Question

Briefly describe how the following is handled in wind load analysis:
i) Loading and cladding
ii) Fixity of cladding to a structural member
iii) Design of a structural member carrying cladding.

Answer 1

i) Cladding

Whilst cladding is generally attached to the structure of the building, it typically does not contribute to its stability. However, cladding does play a structural role, transferring wind loads, impact loads, snow loads and its own self-weight back to the structural framework.

In particular, wind causes positive and negative pressure on the surface of buildings and cladding must have sufficient strength and stiffness to resist this load, both in terms of the type of cladding selected and its connections back to the structure.

Loading

Wind loading is the critical loading on tall buildings, and indeed it was to withstand wind loads more efficiently and economically as buildings get higher and higher that shear wall systems were developed. Yet the wind loads used in design remain, as we know, largely empirical and unrelated to reality. The actual effect of wind on buildings is at last, however, being studied on a really fundamental basis, It is evident that we need much more wind tunnel testing under the right conditions of turbulent air flow, especially on unusual shapes, and that much more information is required on the degree of mechanical andaerodynamic damping in tall structures, and on their natural modes of vibration. It is a pity there are so few workers in this most important field.

ii) Fixity of cladding : Cladding in construction is material applied over another to provide a skin or layer and used to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings. Between the cladding and the wall there is a cavity where rain can run down.

iii) Design of a structural member carrying cladding :

Engineering principles mainly used in this analysis
-Statics

-Stregnth of materials

- Material selection

- Machine elements

- Finite element method

And for the cladding mainly design element is the material :

Cladding can be made of any of a wide range of materials including wood, metal, brick, vinyl, and composite materials that can include aluminium, wood, blends of cement and recycled polystyrene, wheat/rice straw fibres.

Materials used for cladding affect vulnerability to fire.