How it works

A CLT wall is stiff and strong as a panel. Under lateral load it moves mainly because its connections deform: hold-downs stretch, screws between panels slip, and angle brackets let it slide. The tool follows one published analytical model of that behaviour and shows the result.

1 · Three ways a multi-panel wall rocks

Coupled-panel (CP) · Intermediate (IN) · Single-wall (SW). Dots mark the corners the panels pivot about.

Coupled-panel: every panel tips about its own corner and the screws between panels slip. This happens with a stiff hold-down, soft joints or heavy vertical load. Single-wall: the joints are stiff enough that the whole wall tips as one piece about its far corner. Intermediate: a mix of the two. As the push grows, a wall can move from CP through IN to SW. The stiffness ratio k̃ = k_h/(n·k_c) and the vertical load decide when (Casagrande et al. 2018).

2 · The predicted load–displacement curve

Activation force F_q: the vertical load holds the wall down until the overturning moment exceeds it.
Elastic rocking, one straight segment per kinematic mode, with a change of slope each time the mode changes.
First yield: the hold-down or the joint screws reach their strength. Whichever yields first decides the final behaviour (hold-down first → single-wall, screws first → coupled-panel).
Plastic branch to ultimate for the two cases with closed-form equations (Nolet 2017). For other cases the curve stops at first yield, and the results say so.

Sliding on the angle brackets and in-plane shear and bending of the CLT panels are added on top as elastic springs (Casagrande et al. 2024). If the brackets would fail before the wall reaches its rocking capacity, the curve is cut there and "sliding governs" is reported.

3 · Reading the screen

Move the load slider to step along the predicted curve. The elevation redraws the deformed shape, with the original position dashed. Deformation is exaggerated by the factor shown.
Connector arrows: T is the hold-down tension, V the shear in each vertical joint, A the force per angle bracket (all in kN).
Deflection bars split the top displacement into rocking, sliding, panel shear and panel bending.
Parameter sweep re-runs the model over a range of one input and plots capacity and secant stiffness K_0.4. Both the curve and the sweep export as CSV.

4 · What it does not do

Single storey, monotonic load, identical panels, hold-downs at the wall ends only, no openings. Connector properties are your inputs; the tool does not derive them from fastener design rules. The defaults are illustrative values from the source examples, not product data. Every equation, assumption and default is listed in METHODS.md.

Sources

Casagrande, Doudak, Mauro & Polastri (2018). Analytical approach to establishing the elastic behavior of multipanel CLT shear walls subjected to lateral loads. J. Struct. Eng. 144(2). doi
Nolet (2017). Analytical methodology to predict the behaviour of multi-panel CLT shearwalls subjected to lateral loads. MASc thesis, University of Ottawa. open access
Nolet, Casagrande & Doudak (2019). Multipanel CLT shearwalls: an analytical methodology to predict the elastic-plastic behaviour. Eng. Struct. 179. doi
Casagrande, D'Arenzo, Masroor, Gavrić & Doudak (2024). An analytical matrix approach for the prediction of the elastic lateral displacements of CLT platform-type lateral load resisting systems. Structures 64, 106490. open access