EFFECTIVENESS OF STEEL FIBERS VERSUS SHEAR STUD REINFORCEMENT FOR PUNCHING SHEAR RESISTANCE IN SLAB-COLUMN CONNECTIONS SUBJECTED TO BI-AXIAL LATERAL DISPLACEMENTS

摘要

A study of the effectiveness of steel fiber reinforcement and headed shear studs for increasing punching shear resistance and deformation capacity of slab-column connections subjected to earthquake-induced deformations was conducted. Three large-scale slab-column subassemblies were tested under combined gravity load and bi-axial lateral displacements. The slab-column connection in the first two specimens was reinforced with hooked steel fibers in a 1.5% volume fraction, while the connection in the third specimen was reinforced with headed shear studs. All three connections were subjected to a gravity shear ratio of approximately 1/2 during application of lateral displacements. Test results indicate that the use of fiber reinforced concrete in the connection region is an effective design alternative to increase punching shear resistance and deformation capacity of slab-column connections. Maximum connection rotation, just before punching, was approximately 0.04 rad in the two fiber reinforced concrete connections. On the other hand, a peak rotation of 0.027 rad was measured in the specimen with shear stud reinforcement. Inspection of the connection after the test indicated a breakout failure of the concrete engaged by the second line of studs accompanied by severe bending of the bottom steel rail.