Effects of temperature changes on the behaviour of a cable truss system

A previously published analytical solution for the analysis of a bi-concave cable truss structures under arbitrary vertical loads consisting of uniformly distributed and/or concentrated loads [A. Sadaoui, K. Lattari and A. Khennane, “A novel analytical method for the analysis of a bi-concave cable-truss footbridge”, Engineering Structures 123 (2016) 97-107] is extended in the present to include the effects of temperature changes. A reference base temperature of 20 °C was considered as ambient. The material properties were assumed to be independent of temperature change, which is justified for small changes in temperature in the order of 50 °C. Positive and negative temperature increments were applied and their effects on the displacements and the forces developed in the elements were assessed. The obtained results were validated using finite element analysis. It was found that a temperature decrease intensifies the stresses, and susceptible of catastrophic failure because of certain structural steels exhibiting a shift from ductile to brittle behaviour if the temperature is lowered below a certain threshold. It was also found that a positive temperature change of 50 °C, which is not unusual in many parts of the world, results not only in increased deflections but also in increased relaxation of the tensile forces in the cables, which could affect serviceability. Most importantly, it was found that the loss of prestress is more severe (up to 58%) in the deck cable, which provides the stabilizing effect for the whole cable truss system.