Study On The Statistical Properties And Application Of Vehicle Loads On Freeway

The vehicle load, crowd load, wind load and seismic load,which is introduced in the use process of bridges and freeway structures,is changeable with time.Those loads can be called random load. In exert of random loads, the Failure mechanism of bridges are different from the exertion of other loads. Furthermore, as for random loading, frequency spectrum values (or load spectrum) are requested to be considered. Countries like Britain, America, Germany, and Japan have presented corresponding vehicle load spectrum for fatigue design in the bridge design specifications for each, but we haven't yet. Since bridges and freeways design is based primarily on The Standard vehicle load, which is directly related to the safety and economy of structures, it's meaningful for both science and engineering to formulate a proper vehicle load spectrum. Therefore, this paper focuses on the study of the application and statistical feature of freeway vehicle load. The main points and conclusions are as follows:(1) Data collection of freeway vehicle load. Carry on a field research on one of the single-three-drive freeway in Guangzhou, using ways like manual survey and videoing. Count the monthly traffic flow of the freeway with different periods, lanes and vehicle types and collect the related vehicle load data to get the valueable first-hand material.(2) Two-dimensional vehicle load spectrum statistical analysis. Discuss the statistical features of vary vehicles which travel on specific freeways with time and positions changing. Then probability distribution functions, autocorrelation functions or cross-correlation functions, and power spectral density functions are given to illustrate the statictical features of two-dimensional vehicle load spectrum of freeways.(3) Numerical simulation of two-dimensional random load (vehicle load). Employ the numerical simulation method which is introduced by our discussion group. It's a non-Gaussian process on the basis of skills as distribution conversion. By using this method, the numerical simulation of two-dimensional random load that obeys Weibull distribution is achieved.(4) A method of fatigue test under the two-dimensional random load. In order to work out the test spectrum, transform the two-dimensional random load into single dimensional which is only related to time. The transformation process is based on the damage equivalent principle and influence of excessive or tiny loads is considered. Then the method that realizes the fatigue test of bridge members under two-dimensional random load while using the MTS is proposed.