外文翻譯--中國(guó)《公路橋梁抗風(fēng)設(shè)計(jì)指南》的幾點(diǎn)說(shuō)明（原文）

1、Journal of Wind Engineering and Industrial Aerodynamics 74—76 (1998) 903—911An introduction to the Chinese wind-resistant design guideline for highway bridgesH.F. Xiang, A.R. Chen*, Z.X. LinWind Tunnel Laboratory, Depart

2、ment of Bridge Engineering, Tongji University, Shanghai 200092, ChinaAbstractSome main comments upon the Chinese Wind Resistant Design Guideline for Highway Bridges are explained. The determination of bridge design wind

3、speeds, the calculation of wind loads including the static part and dynamic part, some empirical formulas for basic frequency estimation of cable-stayed bridges and suspension bridges, critical flutter wind speed estimat

4、ion at the preliminary design stage of bridges and the response spectrum method for estimating the buffeting response of bridges after completion are introduced. ? 1998 Elsevier Science Ltd. All rights reserved.Keywords:

5、 Highway bridge; Wind-resistant design; Guideline1. IntroductionIn the past 20 years, more than 20 cable-stayed bridges with a main span beyond 400 m and several suspension bridges with a span beyond 800 m have been cons

6、tructed in China. At the end of this century in China more long span cable- supported bridges across the sea straits and the Yangtze River will be constructed, some of them are now at the design and planning stage while

7、some are being constructed. Up to now, some wind resistant design guidelines for special bridges have been issued in several countries such as Japan [3], Denmark [6] and Britain [2]. For example, the Wind Resistant Desig

8、n Guideline for Honshu-Shikoku Bridge in Japan [3] and the Wind Resistant Design Guideline for the Great Belt Bridge in Denmark. As the terrain of China is different from these countries, it is necessary for China to hav

9、e her own wind resistant design guideline for bridges.* Corresponding author. E-mail: wtlbed@tju.ihep.ac.cn.0167-6105/98/$19.00 ? 1998 Elsevier Science Ltd. All rights reserved. PII: S 0 1 6 7 - 6 1 0 5 ( 9 8 ) 0 0 0 8 2

10、 - 8meteorological station in the area where the bridge will be constructed. The terrain type is cataloged as Type II.2.2. Bridge standard design wind speedThe bridge standard design wind speed is the 10 min average wind

11、 speed at the height of the bridge decks. It depends on the terrain type of the bridge site and height of the bridge deck above ground or water. In the Guideline, 4 types of terrain are cataloged and the wind speed verti

12、cal profile is assumed to be in accordance with the exponential law. For terrain Types I, II, III, IV, exponential indexes ? are respectively 0.12, 0.16, 0.22, 0.30 and roughness heights z? are respectively 0.01, 0.05, 0

13、.30 and 1.0 m. The bridge standard design wind speed º? can be obtained byº?“K?º?? (1)in which K? is a factor depending on the terrain type of the bridge site and the height of the bridge deck above ground

14、 or water.2.3. Gusty wind speedThe gusty wind speed can be obtained fromº?“G?º? (2)in which G? is the gusty wind speed factor. Based on the method developed by Solari [9], the gusty wind speed factor was calcul

15、ated for the 4 terrain types defined in the Guideline by using Kaimal’s spectrum [12]. The values are given under the condition of wind speed º“40 m/s and z“40 m, the height of a bridge deck above the ground or wate

16、r. For terrain Types I and II G?“1.38; but for Types III and IV, G?“1.70. The gusty wind speed can be used for estimating wind loads of short span bridges or long-span bridges at their preliminary design stage.2.4. Flutt

17、er checking wind speedThe code for the allowable wind speed against flutter instability takes the same form established by the Honshu—Shikoku Bridge Authority in 1976:º??*[º??]“1.2??º?; in the range of !3&

18、#176;(?(#3° (3)in which º?? is the critical flutter wind speed of bridges obtained from wind tunnel tests or theoretical calculations; and ? is the attack angle of the air flow. The coefficient 1.2 is a princip

19、al safety factor considering reliability of experimental testing, design and construction of structures, social importance of structures and a destruc- tive feature of the flutter instability. The coefficient ?? is a con

20、ditional safety factor considering spatial gusty wind speed fluctuation. To cover all cataloged terrain types, the coefficient ?? is calculated for 4 terrain types by using Kaimal’s horizontal spectrum instead of Hino’s