| As one of the important indicators of bridge design,automobile load effect is an important basis for the evaluation of the proposed bridge load value and the existing bridge safety.It has received extensive attention and research.Based on the Shuangbu North overpass in Qingdao area,this paper makes a statistical analysis of the vehicle load characteristics on the bridge.The MATLAB software is used to realize the vehicle load flow simulation and the influence line loading calculation,and the urban bridges in this area are loaded and congested.The load effect of the operating state.The load equivalent principle is used to determine the uniform load concentration qk and the concentrated force load pk in the corresponding vehicle load.Proposed reasonable amendments to the values of the vehicle load for the specification and new bridge construction.The main research contents are as follows:(1)The relevant theories used in the analysis of vehicle loads and their effects are described in detail.This paper introduces the commonly used numerical features of random variables and several commonly used definitions of probability distributions.It also gives a brief description of the estimation of each parameter of the distribution and the method of hypothesis testing.In order to study the variation of random variables over a long period of time,time is introduced.Factor t applies a stochastic process theory that better reflects objective reality.(2)Based on the Shuangbu North Overpass in Qingdao area,the data survey was carried out,and the corresponding survey implementation plan was formulated.The traffic flow data of various models were obtained through manual site survey and video surveillance,and the factory information of various models was combined(front suspension,rear Suspension,wheelbase and axle weight distribution ratio coefficient)7 kinds of vehicle load models suitable for the region were obtained;statistical analysis of vehicle weight information for various models;in order to study the overload conditions of various models,this paper combines relevant The over-load overload specification carries out overload analysis on the vehicle weight data.The results show that there are different levels of over-load overload conditions in various models;combined with the vehicle load-related data obtained from the survey,the Monte Carlo method is used to generate the actual traffic characteristics.The random vehicle load flow in the intensive operation state and the congested operation state provides a basis for the calculation of the vehicle load effect.(3)The MATLAB program is used to calculate the influence line load of the research object,and the vehicle load effect value under different operating conditions is obtained.The analysis results show that under the action of the actual fleet,the maximum effect of the simply supported beam and the continuous beam varies with the span.The ratios of the norms also exhibit different characteristics: the maximum value of the mid-positive moment effect of the simply supported beam is up to 1.34,and the maximum value of the negative moment of the continuous beam bridge is up to 1.54.(4)In order to reduce the influence of the tail data on the extremum extrapolation results,the tail data of the GPD distribution fitting effect value is used in this paper,and the POT model is obtained.The extreme value extrapolation theory is used to obtain the standard value of the load effect in different design reference periods.In the dense and congested state,the standard value of the full-span simple-supported beam spanning positive moment is greater than the standard value corresponding to the city-A level from T=10 years;except for the range of 10?25m in the dense operation state In the internal and congested operation state,the standard values in each design reference period within the range of 10?20m are smaller than the highway-I value,and the other values are greater than the highway-I value.The maximum effect standard value of the negative bending moment of the continuous beam fulcrum of each span with different spans is greater than the urban-A and highway-I specification values from T=10 years.(5)According to the design load standards at home and abroad,the lane load has become a common vehicle load mode in various countries.According to the effect standard value obtained in the fourth chapter,according to the internal force equation of simply supported beam,the L-pk maps with different loading bases are obtained,and the uniform load qk of the equivalent lane load is determined to be 19.9 k N/m.When the calculated span L is less than 15 m,pk is a fixed value of 177.77 k N;when the calculated span L is greater than or equal to 15 m and less than or equal to 45 m,pk is determined by the formula(3.5L(10)125.27);when the calculated span L is greater than 45 m,pk is a fixed value 265 k N.This provides a reference for the development of design load standards for urban bridges in the future. |
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