Strengthening Slender Steel Compression Members Using a Fibre-Reinforced Polymer Shell Buckling Restrained Bracing System

Abstract

In this paper, the structural properties of slender steel members reinforced against buckling by fibre-reinforced polymer (FRP) composite shells filled with self-consolidating grout is investigated. A total of 9 small-scale specimens were prepared and tested under uniaxial compression. The main test parameters were FRP shell diameter (36 mm, 49 mm and 61 mm) having a shell length of 600 mm. Each specimen was fabricated using cold rolled steel bars (25.4 mm by 6.35 mm) with lengths corresponding to 30 mm longer than the FRP shell and a self-consolidating grout with a compressive strength of approximately 20. Two failure modes were observed during testing: system buckling and steel yielding. Overall, provided the FRP-BRB system was sufficiently sized the system was successful in changing the failure mode of the steel core from buckling to yielding. On average, the steel carried 94% of the load with the grout and FRP shell carrying only 6% and 0.3% at the yielding, respectively.