Study On The Elastic Wave Testing Methods For The Anchor Prestressing Of The Precast Beam

With the continuous development and progress of prestress technology,it is widely used in many civil engineering,such as prestressed concrete of bridge,prestressed anchor cable of slope,construction prestress and so on.Therefore,the prestress is closely related to the performance and safety of most civil engineering.Prestress mainly controls the quality of prestressed concrete bridge,and it is a long lifeline for its normal performance.Therefore,the purpose of testing the prestress of prefabricated beams is to detect and evaluate the effective prestress through the construction process and in turn it can guide the level of the prestress construction process by testing the specific data and results obtained.In this way,it can not only control the construction quality of the anchor prestressing of precast beam,but also can avoid applying the unqualified beam into practical engineering.Basing on the analysis of previous detection methods,this paper puts forward the nondestructive testing methods which are based on elastic wave theory to detect the anchor prestressing of precast beam.Comparing to traditional methods,the nondestructive testing methods has the advantages of fast,efficient,economical and reliable.And the indirect economic benefits and social benefits that it brings is very significant.This article mainly carried out the following aspects of the work:(1)This paper illuminates the extensive application of prestressed technology in civil engineering and points out the significance of prestressed precast beam anchor detection under normal use and safety of prestressed concrete bridge.It also points out that the nondestructive testing method based on elastic wave theory is a hot direction detection of current and future of anchor prestressing of precast beam;(2)This paper introduces the development of nondestructive testing technology and the basic properties and propagation characteristics of elastic stress wave in detail,which lays a theoretical foundation for the method of testing anchor prestressing of precast beam.And a theoretical model of vibration frequency,vibration wave velocity and equivalent mass method based on elastic wave theory are established to detect the anchor prestressing of precast beam;(3)Basing on the ABAQUS finite element software,the numerical simulation of the propagation of elastic wave in the stress state is carried out.It is concluded that theelastic wave is feasible to detect the stress and the distribution of the stress in the material;(4)This paper introduces the acquisition and preprocessing of elastic wave signal in prestressing beam anchorage under elastic prestress and describes the time domain analysis and frequency-domain analysis method for elastic wave signal;(5)According to the three theoretical models of prestressing elastic wave detection under prefabricated beam anchors,the laboratory tests are carried out on the vibration frequency method,the vibration wave velocity method and the equivalent mass method.The reliability,validity and accuracy of the test method are proved by the analysis of the experimental data;(6)The detection method based on elastic wave theory is tested in practical engineering application,which proves the reliability,applicability,high-efficiency and accuracy of using elastic wave to detect anchor prestressing of precast beam.It provides a practical and feasible method for fast and efficient test of prestressing force under prefabricated beams.