Development Of Calibration Device For Reinforcing Layer Thickness Gauge

Reinforced concrete structure with a history of more than 100 years is still widely used,because it can improve the buildings' safety performance against fire,earthquake and other disasters.The concrete layer between reinforced concrete surface and the wall is called steel protective layer,a reasonable control of the thickness of the steel protective layer plays a vital role in the safety of the building,the national standard GB50207-2002 "concrete structure construction quality acceptance norms" clearly defined the thickness of the protective layer as one of the mandatory acceptance test.As a instrument to test the thickness of the steel protective layer,the steel protective layer thickness gauge should have the merits of high precision,easy on-site testing and easy to carry on.However,there are various steel protective layer thickness gauges with different measurement ranges and different precisions in current market.The requirement of the calibration accuracy of the steel protection layer thickness gauge is higher and higher.After a long period of research,the author found that the national metrological departments calibrates the thickness of the protective layer by a standard test piece of cement,which was formed by pouring concrete.While the cement standard test block has the disadvantages of no representative of calibration result,less convenience of maintenance and the origin of value traceability and so on.In order to solve the problems mentioned above,a kind of apparatus for measuring the thickness of reinforcing layer of reinforcing steel bar,which is capable of providing various kinds of reinforcing steel bars,with small thickness error and high automation,is imperative.The study is as follows:(1)A detailed description about the background,significance,current situation and existing problems of the steel protective layer thickness gauge.A brief description of the structure,the detection principle and the calibration principle of the steel protective layer thickness gauge.The author also analyses the key technology of Layer calibration device and offers the sources of the paper.(2)The design of the mechanical system of steel protective layer thickness calibration device,which includes the steel removal device,the protective layer thickness measuring device,the key storage device and other frame designs.The mechanical properties of the mechanical system are analyzed under the theory of the static stress,the static stress of the Doppler and the kinetics of the belt drive of the protective layer measuring device,to eliminate the error brought by mechanical system and prevent electromagnetic interference through the use of non-magnetic materials to.(3)The design of the software system of steel protective layer thickness calibration device.Selecting the Siemens S7-200 PLC circuit,based on the Step7 Micro / Win32 program,choosing the touch screen as the interface,using ADAMS and ANSYS software as the operation interface the calibration performance of the calibration device is analyzed.(4)The dielectric permeability on the steel protective layer thickness calibration device is measured,the repeatability of the calibration device and the stability of the calibration system were experimentally verified.The uncertainty is summarized and the uncertainty analysis of the device is carried out,the value traceability diagram is provided.