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Highway bridge structures bear in the process of using the vehicle load, crowd loads, wind loads and seismic loads are time-varying load, to be called the random load. The mechanism of destruction of bridge structures under random loads and other load failure mechanism. Moreover, random load, you need to study the frequency values ??of live load spectrum load spectrum. At present, the United Kingdom, the United States, Germany, Japan and other countries are given in the respective bridge design specifications fatigue design vehicle load spectrum. However, our bridge design specifications have not given load spectrum for fatigue design used vehicles. However, the standard vehicle load is the main basis for highway bridge design, it is directly related to the security and economy of the structure to develop in line with the actual situation of the vehicle load spectrum has important scientific significance and value of engineering applications. Therefore, the statistical characteristics of highway vehicle load and its application discusses. The main contents and conclusions are as follows: (1) highway vehicle load data acquisition. Labor survey, video, and other methods to conduct field research vehicle traffic of a highway (single lane 3) of Guangzhou City, variable to be separately statistics method in accordance with the time, lane, vehicle type (payload) within one month the highway traffic flow statistics, collected the vehicle load data, valuable first-hand information. (2) The statistical analysis of two-dimensional vehicle load spectrum. The passage time of the vehicle, position (lane) as independent variables, respectively, discussed the statistical properties of the various types of vehicles (load) prevailing in said highway, gives them the probability distribution function, the autocorrelation function or cross-correlation function, The power spectral density function, proved the statistical properties of a the freeway two-dimensional vehicle load spectrum. (3) two-dimensional numerical simulation of random load (vehicle load). Our group proposed numerical simulation of non-Gaussian process, based on the distribution of conversion techniques to achieve a two-dimensional numerical simulation of random load spectrum of the Weibull distribution. (4) the the fatigue experimental method in two-dimensional random loads. Based on the the damage equivalence principle, be considered too small, too large load, and two-dimensional random load conversion is the only time-dependent one-dimensional random load to achieve the preparation of the experimental spectrum. On this basis, the proposed method of bridge structural components fatigue experimental use of the MTS assay system to achieve a two-dimensional random loads.
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