Modelling of seismic behaviour of light-frame timber structures

This paper investigates the numerical modelling of the cyclic behaviour of light-frame timber structures for non-linear seismic analyses. Two models with different detail levels are used: in the first approach, called M1, every nail connecting the frame to the sheathing is schematized through two non-linear springs, acting on two perpendicular translational degrees of freedom in the plane of the wall, to represent the slip between the two timber parts; in the second approach, called M2, the entire wall is modelled using two equivalent diagonal springs, with mechanical properties derived either from experimental testing on the wall, or from detailed analysis conducted with the M1 approach. Due to its simplicity and limited computational burden, the M2 model is particularly convenient for analyses of entire buildings. The proposed models have been implemented in Abaqus via a purposely developed external user subroutine, and in SAP2000 using the multi-linear pivot hysteretic cycle available in the software library. The models are first validated on experimental tests carried out on screws and individual walls, and subsequently used for modelling an entire light-frame building for which the results of several shaking table tests are available in literature. The experimental-numerical comparison confirms the effectiveness of the models for light frame building and the possibility of use from practicing engineers via the SAP2000 or equivalent software package.