Engineering Experiments And Investigations On Several Meteorology Issues In Extra Long-span Bridges Building

For the purpose of development of modern large bridges and the demand for establishing bridge design wind parameters and the requirements for meteorological safety controlling in bridge construction, methods to calculate wind parameters in bridge designing and techniques to ensure meteorological safety were studied and were tested in the projects of Sutong Highway Bridge and Qingdao-bay Bridge, based on analysis of the current development and problems worldwide. The main conclusions drawn from this study are as follows:Suitable approaches to calculate wind speed in bridge designing were developed and tested in bridge constructions based on statistics, synoptic meteorology and climatology, and the principle of continuity of mass distribution in hydrodynamics. While providing the bridge designers with wind parameters, this study also solved the problems that wind velocities can not be calculated at bridge locations because of lack of wind velocity data, and that the values obtained from handbooks cannot reflect the characteristics at bridge locations.Considering both the theories of meteorological statistics and the realities in bridge construction, a generalized model of the distribution of extreme values was introduced. The model provides a method to calculate extreme wind speeds under the condition that the real wind velocity will not be exceeded. The subjective determination of the (?)nvelope line? in construction was objectivized. The problems about the probable maladjustment resulted from present criterions using single-extreme distribution model and difficulties to verify the attribution of the distributions of wind speed to a certain distribution function were solved. The engineering risk resulted from subjective determination and sticking on present handbook of wind parameters was reduced.A long time synchronous meteorological observations over water surface, at the riverbank and at the weather stations were conducted, as well as the observations of turbulence characteristics such as wind attack angles. These observations reveal some new observational evidence that are different from the previous theories. These works have a positive effect on determination of wind parameters in bridge designing, and also provide the basic data for correcting the standards and rules.The meso-scale model WRF was used to simulate wind field over broad plain water surface and to test the model(?)ability to reproduce the extreme values of wind speed and the sensitivity of simulation results to parameterizations of various physical processes.A long-distance data transmission technique which combines GPRS and Internet is developed; models for predicting wind over river surface is established; software which combines information collection, transmission and application is developed; a meteorological safety protection system for construction zones is established. All these are proved feasible and effective by operating engineering experiments.Through theoretical studies, observational experiments, numerical simulations and engineering experiments the following conclusions are drawn:(1) Large bias may be resulted if the meteorological data obtained from weather stations or calculated from handbooks are used directly to represent wind parameters at bridge locations.(2) The methods for calculating wind parameters proposed in this study are able to overcome some of the drawbacks existed in the popular methods.(3) Differences may exist between turbulence identities such as wind attack angles and turbulence power spectrum at bridge location and criteria. The differences between wind velocity over water surface and that at riverbank or weather stations are also discriminate from the criterion values. Therefore, the observation experiments are useful to improve the criterion values.(4) The distributing of water and land is the main reason which leads to the differences between the wind velocity over water surface and that at weather stations. The WRF model has a certain degree of ability to simulate the wind velocity at bridge location, but can not be directly used for engineering projects yet.(5) Establishing the system ensuring meteorological security in construction regions can improve the veracity of weather predicting in construction regions and meet the needs of meteorological security information during constructions.