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Structural principles - Forces

In any building design, the strength and stability of an overall building and its individual components must be considered. This involves structural calculations to work out the effects of all the forces acting on any component in the building and on the building overall. To do this we need to resolve the forces in the system to see what the overall effects are likely to be.

A diagram of a two-storey building is shown. There is snow on the roof of the building contributing to the dead load and this force travels down the structure of the building to the foundation. The live loads inside the building also travel down the structure to the foundation. On the outside of the building the wall has positive wind loads and hydrostatic pressure from water pressure in the ground applied to one side. The wind travels over the building which creates negative wind loads on the other side of the building.
An overview of the many different forces acting on a building.


A flow chart of the forces acting on the building is shown with arrows. Dead loads leads to live loads which flows to hydrostatic pressure, then lateral wind loads which results in a wind uplift. The difference between the start of the pressure at dead loads and the end in an upward wind lift, is the overall effect of the loads or the resultant force.
A summary of all the forces acting on the building.
The dotted arrow is the resultant force,
a force representing the overall effect of the loads.

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