COMPRESSION CREEP OF PULTRUDED E-GLASS-REINFORCED-PLASTIC ANGLES

Results from an experimental investigation of the compression-creep be havior of thermoset-pultruded fiberglass-reinforced-plastic angle sect ions are presented. Tests were carried out on three 152 mm (6 in.) ang le stubs made of isophtalic polyester resin with 53-59% E-glass fibers in weight. Each stub was instrumented with twelve 5-mm-long gauges in order to assess the variability of the strain measurements on the fac es of the shape. Coupon-creep and stub tests were carried out simultan eously, and results of the two series of tests were compared to valida te the use of coupon tests to predict creep deformations of full-sized members. The total duration of the tests was 2,500 h in creep and 250 h in creep recovery. Average predictions using Findley's power law wi th creep parameters determined from the stub tests and coupon tests ag ree with one another and with the actual creep strain measurements on the stubs. This indicates that there is no real benefit in making deta iled creep-strain measurements on stub angles. The creepocity (ratio o f creep strain to initial strain) measured on angle stubs is relativel y small (14.4% after 2,500 h at a stress level averaging 45% of the pr oportionality limit) and should not cause geometrical integrity proble ms at the stress level considered. Finally, Boltzman's superposition p rinciple was used to compare the experimental creep-recovery results w ith predictions from Findley's model, and agreement was also observed.