Development of Under–anchorage Effective Prestress Detecting Instrument and Engineering Application

Abstract

For detecting under–anchorage effective prestress of steel strand by lift–off test convenient. Revealing the testing principle of lift–off text and developing the testing in strument. The instrument consists of data acquisition card, oil pressure sensor, high precision displacement sensor and electric oil pump. Based on the graphical software platform LabVIEW, the test program is compiled by using G language. And further gives the program source code. Integrating the texting instrument (LTF 1.0) of under–anchorage effective prestress based on the software and hardware. So the engineering application is carried out. The research results show that the instrument can detect the under-anchorage effective prestress effectively by the load–displacement curve. Meanwhile it has the advantages of high precision, good safety and convenient operation. Through field application, the effective prestress of prestressed steel strand anchor was increased from 54.4% to 94.7%, and same strand dispersion was reduced from 10.2% to 1.7%.