Analysis of experimental research data of precast slabs operation with a new variant of splined joint

The authors have conducted field tests of precast slab models with a new variant of splined joint, characterized by the presence of frames in the core zone of hollow-core slabs with free length of longitudinal reinforcement. The comparative analysis on operation of slab samples with splined joints, from slabs with frames in the core zone and without it is conducted. The analysis results show that the presence of free length of longitudinal reinforcement of hollow-core slab frames can improve the strength and stiffness of precast slabs. It’s concluded that stiffness of a new variant of the splined joint is higher than that of analogues and decreases with increasing load, at small loads it’s close to the anchorage. Based on experimental data three stages of slab operation are identified. At the first stage the slab works as an elastic system. At the second stage it works as a statically indeterminate system with constrained deformations. The crossbars run on bending with torsion that leads to the increase of stiffness of precast slabs for bending in filled-in panels of hollow-core slabs. At the third stage the growth of plastic deformation is observed. The authors have drawn a conclusion that anchoring to crossbars of free length of longitudinal reinforcement of hollow-core panel frames enables collaboration of precast slab elements.