Capacity Design–Based Seismic Forces in Floor-to-Beam Connections of Precast Concrete Frames

The stiffness and strength of roof units and their connections to supporting beams are fundamental parameters to define the diaphragm behavior of precast structures. In this paper, an analytical method for the calculation of actions in floor-to-beam connections of roof systems without topping slab and without floor-to-floor connections is presented. The proposed procedure can be applied to rectangular single-story precast concrete frames of industrial buildings. One-span, multi-bays regular frames, characterized by symmetry of stiffness and mass distributions are analyzed by assuming floor-to-beam connections with infinite stiffness and strength. The procedure is applied in the perspective of capacity design approach by providing practical formulations for the design and retrofitting of floor-to-beam connections. This approach aims at concentrating the critical regions, where energy dissipation of the structure occurs, at the base of columns designed to fail in bending. An over-resisting behavior of the connections is achieved by over-proportioning them with respect to the resistance of the critical regions. To check the effectiveness of the presented approach, the results obtained with the analytical method are compared with the results of finite element analyses.