TIMBERTECH BUILDINGS

Modelling Timber Walls | TimberTech Solutions For Timber Engineering

The macro-element developed at the University of Trento

Nowadays the modelling of structures with timber walls with a finite element software could be complicated: in particular the correct evaluation of wall lateral stiffness is difficult to achieve since it depends on different contributions (shear deformations of the walls, deformations of the connections, rigid body rocking due to hold-down deformation…) which are difficult to define in the model.

On the other hand, with the software TimberTech Buildings the definition and the modelling of timber walls (CLT or platform frame walls) results easy because the “assembly” of all the components of the wall is up to the implemented numerical models derived by the research conducted at the University of Trento.

The model implemented in the software is able to consider all the stiffness components in a timber wall and its connections. A description of the model was published in the paper “Daniele Casagrande, Simone Rossi, Tiziano Sartori, Roberto Tomasi, Proposal of an analytical procedure and a simplified numerical model for elastic response of single-storey timber shear-walls, in Constrution and Building Materials (2015)”.

Modelling of a platform frame wall

Case study

INTRODUCTION

This section shows a comparison between a modelling of a light-frame wall with a finite element software and a modelling with the software TimberTech Buildings. The aim of this comparison is to calculate and compare the several stiffness contributions given by the elements forming the wall.

A platform-frame wall is made of timber studs and beams braced with sheating panels used to transfer the horizontal loads to the foundations.
The elastic horizontal displacement of a light timber frame wall subjected to an horizontal force can be obtained by adding the following contributions of deformation.
Displacement due to the connections between the sheathing and the frame
Displacement due to the sheathing panels
Displacement due to the rigid body translation
Displacement due to the rigid body translation

MODELLING WITH A FINITE ELEMENT SOFTWARE

Modelling timber light-frame walls through finite element software is very onerous and complicated. As shown in the following figure, to evaluate correctly the horizontal stiffness of the wall, you need to use:

MODELLING WITH TIMBERTECH BUILDINGS

Modelling with TimberTech Building is very simple and fast. The user has to define the geometrical and mechanical properties for each wall tipology.

Frame Properties
Frame properties
Sheating board properties

CASE STUDY

In this case study there is a comparison between the software TimberTech Buildings and a finite element software for a wall with a length of 2 m and an height of 3 m. The wall presents the following characteristics:

Results

Comparison between the results obtained with Timbertech Buildings and the results obtained with a finite element software

Deformation contributions

Deformation contributions obtained with TimberTech Buildings

From the table above, we can see how the results of the analytical model implemented in TimbertechBuildings are very similar to the results obtained with a finite element software.

We achieved a wall stiffness that is very close to those obtained with a finite element software in spite of a more simple modelling of the wall.

In the table above, it is shown that the contribution of deformation given by the rigid body translation is negligible. On the other hand, the fasteners deformations and the rigid body rocking (hold-down connection) are very important.

Sheathing to framing connection deformation
Sheathing panel shear deformation
Rigid body translation
Rigid body rotation

Modelling of a CLT Wall

CASE STUDY

This section shows a comparison between a modelling of a CLT wall with a finite element software and a modelling with the software TimberTech Buildings. The aim of this comparison is to calculate and compare the several stiffness contributions given by the elements forming the wall.

The elastic horizontal displacement of a jointed CLT wall subjected to a horizontal force can be obtained by adding the following contributions of deformation:

MODELLING WITH A FINITE ELEMENT SOFTWARE

As shown in the following figure, to evaluate correctly the horizontal stiffness of the wall, you need to use:

MODELLING WITH TIMBERTECH BUILDINGS

Modelling a jointed CLT wall with TimberTech Building is very simple and fast. The user has to define the geometrical and mechanical properties for each wall tipology.

CLT wall properties in Timbertech Buildings

Joint tipology

CLT wall properties in Timbertech Buildings

Joint properties

From the table above, we can see how the results of the analytical model implemented in TimbertechBuildings are very similar to the results obtained with a finite element software.

We achieved a wall stiffness that is very close to those obtained with a finite element software in spite of a more simple modelling of the wall.

In the table above, it is shown that the contribution of deformation given by the rigid body translation is negligible. On the other hand, the fasteners deformations and the rigid body rocking (hold-down connection) are very important.

Table of Results
Contributions of deformation in Timbertech Buildings
From the table above, we can see how the results of the analytical model implemented in TimbertechBuildings are very similar to the results obtained with a finite element software. We achieved a wall stiffness that is very nearly to the each one obtained with a finite element software in spite of a more simple modelling of the wall.

Joint's fasteners deformation

Rigid body translation

Panel shear deformation

Rigid body rotation

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