High-strength steel plates in hybrid fiber-reinforced polymer–concrete–steel columns: Concept and behavior

Abstract

Applications of high-strength steel products in civil engineering have been limited by elastic local buckling, by the perceived lack of ductility, and by the perceived difficulties of welding such steels. This article proposes a new column (i.e. high-strength steel plate–concrete-filled fiber-reinforced polymer tube) consisting of an outer fiber-reinforced polymer tube, concrete infill, and encased high-strength steel plates that are connected to each other by bolted angle brackets at discrete elevations. The column offers an ideal opportunity for the use of high-strength steel plates in construction, with their high yield stresses being fully utilized and without welding (and without welding residual stresses). The rationale for the column form and its expected advantages are explained and demonstrated through laboratory tests. Prefabricated glass fiber-reinforced polymer tubes of 1.5 and 3.0 mm thick and 203 mm diameter were infilled with concrete having a nominal strength of 32 MPa, with most specimens encasing steel plates of various configurations and yield stresses ranging from 290 to 455 MPa. Results from concentric and eccentric compression tests involving 13 specimens are presented to confirm the expected structural advantages. The results demonstrated that the concrete in the tested specimens was very effectively confined, and that buckling of all the steel plates was prevented by the encasing concrete up to and beyond the rupture of the fiber-reinforced polymer tubes, leading to full structural utilization of the construction materials and very ductile column responses under concentric and eccentric loadings. The needs for future research on high-strength steel plate–concrete-filled fiber-reinforced polymer tube columns are also discussed.