Issues of shear deformation measurement in experimental studies

Shear deformation determined using “X configuration method” as traditional instrumentation plan is controversial. Shear deformation of two specimens was re-investigated in this research. One of those (SP3) was representing a RC beam member using a single curvature test scenario and a coupling beam specimen (CB2) was representing a RC beam member using double curvature test scenario. The new instrumentation technology, optical system, provides a useful tool to evaluate different traditional instrumentation plans. Shear deformation is evaluated with different gauge lengths. The best-possible solutions of both specimens are determined using the optical system with the finest grid. Error is estimated by comparing results from “X Configuration” method with the best-possible solution. Analysis results indicate that the smaller gauge length yields the better results. A gauge length of 6.3 in. (160 mm) from X configuration method gives the smallest error, less than 10 %, in measuring shear deformation in a flexural governed member. It suggests that the gauge length to \measure shear deformation in a coupling beam specimen can be limited within 16.5 in. (420 mm). The largest gauge length from X configuration method in measuring shear deformation shows the largest error for both specimen SP3 and specimen CB2.