New moment-resisting beam-column joints to increase progressive collapse resistance of precast concrete buildings

Since existing precast RC (reinforced concrete) structures are lacking structural continuity at regions of beam-column connections, they are less resistant to progressive collapse in the event of column removal than CIS (cast-in-situ) RC structures. The prime objectives of current research are to revise the existing precast simple shear beam-column connections and to develop new precast moment connections for increasing the progressive collapse robustness of precast buildings. To achieve these goals, 11 half-scale beam-column assemblies - comprising two beams and three columns - were numerically investigated under the middle column removal scenario using nonlinear 3D FE (finite element) modeling. Two specimens represented typical existing precast simple beam-column connections, and three specimens had revised precast simple connections. Four assemblies were designed with new precast moment connections. The last two specimens represented CIS concrete beam-column connections with continuous and discontinuous longitudinal beam bars to be compared with the precast assemblies. The FE modeling incorporated strain rate-dependent nonlinear constitutive models, contact between different parts in the connection region, and bond-slip at steel bars-to-concrete interface. As a key outcome of this research, the newly developed precast moment connection with the highest rotational ductility was recommended for diminishing the potential of progressive collapse in precast concrete buildings.

Automated summary

The research aims to increase the progressive collapse robustness of precast buildings by revising existing precast simple shear beam-column connections and developing new precast moment connections. The study recommends the newly developed precast moment connection with the highest rotational ductility to diminish the potential of progressive collapse in precast concrete buildings.