Research On Applicable Type Of Concrete Bridges Based On The Cracks

Reinforced concrete structure, with its carrying capacity, good temperature tolerance performance, low cost of building and being able to bring the high tensile strength of steel and compressive strength of concrete into play, can be used extensively in engineering. However, the phenomena of disease (such as crack etc) happened prematurely, structural damage and even collapse are present in all built bridges.To prevent or alleviate such problems, modern bridge constructions are more take the action of late remedy. Yet such remedial measures cannot radically solve the problem of disease occur frequently, and that the disease like crack cannot be avoided simply though increasing material quality and improving the construction technique, it has a very tight connection to structure types, structure stress condition. Therefore, we must choose reasonable design contributes as much as possible to avoid or delay the emergency of diseases in the design stage, thus improving the durability of the bridge structure, and extend the bridge life.At first, this paper takes the cracking mechanism as the starting point, introducing the common forms and reasons of structural cracks and non-structural cracks in particular. And conclude that the beam or slab cracking is the most common adverse effects in all bridge deteriorations, decided to form the kinds of diseases as the main contents of this article.Then starting from the importance of bridge assessment, this paper introduce the crack evaluation index of bridge assessment, and analyze and summarize the practical significance and feasibility of taking the crack evaluation index as the main reason of bridge type selection. On this basis, the paper analyze the bridge structure factors and sensitive properties which affect the crack state, and obtain the sensitive factors of bridge structure which is related to crack evaluation index. Besides, according to regressively analyze the crack data which is obtained from the 64 bridges, we conclude the crack parameter distribution curves which are changed with span for various bridges. Then we categorize the 64 bridges by bridge structure sensitive factors, and find out the distribution of crack parameter distribution curves which are changed with span of same kind bridges. Finally, the crack parameter distribution curves which are changed with span are analysed. Putting together all the crack date of bridges which have the same sensitive factors and the distribution of crack parameter distribution curves changed with span, and then do the work of regression, so we can explore the envelope curves and those general formulas of the max crack width and the relative seam length which are changed with span under the specific structure forms. Based on the above analysis, the rules that based on crack parameter for select bridge structural style are obtained.