Crack identification and detection method for bridge health monitoring

Abstract

The invention discloses a crack identification and detection method for bridge health and safety monitoring. A frequency modulation continuous wave technology of a ground-based SAR is used; an electromagnetic wave signal is transmitted from a radar to the surface of the bridge, the electromagnetic wave signal is reflected back by the surface of the bridge, the electromagnetic wave signal is received, and difference frequency difference processing is carried out on phases of the transmitted and received signals; further denoising and atmospheric correction are performed, and corresponding characteristic point network pixels are processed to form a monitoring point position radar sight line direction deformation graph; error processing and model resolving are performed in the monitoring process, and then a conversion model is constructed to obtain a deformation value in the natural vibration direction of the bridge; a bridge qualitative or quantitative cracking and damage evaluation standard is established in combination with bridge loading deformation characteristics; abrupt change inflection point analysis is carried out by combining a bridge structure and mechanical properties toqualitatively judge whether crack damage and health potential safety hazards exist in the bridge or not. The method is simple and convenient in process, high in monitoring and positioning speed, highin precision, free of direct contact with the bridge, safe and reliable, can replace various sensors such as a standard sensor, a close-range photography sensor and a stress-strain gauge in bridge operation health monitoring, and is obvious in safety and economic benefit.

Description

technical field [0001] The invention belongs to the technical field of civil engineering and surveying and mapping engineering, and in particular relates to a crack identification and detection method for bridge health and safety monitoring. Background technique [0002] Unreasonable design parameters, long-term overloaded transportation, aging, and natural disasters will cause cracking, deformation or even damage to the concrete structure of the bridge, weakening its safety and bearing capacity, and affecting the safety of bridge operation. The vibration amplitude increases in the case of damaged bridge structures, and the damage is exacerbated by static or dynamic loads in the case of multiple damages. Therefore, the detection of damage such as cracks should be strengthened, especially to exclude the occurrence of multiple damages. At present, displacement measurement sensors are the most commonly used method to obtain the deformation of bridge structures. However, bridge...

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Problems solved by technology

At present, displacement measurement sensors are the most commonly used method to obtain the deformation of bridge structures. However, bridges often span rivers, seaways or mountains. It is difficult for existing displacement sensors to accurately reflect the micro-deformation of bridge structures, especially cracks, in an economical, comprehensive and effective way. The development of small deformations is difficult to identify

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