How to Model Multi-Storey Masonry Walls?

Masonry is the most common construction type for low-rise residential buildings. At first, the modelling of a simple masonry wall looks very simple. But what is the situation in the case of a multi-storey masonry wall?

In this blog post, we will show you how to divide a masonry wall into wall panels and model them for standard design.

In our following example, we have a two-storey cavity wall masonry building. The outer-leaf is?102.5 mm?wide clay brick and the inner-leaf is?100 mm?concrete blocks.

The DPC at the bottom can be assumed as a pinned support. The inner-leaf is horizontally restrained by the slab in the middle and the roof at the top.

The outer-leaf is pinned top & bottom, and effectively tied to the inner-leaf with wall ties. The sides will be assumed to be continuous or have significant returns.

The loading on the wall is the following from the levels:

To design the wall, at first we have to divide the wall into two separated wall panels:

Wall panel 1 (upper part)

As the wall is a continuous construction, we can assume that the wall panel is fixed on the sides and bottom, while the top edge is pinned to the trusses.

Wall panel G (lower part)

The lower panel is fixed on the sides and the top and pinned on the bottom.

To define the loading on the wall panels, we have to consider the vertical level load eccentricity, as in most cases the slabs are not centrally connected to the walls. The value of the eccentricity is dependent on the construction type. For example:

In?case (a), which occurs if the slab is rigid and the span is short, the eccentricity is:

In?case (b), the eccentricity is:

In our example, the?case (a)?is the relevant and the value of the eccentricity is?20 mm.

Loading on the Wall panel 1 (upper part)

The loading from the roof is only carried by the inner-leaf, as the roof bears onto it.

Loading on the Wall panel G (lower part)

Inner-leaf carries the loading from the current level with eccentricity, plus the self-weight of the wall panel 1’s inner-leaf and the dead?(4.2 kN/m + 5.0 kN/m)?and live load from the roof?(3 kN/m).

The outer leaf carries the self-weight of the wall panel 1’s outer-leaf only. The loading from the above level is taken into account as a concentric loading.

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