Fatigue life assessment method for aged reinforced concrete bridges

Abstract

The invention discloses a method for evaluating the fatigue life of an aged reinforced concrete bridge. The method comprises the following steps of obtaining initial corrosion time of reinforcement in concrete based on the second diffusion law of Fick, and considering the influence of concrete cracking due to corrosion expansion in a corrosion rate model; adopting a small crack growth and near threshold growth analysis and determining relevant parameters of fatigue crack propagation rate of materials by developing a fatigue crack propagation test of reinforced concrete materials; performing a corrosion fatigue test or finite element analysis on corroded reinforcement to obtain stress concentration factors at different corrosion levels, and integrating into a stress intensity factor model to obtain the fatigue crack propagation rate of the reinforcement under the influence of corrosion; comparing the magnitude of a corrosion pit growth rate and the fatigue crack propagation rate and gradually converting into a single growth analysis on fatigue cracks of the reinforcement; meanwhile, combining with vehicle load observing information to realize life evaluation of a bridge at different service stages. The prediction method disclosed by the invention is reasonable and high in popularization, and can provide technical support for evaluating the life of the concrete bridges.

Description

technical field [0001] The invention relates to the field of safety assessment of bridges in service, in particular to a fatigue life assessment method for aging reinforced concrete bridges. Background technique [0002] Reinforced concrete bridges are constantly subjected to repeated vehicle loads during their service. At the same time, steel bars in bridges are prone to corrosion in environments such as deicing salt or coastal environments. Corrosion of reinforcing steel will accelerate the accumulation of fatigue damage and significantly reduce the service life of the structure. With the gradual transformation of structural design theory to make full use of the strength of materials, coupled with the increasing traffic volume and the impact of overloading, the stress range suffered by reinforced concrete bridges will become larger and larger, and the possibility of fatigue damage will greatly increase. Previous studies have shown that the reduction of fatigue life of co...

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Problems solved by technology

The linear damage cumulative damage method is easy to calculate, but it may produce large deviations under random loads, which is difficult to use as a single standard for fatigue life evaluation

Most of the analysis methods based on the theory of fracture mechanics are based on the analysis of the growth of long cracks under uniaxial loading. Existing studies mainly apply this method to pure fatigue analysis without considering the effect of corrosion; another necessary condition of this method is to obtain However, due to the limitation of objective conditions such as material quality, construction level and uneven structure surface, it is very difficult to accurately detect initial cracks.

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