Considerations Regarding the Dynamic Stability in Case of a Damage for Tower Cranes

Stability is an important indicator when sizing cranes. According to the way forces are considered, there is static stability and dynamic stability. Ensuring stability is done by determining the so-called stability coefficient, in two extreme cases of possible departures from stability, respectively with load and without load. Static stability is a necessary condition for the stability of the crane, but not sufficient. Due to the dynamic demands, the dynamic stability must also be taken into consideration. But dynamic solicitations are, unlike static ones, much more difficult to evaluate. In general, the problems raised by dynamic stability are difficult problems, and their treatment is often done under simplifying and covering assumptions. Using modern means of calculation and algorithms developed especially for laborious and in large numbers calculations, the problem of dynamic stability can be approached from positions very close to reality. But, before making this investment of intellectual effort, it must be tested if the problem of dynamic stability is a real, important problem or, being a minor problem, it can be included in the conditions that ensure static stability. The present work presents a study on the dynamic stability in case of a damage for tower cranes. It is analysed in detail the case of dynamic stability when the load suddenly falls into the hook, when the load falls from the hook and, finally, an energetic interpretation of the stability for tower cranes is formulated.