Difference between revisions of "Chirajara Bridge"
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Normally the cross tie beams in a concrete cable stayed bridge tower are at least 2 meters thick with several rows of prestressing cables. For the Chirajara Bridge the cross tie was just .6 meters thick with only one row of 12 prestressing cables holding the two sides of the tower together. | Normally the cross tie beams in a concrete cable stayed bridge tower are at least 2 meters thick with several rows of prestressing cables. For the Chirajara Bridge the cross tie was just .6 meters thick with only one row of 12 prestressing cables holding the two sides of the tower together. | ||
| − | Although many of the world's cable stayed bridges have giant concrete wall "diaphragms" below the cross tie, rarely are they used to restrain the lateral tension of the tower legs. The Chirajara Bridge engineer assigned #4 stirrups vertically every 20 cm within the diaphragm which was not nearly strong enough to counter the load path change between the upper A-shape columns of the tower and the lower V-shape columns that focus the weight of the bridge down into the narrow foundation pad. | + | Although many of the world's cable stayed bridges have giant concrete wall "diaphragms" below the cross tie, rarely are they used to restrain the lateral tension of the tower legs. The Chirajara Bridge engineer assigned #4 rebar stirrups vertically every 20 cm within the diaphragm which was not nearly strong enough to counter the load path change between the upper A-shape columns of the tower and the lower V-shape columns that focus the weight of the bridge down into the narrow foundation pad. |
After imploding the remaining east tower and deck, a new Chirajara Bridge rose above the original foundations but with new, V-shaped towers that are not as reliant on cross tie beams to transfer the loads down from the upper tower stays to the foundation. | After imploding the remaining east tower and deck, a new Chirajara Bridge rose above the original foundations but with new, V-shaped towers that are not as reliant on cross tie beams to transfer the loads down from the upper tower stays to the foundation. | ||
Revision as of 21:21, 19 June 2020
Chirajara Bridge
Viaducto Chirajara
Guayabetal, Cundinamarca, Colombia
492 feet high / 150 meters high
938 foot span / 286 meter span
2021
Chirajara Bridge is the highest bridge in Colombia with a deck 150 meters above a forested creek that flows into the great Rio Negro River gorge along the Bogota-Villavicencio highway. The strength and elegance put forth by the triangular geometries of the current V-shaped towers hides a sad construction accident that forever tarnished the once perfect track record of zero cable stayed bridge collapses stretching back more then 60 years to the first modern cable stayed span from 1957.
On January 15, 2018, the entire west side of the nearly finished Chirajara Bridge collapsed into the gorge killing 10 construction workers. After an investigation, engineers discovered that the horizontal connection within the diamond-shaped towers was insufficiently designed with a minimal number of prestressing cables. Incorrect calculations were also made about the lateral strength of the concrete diaphragm wall that connected the lower V-shaped legs of the towers.
Normally the cross tie beams in a concrete cable stayed bridge tower are at least 2 meters thick with several rows of prestressing cables. For the Chirajara Bridge the cross tie was just .6 meters thick with only one row of 12 prestressing cables holding the two sides of the tower together.
Although many of the world's cable stayed bridges have giant concrete wall "diaphragms" below the cross tie, rarely are they used to restrain the lateral tension of the tower legs. The Chirajara Bridge engineer assigned #4 rebar stirrups vertically every 20 cm within the diaphragm which was not nearly strong enough to counter the load path change between the upper A-shape columns of the tower and the lower V-shape columns that focus the weight of the bridge down into the narrow foundation pad.
After imploding the remaining east tower and deck, a new Chirajara Bridge rose above the original foundations but with new, V-shaped towers that are not as reliant on cross tie beams to transfer the loads down from the upper tower stays to the foundation.
The older Chirajara Beam Bridge from 1995 still carries eastbound traffic and crosses 90 meters over Chirajara creek.
Completed in 2002, the 122 meter high Pipiral Bridge is the second highest span along the Bogota-Villavicencio route and is located about 10 kilometers to the east of Chirajara.
Sadly the Chirajara Bridge disaster would not be the last cable stayed accident in 2018 as on August 14 a tower and span of the Morandi cable stayed bridge in Genoa, Italy collapsed from excessive corrosion of the wire stays.
Chirajara Bridge satellite image.
Chirajara Bridge location map.
