Research On The Measurement Of Strain In The Reinforced Concrete Bridge Loading Test

The resistance strain gage is often used to get the strain in the loading test ofreinforced concrete bridges.But,when there are some cracks on the concrete,in ord-er to avoid the interferences to the results of the strain test, the concrete protecti-ve layer has to be chiseled.Then paste the resistance strain gage on the steel afte-r the steel polished. But this process will destroy the structural integrity,with heav-y workload incresed.This thesisc uses the tool-type strain gauge and the resistance strain gage toget the strain of three different structures, which are steel beam, reinforced beamand real bridge,and then analyzes the data of the experiments.Research has revealed that two kinds of strain gauge get some similar data inthe steel beam loading test and real bridge loading test, and the relative deviatio-n of the two sets of data is around2%. In the reinforced beam loading test,the t-ool-type strain gauge can refIect the strain variations of the structure when there i-s no crack on the concrete. This article focuses on whether the tool-type strain g-auge can get the real stress of the structure when cracks appear.When cracks app-ear,the common way is to paste the resistance strain gage on the steel arrangedin the concrete. Differently,the tool-type strain gauge which has been chosen in thi-s article without damaging the concrete beam also can complete the strain measur-ement by crossing the cracks.The results of the loading tests show that the tool-t-ype strain gauge can be used in cracked-beam’s loading tests when the width of t-he crack is under0.1mm. In this case,the data which obtained by the tool-type st-rain gauge can reflect the real structural distortion. The relative deviation of the t-wo sets of data obtained by tool-type strain gauge and resistance strain gage isaround5%.Preliminary study suggests that:In the loading test of reinforced concrete bridge-s, pasting the tool-type strain gauge on concrete surface to get the strain values i-s feasible, with the advantages of no damage to structure and fast installation,etc.