The Disease Mechanism Analysis And Durability Evaluation Of Concrete Beam Bridges In Arid And Cold Region

With the vigorous development of highway transportation in C hina,bridge,as an important transportation facility,plays an irreplaceable role.However,a large number of bridges have been affected by environmental changes,increased traffic loads and deterioration of their own materials,and developed disease of various degrees.Especially in the northwest of China,due to the bad weather,such as dry,cold and strong ultraviolet rays,the performance of the bridge structure to resist natural deterioration and corrosion is weakened,the bearing capacity is reduced,and the applicability and safety of the bridge structure are not satisfied.It seriously affects the durability of bridges during their design life and poses a great threat to people's safe travel.Therefore,it is urgent to study the durability of concrete bridges in dry and cold areas.Taking the concrete beam bridge in the northwest dry-cold area as the research object,This paper investigates the damage of the beam bridge on the trunk highway,and deeply analyzes the influence of the climate environment and the traffic load on the durability of the concrete beam bridge in this area.150 girder bridges are selected as samples for disease statistics.The disease degree of these girder bridges is analyzed to conform to normal distribution,then the normal distribution is verified by the mathematical statistical methods such as skew degree,peak value test and so on.It is proved that the overall disease degree of the beam bridge is approximately obey to normal distribution.On this basis,the mechanism of the main diseases affecting the durability of concrete beam bridges is analyzed.This paper studies the theory of durability evaluation of concrete bridges,and makes a comparative on the comprehensive evaluation methods of durability;and analyzes the applicability of unascertained measure theory to durability evaluation of concrete beam bridge and expounds the theory of unascertained measure in detail.The durability evaluation index system of concrete beamr bridge is constructed for the regional environmental characteristics in dry-cold areas and the evaluation index is quantified.The durability evaluation grade and the evaluation criteria of each index are determined by referring to the relevant standards and specifications,.On the basis of the entropy weight method and unascertained measure theory,the durability evaluation model of concrete beam bridge in dry-cold area is constructed,namely,constructing the unascertained measure function of single index,determining the index weight by entropy weight method,analyzing the multi-index unascertained measure vector according to the confidence recognition criterion.The durability state of multiple bridges is sorted by examples,and the validity and maneuverability of the model are verified.And it is helpful for bridge managers to clearly grasp the durability status of the full-line beam bridge,arrange the maintenance resources rationally,and provides suggestions for the decision of bridge durability maintenance,so as to improve the utilization efficiency of bridge maintenance funds.Therefore,the durability assessment of concrete beam bridge in dry-cold areas is not only of practical significance to the scientific management of the existing bridges,but also of great significance to the design of durability of bridges to be built.