Abstract
This paper presents a method and procedure of sensing and determining critical shear buckling load and corresponding deformations of a comparably large composite I-section using strain rosettes and displacement sensors. The tested specimen was a pultruded composite beam made of vinyl ester resin, E-glass and carbon fibers. Various coupon tests were performed before the shear buckling test to obtain fundamental material properties of the I-section. In order to sensitively detect shear buckling of the tested I-section, twenty strain rosettes and eight displacement sensors were applied and attached on the web and flange surfaces. An asymmetric four-point bending loading scheme was utilized for the test. The loading scheme resulted a high shear and almost zero moment condition at the center of the web panel. The web shear buckling load was determined after analyzing the obtained test data from strain rosettes and displacement sensors. Finite element analysis was also performed to verify the experimental results and to support the discussed experimental approach.
Highlights
An I-section beam consists of two panels of flanges and a web panel
The I-sections are subjected to combined axial and shear stress fields. It is well-known that the web panel does most of work in resisting the shear force [1,2]
The experimental buckling load was estimated from the load-lateral displacement curves obtained from the displacement sensors (Figure 10) and from the load-strain relation curves determined by the data points of strain rosettes (Figures 11–13)
Summary
An I-section beam consists of two panels of flanges and a web panel. When loaded, the I-sections are subjected to combined axial (or normal) and shear stress fields. Bank [4] and his colleagues published a paper describing their effective lateral buckling test method for composite beams. In 2002, Roberts [5] published that a shear deformation could significantly influence the buckling behavior of a composite I-section under any loading scheme. A full experimental approach to obtain the shear buckling load of large polymer composite I-sections has not been studied much yet. This is because a pure shear stress state is very difficult to achieve experimentally with a large span composite I-section. A test method to detect and determine the critical shear buckling load and to observe the buckling behaviors of a comparably large pultruded composite I-section was discussed. The results from the FEA were compared with those from the experimental test to verify and support the discussed experimental method
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