Method for detecting bearing capacity of medium and small span prestressed concrete beam bridge after fire

Abstract

The invention belongs to the technical field of bridge detection, and particularly relates to a method for detecting the bearing capacity of a medium and small span prestressed concrete beam bridge after fire, which comprises the following specific steps of: dividing and numbering detection areas; actual measurement values of five types of evaluation indexes including concrete colors, rebound values, hammering reactions, fire cracks, concrete falling areas and depths in all the measurement areas are obtained; calculating damage scales of the five types of evaluation indexes according to a testarea damage level identification rating table, and taking a highest value as a comprehensive scale Di of the test area; calculating the weight i of each measurement area; taking a weighted average value of the comprehensive scales of all the measuring areas of each beam as a fire comprehensive damage scale Z of the beam; and determining the reduction rate of the bearing capacity after fire according to the interval of Z. The complex finite element calculation method avoiding excessive fire is used for quickly and quantitatively obtaining the limit bearing capacity reduction rate of the structure, is easy to implement, high in feasibility and high in result reliability, and provides reference for obtaining the residual bearing capacity, re-assessing whether the structure needs to be repaired, reinforced and re-put into use or disassembling and rebuilding.

Description

technical field [0001] The invention belongs to the technical field of bridge detection, in particular to the technical field of reinforced concrete damage detection, and specifically relates to a method for detecting the carrying capacity of prestressed concrete girder bridges with small and medium spans after fire. Background technique [0002] Expressways are the lifeblood of regional economic development, and bridges, as an important connection line for expressways across rivers and canyons, play a huge role in shortening transportation distances. Due to the surge in highway traffic and oil and gas resources transportation, the frequency of fires caused by traffic accidents is increasing, which brings great harm to the safety of bridge structures. As the most widely used building structure material today—reinforced concrete will undergo a series of physical and chemical changes when subjected to fire. With the prolongation of the fire time of the bridge, the yield stres...

AI Technical Summary

Problems solved by technology

[0005] Existing methods mainly use the finite element method with a huge amount of calculation to obtain relatively accurate results. Due to the different geometrical section types and fire exposure methods of prestressed concrete members, and the material properties and mechanical properties in the section are non-uniform, this makes After each bridge has passed through the fire, it needs to be inspected on site and then remodeled. The damage degree and remaining bearing capacity of the bridge cannot be quickly obtained, and there is a danger of secondary collapse, which will bring inconvenience to rescuers.

Moreover, the existing detection methods lack quantitative evaluation of the ultimate bearing capacity of prestressed concrete structures after fire, and the ultimate bearing capacity is an important indicator to re-evaluate whether the bridge needs to be repaired and strengthened to be put into use again, or an important basis for demolition and reconstruction.

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