Stability Of Bridge Structure Research Articles

PMFSE: a video phase-based micro-vibration measurement algorithm for bridge cables in complex background

The cable serves as the primary structural component in cable-stayed bridges, suspension bridges, and other cable-supported bridge designs. Accurate measurement of cable tension holds paramount importance for ensuring the overall safety and stability of bridge structures. Cable tension can be inferred from the vibration frequency, making precise measurement of cable vibration frequency of utmost practical significance. Presently, video-based methodologies, such as phase-based vibration extraction, present notable advantages in terms of speed, efficiency, and non-contact capabilities over conventional acceleration sensor approaches. However, these methods face challenges in accurately discerning the micro-vibration of cables in complex background interference. To address this problem, a phase magnification-based feature signal extraction (PMFSE) algorithm is proposed, which is suitable for detecting small vibration in complex background. The overall idea is to combine the small vibration enhancement method in spatial domain with the signal separation method in time domain. Specifically, in the spatial domain, edge phase information is amplified through phase amplitude weighting and phase enhancement techniques to mitigate non-edge noise. In time domain, cable signals are extracted based on distinguishing features between the cable signal and noise signal. The efficacy of PMFSE is evaluated in various outdoor experiments. Compared with the state-of-the-art methods, PMFSE exhibits substantial improvements on the cable micro-vibration frequency measurement in complex background.

Study on the improvement of the torsional bracing system designing process for steel shaped I simply supported beam bridge

For a long time, the steel bridge structure has been concentrated in the highway and bridge construction industry because of several advantages like high strength material, simple manufacture, and rapid construction. However, this structure still has a few remarkable disadvantages when designing the bridge structure and one of them is the overall stability of the main girders in the construction stage. This research illustrates that a system of discrete bracing along the girders’ length adopted to handle the problem effectively. From the result, the optimally designing process of the bracing system for Steel I girder simple span bridges verified against the finite element method (FEM). However, the frame forming the bracing system has not been checked by the specific process yet, especially the compressuon member, which can cause the instability of each bracing appurtenance in both the construction and exploitation stage. Therefore, the continuing research significantly adds checking the load capability and buckling of compression frames. The expected result in this research is as follows: 1) Checking members of the bracing system added in the design process. 2) The members of the bracing system promote their ability of resisting the lateral-torsional displacement of girders, and their strength ensured. 3) Designing the intermediate bracing system (IBS), which based only on the overall stability of bridge structure without caring about the strength of its members, is not enough.

Bridge flutter control using eccentric rotational actuators

An active mass damper system for flutter control of bridges is presented. Flutter stability of bridge structures is improved with the help of eccentric rotational actuators (ERA). By using a bridge girder model that moves in two degrees of freedom and is subjected to wind, the equations of motion of the controlled structure equipped with ERA are established. In order to take structural nonlinearities into consideration, flutter analysis is carried out by numerical simulation scheme based on a 4th-order Runge-Kutta algorithm. An example demonstrates the performance and efficiency of the proposed device. In comparison with known active mass dampers for flutter control, the movable eccentric mass damper and the rotational mass damper, the power demand is significantly reduced. This is of advantage for an implementation of the proposed device in real bridge girders. A preliminary design of a realization of ERA in a bridge girder is presented.

Flutter control effect and mechanism of central-slotting for long-span bridges

The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerody namic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.

A CONSIDERATION ON AERODYNAMIC STABILITY OF BRIDGE STRUCTURES DUE TO ISOLATING DEVICE AT MOVABLE SUPPORTS

A CONSIDERATION ON AERODYNAMIC STABILITY OF BRIDGE STRUCTURES DUE TO ISOLATING DEVICE AT MOVABLE SUPPORTS