Combined Loading Behavior of Basalt FRP–Reinforced Precast Concrete Insulated Partially-Composite Walls

Abstract

The axial and flexure combined loading performance of a slender partially-composite concrete insulated wall design constructed using basalt fiber-reinforced polymer (BFRP) shear connectors and longitudinal BFRP reinforcement is investigated. The load-bearing wall panel sections, 600 mm wide and 2,700 mm long, were first subjected to axial loads ranging from 0 to 900 kN applied to the structural wythe only. The panels were then loaded to failure in four-point bending to develop the axial load-bending moment interaction diagram of the partially-composite system, which was compared to theoretical fully-composite and noncomposite curves. As axial load increased, failure under transverse loading changed from shear-compression of the structural wythe to diagonal splitting of insulation foam and rupture of BFRP connectors, then to crushing of the structural wythe. Composite action by the strength criterion reduced from 47 to 3% as axial load increased from 150 to 900 kN; while that by the stiffness criterion was much lower, 8–2.5%. Relative to a similar steel-reinforced wall panel with the same reinforcement ratio, the tested walls were 60–89% the strength; and the percentage increased with axial load. A method is introduced to estimate the effective centroid of the partially-composite wall in order to calculate the moment from the eccentric axial load applied to this load-bearing system.