Axial Behavior of Columns with Glass Fiber-Reinforced Polymer Composite Shells and Syntactic Foam Core

Abstract

Syntactic foams (hollow glass macrospheres bonded with a polymer matrix) encased in glass fiber-reinforced polymer (GFRP) composite shells have the potential to enhance structural performance and energy absorption. To investigate this hypothesis, several load carrying structural columns with a GFRP composite shell encasing a syntactic foam core were designed, manufactured, and tested under axial compression, with a focus on optimal energy absorption and compressive force resistance. The structural responses of column specimens and the foam core alone were assessed via load, strain, and deflection responses. The following parameters were varied to induce different failure modes: (1) shell thickness; (2) fiber volume percent in both the longitudinal and circumferential directions; (3) syntactic foam density; and (4) cross-shaped fiber orientation of GFRP web. Based on the experimental data, a strength prediction model was developed to predict the axial load capacity, including the buckling limits of the hollow GFRP tubes and syntactic foam columns with GFRP shells. The predictions are relatively simple and provided good accuracy when compared with the experimental data.