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| Research on the Forming Mechanism of Cracks of Prestressed Concrete T Beam in Cold Area |
| XIANG Min1，FENG Yang - yang1，ZHANG Yan - mei2 |
| (1. Shijiazhuang Tiedao University， Shijiazhuang，Hebei 050043，China; 2. Hebei Reach Traffic Engineering Consulting Co. Ltd，Shijiazhuang，Hebei 050021，China) |
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Abstract Research purposes ： A wide range of cracks are shown in the prefabricated prestressed concrete T beam on a highway located in the cold northern area which is still in construction stage，which is longitudinal cracks along the longitudinal direction of the prestressed pipe. In order to study the forming mechanism of cracks， through site investigation，T beam analysis and measurement test and the explosion test of prestressed pipe injection， this paper deduced prestressed pipeline lateral concrete stress field and displacement field analytic expression caused by prestressed concrete structure prestressed pipe concrete slurry and ice frost heave by using lame solution and higher concrete theory， analyzed the stress field distribution of prestressed pipe deviation which may occur in the construction of T beams by using the finite element，and analyzed the existing state of beam section stress field in situation of porous prestressed pipe concrete slurry and ice frost heave. Research conclusions ：( 1 ) Crack formation mechanism ： The grouting slurry is poor in quality ； the construction technology can;t meet the requirements, free water and air exist in prestressed pipes, when the temperature drops to minus ； frost heave static detonation caused by grouting slurry and free water leads to stress field change of prestressed pipe and concrete out of pipe and tensile stress higher than tensile strength of concrete ； so the concrete in and out of the beam cracking and freezing and thawing cycles appears, liquid in the pipe will flowout along the different crack path. (2) The prestressed reinforcement concentrates in the central section of beam where prestressed pipe concrete cover of horseshoe and web is thinner，static detonation frost heave can easily cause the superposition of concrete tensile stress in this section, leading to concrete cracking of prestressed pipe，all directions in horseshoe and web plate in that section. (3 ) Beam body in which cracks appear will significantly affect the bearing capacity and durability，and it is difficult to asess the impact. (4) The research result can provi(ie reference for disease control of similar engneering.
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Received: 27 October 2015
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2016, Vol. 33 
