Damage due to Vibrations from Automotive Traffic on Slabs of the La Cabrera Viaduct

Daños por Vibraciones del Tráfico Automotor en Losas del Viaducto La Cabrera

Abstract

The vibrations of the slabs due to automotive traffic are responsible for the accumulated damage to the slabs of the La Cabrera viaduct, which was demonstrated through dynamic analyzes of the behavior of said slabs. The concentration patterns of shear stresses and moments coincide with the damage observed in the slabs. The effect is more pronounced for 21 cm thick slabs than for 29 cm thick slabs. None of the studies on the La Cabrera viaduct make any reference to vibrations being the potential cause of said damage. This finding is important and coincides with the literature consulted on damage to bridges due to automobile traffic. It was also analytically demonstrated that the combined effects of the magnitudes of the loads together with the number of axles on the slabs due to the speed of the vehicles and the vibration periods of said vehicles produce superposition of effects in the slabs that exceed the normative values. allowed for all structural control variables. The excess load was measured and was very significant; However, there is no active control mechanism for cargo access to the viaduct. The inertia of the slabs and support beams makes the frequency of their vibrations very similar to those of heavy vehicles that circulate. Additionally, deflections due to moving load and superposition of vibrations generate significant amplification factors for both shear stresses and moments which generate damage patterns. The concrete of the slabs is very damaged as a result of the cumulative fatigue process that is irreversible. Therefore, the slabs must be replaced just like the current maintenance method.