Determination method of non-uniform shrinkage effect of pc box girder section based on equivalent principle

Abstract

The invention discloses a method for determining the non-uniform shrinkage effect of PC box girder section based on the equivalent principle, comprising steps: 1. Division of main beam units to be analyzed: dividing the main beam to be analyzed into N beam units; the main beam to be analyzed is the PC box girder; 2. Equivalent transformation of section uneven shrinkage effect: perform equivalent transformation on the section uneven shrinkage effect of each beam element in the main beam to be analyzed at time t, and obtain the equivalent gradient temperature of each beam element; all The equivalent conversion method of the uneven shrinkage effect of the section of the beam unit is the same; when performing equivalent conversion of the uneven shrinkage effect of each unit, the selection of the section to be analyzed, the calculation of the shrinkage strain of the top plate and the shrinkage strain of the bottom plate, and the calculation of the equivalent gradient temperature . The method of the invention has simple steps, reasonable design and good use effect. The uneven shrinkage effect of the PC box girder section is equivalent to the temperature gradient load of the beam body, which can accurately predict the uneven shrinkage effect of the predicted box girder section and is convenient to realize.

Description

technical field [0001] The invention belongs to the technical field of bridge structure design and construction, and in particular relates to a method for determining the uneven shrinkage effect of a PC box girder section based on an equivalent principle. Background technique [0002] The problem of excessive deformation of long-span prestressed concrete continuous rigid frame bridges has attracted more and more attention from scholars at home and abroad. The researchers mainly used the finite element method to predict and analyze the long-term deflection value and its development trend of continuous rigid frame bridges, but found that the predicted theoretical value was very different from the actual observation value. Not only did the accumulated deflection value of many bridges far exceed the theoretical value The calculation results show that the deflection of the bridge increases rapidly after several years of construction, and there is no sign of convergence. Therefore...

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Problems solved by technology

[0004] Currently commonly used shrinkage and creep prediction models include ACI model (model recommended in ACI 209R-82 specification), CEB-FIP (1990) model, B3 model, GL2000 model, etc. The length ratio is used to calculate the theoretical thickness of the member. In actual calculation, the effective thickness of each part of the box girder is generally averaged, and it is difficult to consider the influence of uneven shrinkage of the box girder section.

Moreover, there is currently no method that can accurately determine the uneven shrinkage effect of the box girder section, and there is no clear implementation method in the finite element predictive analysis

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