Humen Bridge Research Articles

Preliminary Numerical Study on TRID System for Flutter Vibration Control of Bridge Structure

Based on the recently proposed innovative Tuned Rotary Inertia Damper (abbreviated as TRID) control system, the possibility of its application for the wind induced flutter vibration control of long span bridge structure is discussed in this paper. Firstly, the background and current methods for wind induced flutter vibration control of bridge structures are summarized. Then, equations of motion of the bridge segment model are developed based oon the classical Lagrange principle, and the critical wind speed of flutter vibration of Humen Bridge is solved using both Scanlan and state space baased methods. Furthermore, the TRID control system is incorporated into the system model, where the TRID inertia mass can be physically installed between connections of consecutive bridge deck sections. Optimal parameters of TRID control system and their interactions, i.e. tuning frequency ratio, damping ratio and rotary inertia ratio, are analyzed through numerical approaches. Based on thorough numerical analysis, the results show that the TRID control system is feasible and effective on enhancing the flutter vibration stability of long span bridge structures, e.g. the ultimate critical wind speed of the illustration can be increased by 10% at the cost of adding an additional 5% rotary inertia to the bridge structure.

Floor-Beam Web Cutout Shape Analysis to Improve the Fatigue Resistance in Orthotropic Steel Bridge Decks

The modern steel orthotropic decks have been used in steel bridges for 60 years all over the world because of its super structural advantages. Recently, more bridge owners, engineers and researchers pay more attention to the fatigue problem of orthotropic steel decks for a large number of fatigue cracks found in steel bridges. For example, bridge engineers have detected hundreds of fatigue cracks in steel orthotropic deck on the 888-meter long box girder of Humen Bridge only ten years after opening to traffic. How to design or repair the fatigue details in orthotropic steel decks is the critical question to be solved at first step. In current paper, the elaborate numerical analysis model of the orthotropic steel bridge decks was developed using ANSYS software with different floor-beam web cutouts shapes, such as conventional ellipse, circular, trapezoid and Haibach web cutouts. The finite element models were calibrated by static test of one full size orthotropic steel bridge deck model. According to the analysis results, it should select the rational cutout shapes based on actual load and structural conditions in steel bridge deck design and strengthening.

Fatigue Damage Evaluation and Retrofit of Steel Orthotropic Bridge Decks

Since the first application of steel orthotropic deck in bridges, engineers have shown great interest in the popularization of steel decks, based on their various advantages like light-weight, high capacity and so on. However, because of their complex configurations, repeated loading, and stress concentration, many details of steel orthotropic bridge decks are fatigue-sensitive. Recently, considerable increase in traffic volume and wheel loads has caused a number of fatigue cracks in steel orthotropic bridge decks in China. For example, bridge engineers have detected thousands of fatigue cracks in steel orthotropic deck on the main box girder of Humen Bridge only ten years after opening to traffic, which is the first modern suspension bridge with the main span of 888 meters in China. So the bridge owners pay more attention to evaluate the locations of fatigue damages. In current paper, the standard section of the real bridge deck was simulated and a kind of typical fatigue cracks was selected to analyze their fatigue life using S-N curve, the fatigue damage analysis was carried out on the longitudinal ribs to deck plate connections. The fatigue damage analysis results were consistent with the observations from real bridge decks.

Application of the Real-Time Kinematic Global Positioning System in Bridge Safety Monitoring

A real-time kinematic (RTK) global positioning system (GPS) has been developed and installed on the Humen Bridge (China) for on-line monitoring of bridge deck movement, which may occur as a result of seismic activity, traffic load, and such environmental elements as temperature and wind. This paper presents the main features of the on-line GPS RTK system and its value for on-line safety monitoring.

Advanced aerostatic stability analysis of suspension bridges

Aerostatic instability of a suspension bridge may suddenly appears when the deformed shape of the structure produces an increase in the value of the three components of displacement-dependent wind loads distributed in the structure. This paper investigates the aerostatic stability of suspension bridges using an advanced nonlinear method based on the concept of limit point instability. Particular attention is devoted to aerostatic stability analysis of symmetrical suspension bridges. A long-span symmetrical suspension bridge (Hu Men Bridge) with a main span of 888 m is chosen for analysis. It is found that the initial configuration (symmetry or asymmetry) may affect the instability configuration of structure. A finite element software for the nonlinear aerostatic stability analysis of cable-supported bridges (NASAB) is presented and discussed. The aerostatic failure mechanism of suspension bridges is also explained by tracing aerostatic instability path.

TIME–FREQUENCY ANALYSIS OF A SUSPENSION BRIDGE BASED ON GPS

This paper describes the results obtained from full-scale measurements of Humen bridge, which is the second longest suspension bridge in China. A real-time kinematic (RTK) global positioning system (GPS) has been developed and installed on the Humen bridge for on-line monitoring of bridge deck movements. The field wind-induced vibration data were measured by this monitoring system. Three system identification techniques are then adopted in the modal analysis of the wind-induced vibration response: the time–frequency Wigner distribution (WD) technique, the frequency-domain fast Fourier transform (FFT) technique and the time-domain auto-regressive moving average vector (ARMAV) technique. The WD technique can recognize close modal coupling and non-stationary response. The FFT technique can on site verify the quality of the measurements, but its frequency resolution is low and damping estimates are unreliable. The ARMAV method allows for gaining high-frequency resolution. However, it is strictly related to the stationary hypothesis. It is a general conclusion that we can improve the quality of the analysis and get more precise characteristics of the signal by these three methods. In addition, the WD combined with ARMAV seems to be the best case in quantitative analysis of fast-changing vibration signals.

Seismic Analysis of Suspension Bridge Superstructures

Reliable seismic design is necessary for long-span suspension bridges. The dynamic characteristics of long-span suspension bridges are very different from those of short-span bridges. Long-span suspension bridges have basic periods longer than 10 sec, and more than a hundred natural periods closely distributed in the range 0.3 to 5 sec. The present bridge seismic design code in China is not suitable for long-span suspension bridges. Taking the Tsing Ma bridge, Hong Kong, and the Humen bridge as examples, the paper discusses the effects on suspension bridge responses of the response spectrum segments longer than 5 sec, methods of combining the maximum modal responses, the numbers of modes included in mode combinations, the vertical components of earthquake ground acceleration recordings (accelerograms), and the time durations of accelerograms.

The Humen Pearl River Bridge, China

The Humen Bridge across the mouth of the Pearl River is an important link in the expressway network of Guangdong Province in southern China, connecting the Shenzhen and Zhuhai Economic Zones, as well as the rest of the coastal region, with Hong Kong and Macao. The 3618-m-long bridge is divided into five sections: the east approach, the main navigation channel section, the middle approach, an auxiliary navigation channel bridge, and the west approach. Geological conditions at the bridge site are relatively good, with bedrock overlaid by thin soil layers, although conditions differ on each side of the river. Hurricanes are common occurrences, so the design wind speed at the bridge deck level was established at 61 m/s.