Dynamic amplification factors in cable-stayed structures

The aim of this paper is to demonstrate that in cable-stayed structures dynamic amplification factors caused by the sudden breakage of cables can be larger than 2. This fact is extremely important since design guidelines for cable-stayed bridges indicate that the highest value for such factors is 2, whereas under certain circumstances that value could be considered unsafe. We set out the conditions that lead to that value being surpassed. We also show that the dynamic amplification factors related to deflections are lower than those related to bending moments and that the latter are in turn lower than those related to shear forces. Two examples are given: one involving the abrupt application of loads to a simply supported beam and the other the accidental breakage of a stay cable in a bridge with under-deck cable-staying.