Seismic strengthening and seismic improvement of timber structures

• Seismic strengthening plans should consider the levels of structure, element, joint.
• The structural scheme must be verified to balance horizontal forces.
• Slab reinforcing options yield various stiffness levels apt to fit different needs.
• In earthquake conditions, joints disassembly and brittle failure must be prevented.
• Inappropriate positioning of reinforcement even in small amount may cause brittleness.

In European seismic areas timber structures are found as building frames, in combination with masonry infills, in bridges, but most frequently in roof structures and floor slabs of traditional buildings. Seismic strengthening of existing structures should provide a well-defined and simple path to seismic forces, maintain timber members elastic, and develop as much as possible the post-elastic behaviour of joints. Provisions must be adopted to avoid sudden loss of capacity and brittle failure, and to foster ductility. Different criteria for seismic strengthening of floor slabs and of carpentry joints are presented.