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This seven and one half mile corridor sees a daily traffic volume of over one hundred and ninety five thousand cars. With this much traffic volume in such a short stretch of road, it was no surprise that excruciatingly lengthy bottle necks are a daily occurrence. A visit to the D.C./Virginia/Maryland region, and you'll see just why it was time for some major road/bridge improvements in one of the worst bottle necking stretches of road in the country.
Shin, Jong Hyun (Institute of Construction Technology, Engineering and Construction Group Samsung C&T Corporation) | Park, Hyun Il (Institute of Construction Technology, Engineering and Construction Group Samsung C&T Corporation)
Local scour refers to the loss of bed materials around the foundation of a bridge by flow change, when structures are built in the water. Local scour depths are usually determined using empirical formulas, and field monitoring is conducted in the construction stage to verify the estimated results. However, in an offshore environment, it is difficult to acquire scour data due to tide and waves. In this study, a 3D scour monitoring system was developed to measure scour contour for sea-crossing bridge piers. The developed 3D scour monitoring system consists of profiling sonar, a rotating driver, and a compact data logger. In the verification test, the water depths measured by the system agreed well with the plumbed depths. For field application, the 3D monitoring system was applied at one main pier of the Incheon Bridge in the Republic of Korea. The results show that this system can effectively measure the real maximum scour depth and the extent of scour around the sea-crossing bridge pier.
Local scour around bridge piers is one of the major causes of bridge failures. Evaluation of local scour depths has been undertaken by many researchers in the last several decades. For non-cohesive soils, some empirical equations have been extensively used (e.g.: Laursen, 1962; Neill, 1964; Melville and Sutherland, 1988; Richardson and Davis, 2001). On the other hand, a few researchers have been conducted on cohesive soils. Gudavalli (1997) showed that the cohesiveness of soils has no noticeable influence on the maximum scour depth. This indicates the equations given for non-cohesive soils can be applied to piers on cohesive soils. In an offshore environment, bridge piers are influenced by a tidal current and waves. Sumer and Fredsøe (2002) have presented results for equilibrium scour depth under the combination of current and waves.
Figure 1 Long term monitoring results To mitigate the VIV of 2 nd Jindo Grand Bridge, multi-tuned mass damper(MTMD) installed inside the stiffening girder in 2012. MTMD is composed of 4 light massed tuned mass dampers. Each TMD is tuned the first bending frequency to mitigate VIV. After installation of MTMD, significant vibration was not observed as shown in Figure 1. In Figure 1, the value of exceeding 50 cm/s 2 is the buffeting responses.
Gan, Langxiong (School of Navigaiton, Wuhan University of Technology) | Zhang, Heng (School of Navigaiton, Wuhan University of Technology) | Wen, Yuanqiao (School of Navigaiton, Wuhan University of Technology) | Zou, Zaojian (School of Naval Architecture, Shanghai Jiao Tong University)
Pan, Jin (Wuhan University of Technology) | Wang, Yong (Wuhan University of Technology) | Huang, Shiwen (Wuhan University of Technology) | Xu, Mingcai (Huangzhong University of Science&Technology, Wuhan University of Technology)
In the calculation of the forces between ship-bridge impacts, the influential parameters are needed to be identified. Based on the AIS (Automatic Identification System) analysis on vessel transit path of the bridges over Yangtze River, the influential parameters of the ship- bridge collision of transiting vessel are investigated. These influential parameters include the ship sailing information and static information, namely yaw angle, velocity, tonnage and the track of ships. For the correctness of probabilistic distributions of these parameters, the chi- square test is applied to modify the probabilistic distributions. The aberrancy angle and vessel velocity probabilistic models related with impact forces are established and also verified by goodness of fit test.
With the development of economy and technology, bridge construction has entered a new period. At the same time, marine transportation has been also developed; the velocity and tonnage of ship are increasing, and the navigational density of channel through bridges become larger. These aspects would increase the probability of ship-bridge collision. Hence, the risk assessment of ship-bridge collision for the safety of designed bridge is needed to be carried out to evaluate whether design of the bridge meets the safety requirement for anti-collision. The influential parameters of ship-bridge collision include the span arrangement of the bridge, track distribution, yaw angle, velocity, impact angle, displacement and the impact position of ships crossing bridge.
Many researchers have studied probabilistic risk for ship-bridge collision(e.g. Samuelides et al., 2008; Goerlandt et al., 2012). Traditional risk analyses of ship collision generally calculate the possibility of ship-bridge collision with empirical formula, which may be not appropriate to describe every scenario of the studied areas. The probability of collision and consequences are determined based on the traffic conditions, namely the actual information of vessels, such as the velocity, displacement and orientation. Nowadays, the normal distribution is often used to describe these influence parameters of ship- bridge collision (Dai, 2002). It was found that the impact scenario models have significant effect on the collapse probabilities of bridge (Kaarle et al., 2013). No well justified impact scenario models are available for every investigated area by now. The adequacy of currently available models for impact scenarios should be improved based on actual data, i.e. models linking the traffic conditions to the conditions at the moment of collision.