David Yeomans

Stresses get the lower case f and deflections the Greek ∂ (delta)

The simplest iron or steel bridge structure is just a series of girders resting on piers. The ill‐fated Tay Bridge had been just that, and so is its replacement that is still in service today, but these designs required a great many piers and so a great many underwater foundations. When Baker came to bridge the Firth of Forth, he chose to limit his foundations to shallow water and an island and build gigantic cantilever structures to span across the gaps between them (Figure 1.3). A cantilever is a structure that is supported at one end only, unlike a beam, which is supported at both ends

arms are in tension as they pull inwards. The timber struts have pairs of arrows pointing outwards, and we know that these are in compression as they push outwards and upwards