The first viaducts to be built using “absolutely” earthquake-proof expansion joints which will give “complete” seismic protection are to be installed in Mexico.
The two largest viaducts, which will be 3.9km and 1.4km long, are part of the new 57.7km long Toluca–Mexico City railway which is due to become operational in early 2021.
The railway is the first to cross the region which can experience “extremely high” seismic accelerations of up to 0.77g.
The new guided cross-ties joints will be situated at the ends of the individual bridge sections. A complex system of bearings, dampers and elastomeric spring isolators then ensure structural stability, function and safety for load cases ranging from the normal braking and acceleration forces of passing trains to the maximum considered earthquake (MCE).
The new joints for the structures have been designed by German joint specialist Maurer.
Piers for the viaducts are up to 65m high with spans of ranging from 55m to 64m and are situated in the highly seismic zone in the mountains.
Maurer said the new joint was based on the principle of the swivel joist expansion joint used in road construction, although it said it is “much more stable” to withstand the high axle loads of crossing trains travelling at up to 350km/h, fatigue-free.
Due to the high requirements placed on the dampers and isolators, they have been tested on both the “shake table” of the University of California in San Diego and on the earthquake simulator of the University of Messina.
Production of the bearings started in September 2016 and will be delivered and installed gradually. Installation of the last joints is scheduled for the autumn of 2020.
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