Keywords: timber diaphragm, wood shear wall, sheathing-to-timber joint, finite element model, non-linear analysis, racking capacity, softening behaviour.

Multi-storey wood buildings are frequently built nowadays. For the horizontal stability of such buildings, diaphragm action in the walls is very important. Roof and floor diaphragms distribute lateral loads to the shear walls, which in turn transfer the loads to the foundations. Important factors that have great influence on the load- carrying capacity and the structural performance of a shear wall are:

a)

the fastener characteristics, with respect to different grain and load directions and edge distances;

b)

the boundary conditions, with respect to fully or partially anchored leading stud and bottom rail and with respect to intercomponent connections to transverse walls and flexible floors;

c)

the loading conditions, with respect to gravity loads; and

d)

the sheathing, with respect to fully or partially sheathed segments.

However, these non-linear structural characteristics have not been fully understood yet. This lack of knowledge limits the potential for design optimisation.

A main objective of this study is to establish non-linear finite element models so that properties of various individual components with their different combinations can fully be taken into account and the non-linear behaviour of the sheathed timber diaphragms can be analysed numerically. The finite element models will be used to conduct parametric studies to obtain the different optimum design parameters and to make comparisons with the new plastic design approach for sheathed wood shear walls, see Källsner et al. [1].

This paper presents the results of numerical analysis and simulation of sheathed timber diaphragms using non-linear finite element models. The results show that the failure modes and racking capacity can be predicted numerically and that they are in good agreement with the results observed experimentally. All the analyses are made by the finite element program ABAQUS [2].

The two-dimensional non-linear finite element models are also presented in the paper. Particular consideration of the characteristics of the fasteners and of the framing joints has been made. Besides studying different loading and boundary conditions, the models can be used to analyse diaphragms with different panel configurations, fastener characteristics and fastener spacing.

1

B. Källsner, U. A. Girhammar and L. Wu, "A simplified plastic model for design of partially anchored wood-framed shear walls", CIB/W18 Meeting, Venice, Italy, 22-24 August, 2001.

2

ABAQUS Manual, version 5.8 and version 6.2

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