A Stress Correction Method for Main Girder of Long-span Prestressed Concrete Cantilever Construction Bridge

Abstract

The invention relates to a method for correcting a main girder stress of a large-span prestressed concrete cantilever construction bridge. In a creep strain calculation method considering a section construction characteristic of the large-span bridge, a time-varying elastic modulus and an equivalent elastic modulus between any two age periods are introduced; non-stress strain generated by creep is more accurately removed; and a corresponding secondary development technology is selected for performing secondary development on MATLAB, so that parametric interface operation is realized. The method comprises the following steps of Step 1: calculating a strain value caused by concrete creep; Step 2: calculating the influence of the time-varying elastic modulus on strain correction; Step 3: calculating a strain value caused by a temperature difference; Step 4: calculating a strain value caused by concrete shrinkage; and Step 5: based on secondary development of a MATLAB platform, compiling a main girder stress correction calculation program, and performing calculation. According to the method, the real main girder stress in the bridge construction process can be accurately calculated; the stress calculation and analysis efficiency in construction control can be improved; and the development of a large-span bridge construction control technology can be better served.

Description

technical field [0001] The invention relates to a method for correcting the stress of a main girder of a large-span prestressed concrete cantilever construction bridge by expanding the head of a perforated steel pipe by using expansive cement, and belongs to the field of civil engineering test devices. Background technique [0002] Long-span prestressed concrete bridges, such as continuous girder bridges and continuous rigid frame bridges, are often constructed in sections using cantilever. During construction, the stress of each beam section must be measured and controlled in order to accurately guide the construction of the next stage. Since the bridge before closing is in the shape of a cantilever with no constraints at both ends, under the influence of temperature changes and concrete shrinkage and creep, the free expansion and contraction of the beam body will produce stress-free strain, so the measured stress value of the main beam needs to be corrected and calculated. ...

AI Technical Summary

Problems solved by technology

However, the above-mentioned measured strain correction method first ignores the influence of gradual application of load on creep during segmental cantilever construction of long-span girder bridges, and secondly does not consider the characteristics of concrete elastic modulus with age development, which will lead to the corrected stress value There is still a large gap with the theoretical value, and it cannot accurately reflect the real stress state of the structure during the construction process, which is not conducive to effective and accurate bridge construction control.

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