Effect of geometric discontinuities on failure of pultruded GFRP columns in axial compression

This paper presents the failure characteristics of pultruded glass fiber reinforced polymer (GFRP) columns loaded in concentric compression. Of interest is the effect of geometric discontinuities on the behavior of the columns, including a bolted splice or utility holes. The local- and global-responses of the columns are examined through a hybrid approach consisting of laboratory experiment and finite element modeling: the test encompasses a total of 50 columns and the model has varying slenderness ratios up to 150. Bolted connections at column supports result in stress concentrations accompanied by crack initiation and propagation, thereby reducing the load-bearing capacity. Tear-up or edge-splitting dominates failure modes at the bolted connections. Spliced members experience fiber misalignment and out-of-plane behavior because of displacement incompatibility between the inner and outer GFRP members bolted together. A weak link provided by side holes, whether symmetric or asymmetric configurations, causes a reduction in axial stiffness and diagonal shearing. The results of modeling indicate that buckling capacity of the column significantly decreases beyond a slenderness ratio of 75 and the presence of side holes is not a contributing factor to the stability of the columns. The design expressions proposed are simpler than existing ones, while provide sufficiently accurate capacity prediction for practice.