Seismic Behavior of Slab-Column Connections Using High Performance Fiber Reinforced Concretes

Significant research efforts have been devoted to achieving high performance of slab – column connections subjected to lateral loading. Solutions such as using stirrups and headed studs have been shown to work well. With the development of concrete materials with enhanced properties, new possibilities have arisen to employ solutions that are easy to apply and cause less congestion of reinforcement. A total of nine tests on flat slab specimens subjected to combined gravity and lateral loading are discussed, including two new specimens with High Performance Fiber Reinforced Concrete (HPFRC) over a limited region near the column. The main experimental variables were the flexural reinforcement ratio and the punching shear improvement method: none, headed studs, High Strength Concrete (HSC) or HPFRC. It is shown that excellent behavior is achieved with a relatively small amount of HPFRC, extended up to 1.5 times the effective depth of the slab from the face of the column. Punching was completely avoided until the end of the loading protocol (6% drift) for the specimens with HPFRC, whereas reference specimens without punching shear reinforcement failed at 1% drift and specimens with HSC reached 3% drifts. Additionally, the use of HPFRC led to an increased unbalanced moment transfer capacity and lateral stiffness, though this effect was more pronounced for specimens with lower flexural reinforcement ratio.