Seismic performances and behavior factor of post-and-beam timber buildings braced with nailed shear walls

• Procedure to evaluate the seismic performances of a post-and beam timber buildings.
• Application of the method on different building configurations.
• Validation of the model by comparison with experimental tests on timber shear walls.
• Considerations about the factors which affect the behavior factor q.
• The maximum behavior factor allowed in Eurocode 8 may be unsafe.

A procedure to assess the behavior factor of post-and-beam timber structures based on the Capacity Spectrum Method is herein presented and the results of numerical simulations performed on three different building configurations, two and three storey buildings regular in plan and a two storey building non-regular in plan, are shown. The procedure assumes that the dissipative capacity of the structure is concentrated in the nailed connections of the components, whose non-linear behavior is derived by means of experimental tests. The results obtained, concerning the three types of buildings with three different proportioning criteria for the connections, are compared in terms of force–displacement capacity curves, global ductility, maximum resistant ground acceleration and behavior factor q. The global ductility ranges from 1.8 to 2.4. The values of the behavior factor q of the two storey buildings ranges from 2.4 to 3.8, depending on the shear redistribution amount among the shear walls; higher values (3.0–4.4) were obtained for the three storey buildings. Moreover, a nail distribution at each level according to the storey demand increases the dissipative capacity of the structure. The results of the study evidence that the maximum value of the behavior factor allowed in Eurocode 8 for timber structures with nailed shear walls and nailed diaphragms, connected with nails and bolts (q = 5) is in general not possible for post-and-beam timber buildings braced with nailed shear walls.