Abstract
This paper presents a nonlinear dynamic analysis procedure used for the investigation of the response of a tensegrity bridge to a selected sudden cable rupture. In order to simulate a cable rupture, for the loaded or unloaded geometry of the tensegrity structure, a geometrical nonlinear analysis is performed, and the cable end tensions projected in the global coordinate system are determined. Next, these forces are applied as external nodal forces to the tensegrity structure, from which the selected cable has been omitted (damaged structure). Next, the nonlinear equation of motion of the tensegrity bridge subjected to dynamic loads is discretized and integrated in time using the unconditionally stable Newmark constant-average acceleration method combined with a Newton-Raphson iterative scheme. The dynamic simulation is initiated by cancelling the vector of external forces representing the damaged cable. For each case, the largest tension force in the cables, the largest compression force in the struts as well as the largest average midspan displacement are determined. The maximum tension obtained in all the bridge cables was way below their tension capacities for the unloaded bridge and exceeded them for only one case of the loaded one. However, the maximum compression forces obtained in the struts of the bridge were below their compression capacities. The limit deflection has been exceeded only for of the loaded bridge and for several cases of cable rupture. Nonlinear dynamic instabilities caused by cable slackening were observed in all simulations.
Highlights
“Tensegrity” systems are lightweight spatial reticulated structures combining cables in tension and bars in compression in a self-equilibrated state providing stiffness and stability to the system
Nonlinear dynamic analysis is intensively investigated by researchers, most of existing studies were conducted on simple tensegrity systems
The nonlinear dynamic response of a tensegrity bridge subjected to selected broken cables is investigated for two loading cases
Summary
“Tensegrity” systems are lightweight spatial reticulated structures combining cables in tension and bars in compression in a self-equilibrated state providing stiffness and stability to the system. Bel Hadj Ali et al (2010) studied the static and dynamic behavior of a tensegrity-based pedestrian bridge and showed that such type of structure could be a viable solution for small span footbridges. Based on both total and updated Lagrangian formulations, Tran and Lee (2011) developed a model for tensegrity systems accounting for both geometric and material nonlinearities. The tensegrity concept is increasingly adopted in built structural systems, many engineers still have queries about this type of structures especially in relation with their nonlinear behavior and stability under cable rupture. The effect of the cable rupture on the displacements of critical points and member internal forces as well as on the stability criterion are discussed
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