LOCAL BUCKLING OF PULTRUDED FRP BEAMS - ANALYSIS AND DESIGN

An investigation of the local compression flange budding and failure o f pultruded fiber-reinforced plastic (FRP) beams is described in this paper. Results of tests on commercially produced pultruded E-glass/pol yester and E-glass/vinylester composite material wide-flange I-beams a re described. The beams were tested in a four-point bending configurat ion in a specially designed fixture which was designed to cause local buckling and ultimate failure of the compression flange of the beams a nd to avoid global lateral-torsional buckling and local web failure. A ll beams were monitored with strain gages and LVDTs. Buckling loads, f ailure loads, buckling stresses, deflections and failure modes are rep orted. Standard and ''customized'' pultruded beams in the 8 inch (203 mm) series were tested. Based on an analysis of the performance of the standard 8 x 8 x 3/8 in. (203 x 203 x 9.5 mm) beams, two 8 x 8 x 3/8 in. (203 x 203 x 9.5 mm) beams were ''customized.'' In these ''customi zed'' beams the fillet region at the flange and web intersection was a ltered in order to increase its strength and the rotational stiffness. Analysis of the test results of the customized beams indicated that s ignificant increases in load carrying capacity of pultruded beams can be achieved with minor geometry and fiber architecture modifications t o the standard beams. A discussion of the differences in buckling and failure characteristics of the beams based on their resins, sizes, and custom modifications is provided.