《重庆菜园坝大桥的主桥设计》由会员分享，可在线阅读，更多相关《重庆菜园坝大桥的主桥设计（14页珍藏版）》请在金锄头文库上搜索。
1、112Design of the Main Spans of the Chongqing Caiyanba Bridge重庆菜园坝大桥的主桥设计Man-Chung TANGChairman and Technical Director T.Y. Lin International San Francisco, CA, USA A member of US National Academy of Engineering and a foreign member of Chinese Academy of Engineering. Received Dr.-Ing. in 1955 and has
2、 been designing bridges or 40 years. He is the Technical Director of the Caiyuanba Bridge project.John SUN Associate T.Y. Lin International San Francisco, CA, USA Technical Director T.Y. Lin International (Chongqing) Born in 1963, he received Ph.D from University of California at San Diego, directed
3、 the design of several major bridges and has written a number of technical papers,. He is the Chief Engineer for the Caiyuanba Bridge project.113SummaryThe new Caiyuanba Bridge over the Yangtze River in Chongqing will carry six lanes of highway and two pedestrian walkways on its upper deck as well a
4、s two tracks of monorails on its lower deck. It will serve as one of the transportation backbones for this ever-expanding city, connecting the two busiest business districts of the city: Yuzhong and Nanan. Because the bridge is located at the center of the city and is visible from most parts of the
5、city, aesthetics is a very important matter. After careful study of the location, a slender tied-arch was selected to carry the double level bridge girder over the Yangtze River. Upon completion, its 420-m span will be the worlds longest tied-arch span for combined rail and highway traffic. The side
6、 spans are 102 meters long.Keywords: Bridge, Long span bridge, Arch Bridge1. IntroductionThe mighty Yangtze and its tributary to the north, the Jialing River divide the metropolitan Chongqing into three parts, as shown in the project location map in Figure 1. The Caiyuanba Yangtze River Bridge is a
7、key project connecting segments of the newly planned south-north corridor. Located 1.2 kilometers upstream from the existing “Chongqing First Yangtze River Crossing,” which was built in 1978, the Caiyuanba Yangtze River Bridge is situated in the heart of the town, and will be a vital transportation
8、link for city of Chongqing.The crossing is to carry six lanes of highway on its upper deck and two lanes of monorails on its lower deck. The project consists of a signature tied-arch with the record span of 420 meters, and the south and north approaches the Sujiaba Interchanges connecting the main b
9、ridge to the southern shore, and the Caiyuanba Interchange connecting it to the northern shore.114The final design was completed in November 2003, and official ground-breaking for the project took place on December 28, 2003. When the bridge is completed at the end of 2005, it will be the longest arc
10、h span for combined rail and highway traffics in the world.2. Development of Main Span Structural SystemBecause of its location, the bridge is visible from most parts of the town. Aesthetics is an important factor in the design. The general public of the City prefers an arch bridge. A panel of bridg
11、e experts appointed by the City subsequently accepted the recommendation of the designer, a joint venture of Chongqing Communications Research Institute, Chongqing and T.Y. Lin International, USA to build a half through tied-arch at this location.The Department of Water Transportation determined tha
12、t a bridge at this specific location must provide a minimum navigation clearance of 392 meters. This resulted in a main span of 420 meters.115Figure 1 Project LocationFigure 2 Renderings of the Tied-ArchThe water level of the Yangtze River in the Chongqing area varies significantly seasonally. The d
13、ifference between the high water level and the low water level can be as much as 30 meters. The dry season is from about November to about May each year. During the dry season only a small portion of the river is navigable while in the high water season, the entire riverbed is under water. As a resu
14、lt, the piers of the main span should be sufficiently tall to put the superstructure above the high water level.Most vessels on the Yangtze River are barges carrying cargos with a total weight of up to about 5,000 tons. To resist possible barge collisions, the piers and the lower portions of the arc
15、h rib are made of prestressed concrete.Figure 3 ElevationThe portion of the arch above the deck is a pair of steel boxes. The box section was selected for its slender appearance, which is very important for a centrally located city bridge. The arches are further inclined inwards to achieve a more sl
16、enderappearance. This inclination also improves the stability of the structure. 116Fig. 4 Plan and ElevationThe truss is 11 meters deep to provide sufficient clearance for the monorail, the loading of which is among the highest in the world. To further increase the slender appearance of the structure, the truss is spanning the end spans without intermediate strut supports. This is possible because the 11-meter-deep truss itself has sufficient stiffness to span the 102
