Gusset plate connections under monotonic and cyclic loading

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986 Can. J. Civ. Eng. Vol. 32, 2005 Table 3. Comparison of monotonic analysis with Rabinovitch and Cheng (1993) test results. Tension loading Compression loading Specimen Test capacity (kN) Predicted capacity (kN) Test/predicted Specimen Monotonic compression loading Modelling To analyze the behaviour of gusset plates loaded monotonically in compression, initial imperfections were introduced into the model. Since initial imperfections were not measured for any of the specimens tested by Yam and Cheng (1993) or by Rabinovitch and Cheng (1993), a number of initial imperfection shapes and magnitudes were studied. Three initial imperfection shapes were investigated, namely a full sine wave, a quarter sine wave, and a shape con- Test capacity (kN) Predicted capacity (kN) Test/predicted A1 1794 1923 0.93 GP1 1956 2073 0.94 A2 1340 1245 1.08 GP2 1356 1342 1.01 A3 1884 1928 0.98 GP3 742 711 1.04 A4 1265 1248 1.01 Fig. 6. Initial imperfection shapes: (a) quarter sine wave and (b) buckled configuration. Fig. 7. Effect of initial imperfection magnitude on gusset plate behaviour in compression. Fig. 8. Finite element model of Rabinovitch and Cheng (1993) stiffened gusset plate specimens A3 and A4. structed by scaling the buckled configuration of the gusset plate by an appropriate constant to obtain the desired imperfection magnitude (Fig. 6). The three initial imperfection magnitudes used for this comparison were 0.05, 0.5, and 5 mm. In this study the initial imperfection magnitude was taken as the maximum out-of-plane imperfection assigned to any of the gusset plate nodes. The manner in which the clamping of the gusset plate by the splice members was modelled was found to be important (Walbridge et al. 1998). The best results were achieved with a perfect clamping model, that is, with the out-of-plane degrees of freedom of each splice member node overlapping the gusset plate linked to that of the corresponding node on the gusset plate. © 2005 NRC Canada
Walbridge et al. 987 Fig. 9. Springs used to model bolt slip: (a) spring 1, (b) spring 2, and (c) spring 3.. Fig. 10. Spring activation sequence for bolt slip model: (a) step1,(b) step2,(c) step3,and(d) step 4. Dashed lines represent springs that are “active” and solid lines represent the “effective” spring. Results On one hand, it was found that initial imperfection magnitude has a significant effect on the buckling capacity of the gusset plate; in general, the larger the initial imperfection, the lower the buckling capacity. On the other hand, it was found that the shape of the initial imperfection was much less critical. The quarter sine wave shape was used in subsequent analyses. The effect of initial imperfection magnitude was studied using a model of specimen GP3 from Yam and Cheng (1993). Figure 7 shows axial load versus displacement curves for models of the gusset plate connection with three different initial imperfection magnitudes. The figure indicates that an initial imperfection magnitude of 0.5 mm overestimates the capacity of the assembly, whereas a 5.0 mm imperfection results in an underestimation of the test result. Based on the results of the analysis described above, new models of specimens GP1, GP2, and GP3 from Yam and Cheng (1993) were constructed. A quarter sine wave initial imperfection with a magnitude of 2.0 mm was used, and flexible beam and column members along the gusset plate boundaries were included in the model. Table 3 shows a summary of the predicted and actual capacity in compres- © 2005 NRC Canada
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Gusset plate connections under monotonic and cyclic loading

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