Method for testing and evaluating effective prestress of simply supported beam/slab bridge based on beam-slab turnover

Abstract

The invention discloses a method for testing and evaluating the effective prestress of a simply supported beam / slab bridge based on a beam-slab turnover, and belongs to the technical field of bridge engineering structure performance identification and evaluation. According to the method, the characteristics of small dead weight and light weight of the assembly type simply supported beam / plate areutilized, the simply supported prestressed concrete beam / plate is overturned through hoisting equipment, test data in the state before and after overturning are analyzed, coupled dead load effect factors are successfully filtered out from the overall effect, and thus, accurate evaluation of the current effective prestress degree of the simply supported beam / plate is realized. The method has the advantages of low cost, simple equipment, suitability for field application and the like, and is particularly suitable for quickly and accurately testing and evaluating the effective prestress of the assembled simply supported beam / slab bridge.

Description

technical field [0001] The invention belongs to the technical field of bridge engineering performance appraisal and evaluation, and in particular relates to a simply supported beam / slab bridge effective prestress test and evaluation method based on beam-slab overturning. Background technique [0002] For bridges in service without pre-installed prestressed tension sensors, during service due to many factors such as shrinkage and creep of concrete, stress relaxation of steel bars, compression of anchorage ends, slippage of tendons, and friction between tendons and surroundings, etc. The expected loss of prestress will lead to performance problems such as insufficient crack resistance and stiffness degradation of the structure. It is impossible to accurately grasp the current residual level of effective prestress of the bridge, which will bring greater uncertainty to subsequent technical disposal decisions. The technical bottleneck mainly exists in the following two points: (1...

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Problems solved by technology

[0002] For bridges in service without pre-installed prestressed tension sensors, during service due to many factors such as shrinkage and creep of concrete, stress relaxation of steel bars, compression of anchorage ends, slippage of tendons, and friction between tendons and surroundings, etc. The expected loss of prestress will lead to performance problems such as insufficient crack resistance and stiffness degradation of the structure. It is impossible to accurately grasp the current residual level of effective prestress of the bridge, which will bring greater uncertainty to subsequent technical disposal decisions

The technical bottleneck mainly exists in the following two points: (1) In the prestressed beam / slab without initial sensing device, due to the coupling effect of the dead load effect and the prestress effect, it is difficult to know the over-limit prestress that has occurred. The magnitude and distribution of the stress will bring great difficulties to the assessment of the safety of bridge operation in the limit state of normal service; After the defect disease, due to the double nonlinear effect of the nonlinearity of the concrete material and the change of the geometric properties after the section cracks, the generation of over-limit prestress loss is aggravated

However, the analysis of prestress loss based on traditional linear elastic simulation analysis methods and design methods has lost its effectiveness, and the quantitative evaluation of effective prestress under traditional methods cannot be realized; the use of gray theory to predict the loss of prestress or the prediction of effective prestress through artificial neural network models Methods such as prestressing must rely on a large number of on-site measured data and combined with laboratory test results; the method of combining local damage technology with theoretical analysis and calculation can obtain relatively ideal test results, but this technology is a semi-destructive technology. And the workload is heavy, the investment cost is high, and it is not easy to popularize and apply

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