外文翻譯--車輛與大跨度箱梁橋動力相互作用的計(jì)算機(jī)模擬（原文）

1、TSINGHUA SCIENCE AND TECHNOLOGY ISSN 1007-0214 12/67 pp71-77 Volume 13, Number S1, October 2008 Computer Simulation of Dynamic Interactions Between Vehicle and Long Span Box Girder Bridges Lei Gong, Moe S. Cheung** De

2、partment of Civil Engineering, University of Ottawa, Ottawa, ON, K1N 6N5, Canada Abstract: Moving vehicle loads, associated with roadway traffic can induce significant dynamic effects on the structural behaviours of brid

3、ges, especially for long-span bridges. The main objective of current research is to study traffic induced dynamic responses of long-span box-girder bridges. The finite element method has been employed in this study to ob

4、tain a three-dimensional mathematical model for the bridge system. For vehicle-bridge dynamic interaction analysis, the vehicle is modeled as a more realistic three-axle, six-wheel system, and the corresponding dynamic i

5、nteraction equations have been derived. The bridge-vehicle inter-action is affected by many factors. The current study has been focused on such factors as: vehicle speed, vehicle damping ratio, multiple traffic lanes, ma

6、ss ratio of vehicle and bridge, and dynamic characteristics of bridge. Case studies have been conducted to investigate these factors by using several box girder bridge examples including Confederation Bridge, the longest

7、 box girder bridge in the world. Key words: vibration; box girder bridge; long-span; bridge-vehicle interaction; finite element analysis Introduction Box-girder and deck type bridges have been proven to be very efficie

8、nt structural forms for medium to long-span bridges. These bridges normally consist of inter-connected plate elements of either prestressed or rein-forced concrete, or structural steel, or a combination of them, which pr

9、ovide sufficient flexural and torsional strength to resist applied loads. Box-girder bridges are usually aesthetically pleasing and can be easily con-structed to follow any required alignment in plan and require relative

10、ly small amount of maintenance. Box-girder bridges tend to be slender and more flexible than other types of bridges. Therefore, atten-tion must be paid to the avoidance of excessive accel-eration and dynamic deflections,

11、 which may cause pe-destrian’s discomfort and concern. Usually, dynamic deflections are more pronounced in bridges with tor-sional dominant modes, especially at sidewalk locations. Such modes tend to have more detrime

12、ntal effects on human responses to vibrations and comfort level of pedestrians using the bridge[1]. The acceleration level of a bridge is also directly related to the governing vi-bration mode. Since acceleration has a s

13、ignificant ef-fect on human sensation and pedestrian comfort, the torsional mode must be avoided at all costs. In recent years, considerable efforts have been made in order to better understand the dynamic behavior of bo

14、x girder bridges with traffic loads. In the previous studies, the vehicle has usually been modeled as: mov-ing load, moving mass or sprung mass. Only a few re-searchers have adopted 3D vehicle model. Most of the previous

15、 studies focus on short to medium span box girder bridges, and little information is available for long-span box girder bridges. Some of the key parame-ters such as vehicle speed and dynamic properties of bridge have inv

16、estigated previously; however, very Received: 2008-05-30 ** To whom correspondence should be addressed. E-mail: mscheung@ust.hk; Tel: 852-23587125 Lei Gong et al：Computer Simulation of Dynamic Interactions Between Vehic

17、le ... 73attached to the three axles. The trailer with concen-trated mass m2 is pin connected to the tractor with con-centrated mass m1 at point D. The dash-pots provide viscous damping. The mass of the axles, wheels, d

18、riveshaft, brakes, and the suspension system is sup-ported by the wheels, which always remain in contact with the bridge surface. Fig. 3 Vehicle model There are five independent degrees of freedom (d.o.f.) in the vehicle

19、 system, namely, translation dz1, rotation θx1 and rotation θy1 of sprung mass m1, and translation dz2 and rotation θx2 of the sprung mass m2 with respect to the longitudinal axis x along the direc-tion of motion, the tr

20、ansverse axis y, and the vertical axis z. The rotation about y of mass m2, θy2, is related to the above five independent d.o.f. The unsprung mass m3, m4, and m5 are assumed to be concentrated at the centers of the three

21、 axles, re-spectively. Mass m3 can undergo vertical translation dz3 and a rotation θx3. Similarly, mass m4 has vertical trans-lation dz4 and a rotation θx4 and mass m5 has vertical translation dz5 and a rotation θx5. Sin

22、ce mass m3, m4 and m5 are not supported by springs and the wheels are summed to remain in contact with the bridge surface, dz3, θx3, dz4, θx4, dz5, and θx5 are not independent but re-lated to the vertical motions of the

23、contact points be-tween the wheels and the bridge surface. Thus, the to-tal number of d.o.f. of the bridge-vehicle system is N + 5, in which N is the number of d.o.f. of the bridge structure. For numerical analysis, the

24、 physical properties of the vehicle model are described in Table 1. Table 1 Physical properties of vehicle Mass (kg) Mass moment inertia (kg·m2) Axle stiffness (N/m) m1 28 038 Ix1 23 448 k1 1 138 300m2 2804 Iy

25、1 263 052 k2 1 138 300m3 1752 Ix2 4982 k3 1 138 300m4 1402 Iy2 26 305 m5 1051 Ix3 4982 Ix4 879 Ix5 879 3 Free Vibration Analysis The dynamic characteristics of a box-girder bridge, in-cluding its natural frequencies

26、, vibration mode shapes, and mechanical damping properties’ are important fac-tors which can significantly affect its stability behavior under traffic loads[3]. Aspect ratio defined as the ratio of the length of a bridge

27、 deck to its width is a key pa-rameter than influences the natural frequencies and mode shapes. In this study, the aspect ratio of Bridge A varies from 2 to 4, corresponding to spans of 18.7 m, 28.05 m, and 37.4 m. The a