Method for detecting prestress of steel strand under bridge anchor

Abstract

The invention provides a method for detecting the prestress of a steel strand under a bridge anchor. The method comprises the steps: a1, carrying out detection of an anchor head of a steel strand anchorage device through stress wave excitation equipment and stress wave receiving equipment, and enabling the stress wave receiving equipment to receive a sound wave signal; a2, processing the sound wave signal to obtain a spectrogram; a3, fitting the logarithmic normal distribution of a spectrogram to obtain a logarithmic standard deviation sigma of a fitted curve; a4, substituting the logarithm standard deviation sigma into a formula: sigma<t> = [0.867 + 0.113 ln (sigma-0. 044)]*1860 to obtain the prestress sigma t of the steel strand; a5, comparing the prestress sigma t with a prestress design value m of the steel strand, and if sigma<t> is smaller than or equal to m, determining that the prestress of the steel strand is qualified; and if sigma<t> is greater than m, determining that the prestress of the steel strand is unqualified. According to the invention, acoustic characteristic research is directly carried out on the steel strand anchor head; the defect that in the prior art, when a calibration test is conducted on a single steel wire and a whole steel strand, the influence of cement mortar in a corrugated pipe on measurement is not considered is overcome. The error caused bythe adoption of an excitation hammer in an equivalent mass method is reduced; the measurement result is visual and accurate; and the detection method is simple and efficient.

Description

technical field [0001] The invention relates to the field of steel strand prestress detection methods, in particular to a detection method for steel strand prestress under bridge anchorage. Background technique [0002] The tension quality of prestressed steel strands is an important guarantee for prestressed concrete bridges. Excessive prestress will cause fatigue or fracture of the steel strand, which will affect the service life of the steel strand; too small prestress will easily lead to deflection and collapse of the beam body, endangering engineering safety. important. [0003] At present, in the steel strand prestress detection method, the acoustic wave detection method has attracted attention as a measurement method with light equipment, easy excitation and convenient operation. In the prior art, he analyzed the acoustoelastic effect in the single-core wire, and found that this effect is almost linear, so he proposed that the acoustic characteristics of the single-...

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Problems solved by technology

[0004] At present, the acoustic detection method mainly uses the acoustic elasticity theory to directly carry out calibration experiments on the whole steel strand or the single steel wire in the center. However, in actual engineering, the prestressed steel strand is often poured in the corrugated pipe by cement mortar. The method fails to take into account the impact of cement mortar on the measurement results, so the measurement accuracy will be greatly affected when measuring bonded prestressed concrete components

[0005] In addition, the equivalent mass method also uses elastic waves for measurement, which has the advantages of simple equipment and easy operation, but because it uses a vibrating hammer as the excitation source, the elastic waves excited by it have poor stability, so it is easy to cause problems to the measurement results. large error

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