Enhancement of seismic performance of beam-column joint connections using high performance fiber reinforced cementitious composites

In this paper, six half-scale exterior beam-column joint connections are casted and tested under cyclic loads to investigate and evaluate the possibility of using high performance fiber reinforced cementitious composites (HPFRCC) to remove the necessity of confining (transverse) reinforcements and solve the construction problems in beam-column joints under seismic loads. Fiber reinforced cementitious materials used in this study comprises 2% volume fraction of hybrid fiber, hooked end steel fiber and hybrid macro synthetic fibers. The basic mechanical properties of HPFRCC are determined by uniaxial tension and compression tests. The hysteretic behavior, ductility, stiffness, energy dissipation, damping characteristics and cracking patterns of HPFRCC beam-column joint connections are evaluated and compared with those of normal concrete with and without special seismic requirements in joints. The test results revealed that HPFRCC connections considerably enhanced shear and flexural capacity as well as deformation and damage tolerance behavior at post-cracking stage compared to those of normal concrete at ultimate stages. Moreover, the failure mode of HPFRCC specimens changed from shear mode to flexural mode compared to the failure mode of concretes without required seismic details.