The effect of CFRP strip stirrups on the shear strength of SCC high strength lightweight concrete beams

The development and applications of structural high-strength lightweight self-consolidating concrete (HLWSCC) have increased significantly in recent years owing to its better mechanical properties and economic benefits over conventional normal weight concrete (NWC). This paper presents the results of an experimental and analytical study to evaluate the shear performance of HLWSCC beams internally reinforced with CFRP sheet stirrups. In addition to one control specimen, seven beams were cast and reinforced with CFRP sheet stirrups. The variables studied in the experimental program were the number of layers, strip spacing, strip (sheet) width, and strip configuration of CFRP stirrups. All the beams were subjected to four-point bending, and the experimental results include load–deflection response curves and strain values along with the failure modes. Experimental results showed that all the tested beams failed due to shear tension failure. However, some of the specimens also failed due to the rupture of CFRP sheet stirrups. The addition of CFRP sheet stirrups has substantially increased the shear capacity of HLWSCC beams and the increase in shear strength ranged from 64% to 140% over the control specimens. Additionally, the nominal shear strength was predicted using various Fiber Reinforced Polymer (FRP) design standards, including ACI 440.1R-15, CSA S806-12, CSA S6-14, CNR-DT (2013), JSCE, and Fib Bulletin 40. Comparing the predicted and experimental shear strength has shown that current design standards can be used safely to predict the ultimate shear strength of HLWSCC beams reinforced with newly innovative CFRP sheet stirrups.