To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of...To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.展开更多
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
To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable...To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable's cross section was determined by the principle of equivalent cable capacity and the girder's cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resistance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.展开更多
基金The National High Technology Research and Development Program of China (863Program) (No.2006AA04Z234)
文摘To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.
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.
基金National Natural Science Foundation of China(No.51078134)Natural Science Foundation of Jiangxi Province(No.20114BAB206010)Department of Education Foundation of Jiangxi Province(No.GJJ11449)
文摘To discuss the applicability of advanced composite carbon fiber reinforced polymer(CFRP) and ultrahigh performance concrete reactive powder concrete(RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable's cross section was determined by the principle of equivalent cable capacity and the girder's cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resistance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.
