙的安装方案。展开更多
针对钢箱梁桁架式纵隔板中出现的早发性、多发性、再发性疲劳开裂病害,分析桁架式纵隔板病害原因,基于能量法,提出将端部刚接斜腹杆变为端部铰接的弹性阻尼支撑处治技术。研制弹性阻尼支撑装置(Elastic-Damping Support Device,EDSD),...针对钢箱梁桁架式纵隔板中出现的早发性、多发性、再发性疲劳开裂病害,分析桁架式纵隔板病害原因,基于能量法,提出将端部刚接斜腹杆变为端部铰接的弹性阻尼支撑处治技术。研制弹性阻尼支撑装置(Elastic-Damping Support Device,EDSD),将斜腹杆局部切除并安装EDSD,通过EDSD中设置的弹性阻尼单元耗散外部荷载输入结构的大部分能量,保障结构在长期车辆荷载等作用下的安全性和正常使用性能。结合某斜拉桥钢箱梁桁架式纵隔板疲劳开裂处治需求,开展了该处治技术实桥应用,并对其进行有限元分析及实桥监测。结果表明:钢箱梁内斜腹杆局部改造安装EDSD后可大幅降低斜腹杆应力水平,有效降低斜腹杆疲劳易损部位开裂风险,增加疲劳寿命;安装EDSD的斜腹杆上的既有裂缝均无扩展。展开更多
文摘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.
文摘This paper presents a semi-active strategy for seismic protection of a benchmark cable-stayed bridge with consideration of multiple-support excitations. In this control strategy, Magnetorheological (MR) dampers are proposed as control devices, a LQG-clipped-optimal control algorithm is employed. An active control strategy, shown in previous researches to perform well at controlling the benchmark bridge when uniform earthquake motion was assumed, is also used in this study to control this benchmark bridge with consideration of multiple-support excitations. The performance of active control system is compared to that of the presented semi-active control strategy. Because the MR fluid damper is a con-trollable energy- dissipation device that cannot add mechanical energy to the structural system, the proposed control strategy is fail-safe in that bounded-input, bounded-output stability of the controlled structure is guaranteed. The numerical results demonstrated that the performance of the presented control design is nearly the same as that of the active control system; and that the MR dampers can effectively be used to control seismically excited cable-stayed bridges with multiple-support excitations.
文摘海南省陵水县陵河知音桥为双层异形景观桥,跨河段由上层桥、下层桥、支桥与中心平台交错组成。上、下层桥分别为跨径布置(74.46+93+93+78)m和(77.56+71.52+71.52+76.06)m的4跨V形刚构桥,采用单箱室斜腹板钢箱梁;中心平台为2×23.98 m 2跨预应力混凝土V形刚构平台,采用预应力混凝土箱梁;主墩(主5号墩)采用C50混凝土双肢薄壁空心墩,基础采用嵌岩桩+承台结构形式。采用钢栈桥作为施工通道及钢箱梁吊装平台,利用BIM技术优化了钢栈桥平面布置。中心平台V形墩采用斜拉扣挂支架+满堂支架支撑组合支撑体系分段施工;中心平台采用支架整体预压、混凝土分段浇筑施工。钢箱梁采用三维建模软件深化设计、平位预拼装的加工制造方案和先吊装边跨、再整体横向滑移中心段、最后分段合龙的安装方案。
文摘针对钢箱梁桁架式纵隔板中出现的早发性、多发性、再发性疲劳开裂病害,分析桁架式纵隔板病害原因,基于能量法,提出将端部刚接斜腹杆变为端部铰接的弹性阻尼支撑处治技术。研制弹性阻尼支撑装置(Elastic-Damping Support Device,EDSD),将斜腹杆局部切除并安装EDSD,通过EDSD中设置的弹性阻尼单元耗散外部荷载输入结构的大部分能量,保障结构在长期车辆荷载等作用下的安全性和正常使用性能。结合某斜拉桥钢箱梁桁架式纵隔板疲劳开裂处治需求,开展了该处治技术实桥应用,并对其进行有限元分析及实桥监测。结果表明:钢箱梁内斜腹杆局部改造安装EDSD后可大幅降低斜腹杆应力水平,有效降低斜腹杆疲劳易损部位开裂风险,增加疲劳寿命;安装EDSD的斜腹杆上的既有裂缝均无扩展。
