摘要:

The integrity of internal steel components, whether they be in the form of reinforcing bar mesh, pre-tensioned tendons or post-tensioned cables encased within ducts, is a major factor in determining the useful life of structures built from reinforced and pre-stressed concrete. This article reviews the nondestructive techniques that have been or are being developed which provide information relating to the condition of these steel members, either through direct or indirect measurement. It focuses on the research that has been conducted on true nondestructive methods, giving only brief consideration to electrochemical techniques such as potential mapping, which require at least one-contact point with the steel, and hence removal of some concrete. Testing methods given special attention are those based on the principles of ultrasound, impact echo, acoustic emission, radar and microwave, X-ray and gamma radiography, AC and DC magnetic fields, electrical and optical time domain reflectometry and thermography. The article notes that testing using a particular method can be performed by exploiting different effects, for example ultrasound methods may be based on pulse-echo analysis or frequency response. Hence each section is classified into sub-sections detailing the various processing algorithms employed. Relevant theory, together with key formulae are also included for each technique.

ISSN:1058-9759    

DOI:10.1080/10589759808953058

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This article presents a systematic description of elastic wave parameters in anisotropic austenite. The anisotropy of material is modeled by transversely isotropic media. The equations for the phase and ray velocities of ultrasonic waves are derived on a base of the elastic constants tensor. It is suggested that the waves propagate at an arbitrary angle to the austenitic growth axes. The polarization of elastic waves is calculated.

ISSN:1058-9759    

DOI:10.1080/10589759808953059

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor