Well-designed and well-constructed timber structures can have an excellent response under earthquake loading due primarily to the high strength to weight ratio of wood. Nevertheless, the seismic performance of timber buildings involves various inter-related factors that need to be properly understood. Many of the aspects related to the resistance of timber buildings spring from the atypical mechanical characteristics of wood as a construction material. In particular, there are significant differences in wood strength and stiffness depending on the orientation of the load with respect to the grain direction as depicted in Figure 8.1. It follows from the schematic strain-stress curves, indicated in Figure 8.1, that tension failures in wood are brittle and should be avoided while compressive behaviour (parallel to the grain) is a preferred mode of failure but should be limited. In fact, it is a typical approach of codes


8.1 Introduction 213 8.2 Modern structural systems 215 8.3 Lateral deformation modes of timber walls 215 8.4 Seismic response of connections 216 8.5 Eurocode 8 definitions, design concepts and material properties 219 8.6 Ductility classes and behaviour factors 221 8.7 Structural analysis 221 8.8 Detailing rules 222 8.9 Safety verifications and capacity design 222 8.10 Design example 223

8.10.1 Introduction 223 8.10.2 Weight and mass calculation 224 Dead load 224 Imposed load 226 Seismic mass 226

8.10.3 Seismic base shear 226 8.10.4 Shear load distribution and total moment calculation 227 8.10.5 CLT shear wall actions 228 8.10.6 Seismic strength design checks 229 8.10.7 Capacity design 229 8.10.8 Damage limitation and final design 231

References 232

of practice to ensure a ductile failure mechanism by inducing yielding in metallic connectors between timber members instead of the wood material itself in order to provide a sustained source of energy dissipation during seismic shaking.