Cross-lam roof diaphragm for the seismic retrofitting of historical masonry churches

In the seismic restoration of historical masonry churches, a strategy based on the realization of a dissipative roof diaphragm could be useful in order to limit the out-of-plane lateral walls (rocking mechanisms) and specially to reduce the in-plane shear transferred from the roof to the transversally oriented frames (or head walls) of the church. Several structural solutions can be proposed but, in many countries, the ones based on the use of wood are the most accepted by the Cultural Historical Offices according to the conservative restoration criteria. In this paper, the cross-lam panel solution is proposed as a dissipative roof structure able to satisfy the seismic requirements by improving the transversal nave response. In order to optimize the dissipative effects of the cross-lam roof structure, the behavior of the panel-to-panel and wall-to-panel steel connections are investigated by analyzing different configurations. Particularly, different numerical representations of the connections are discussed and applied on a specific case study. Furthermore, regarding the connections implementation, nonlinear analyses are performed to better identify the steel dissipative effects on the crosslam panel, especially in terms of in-plane shear