Researchers from the engineering faculty of the Universidad del Valle (Univalle) are building on nearly 20 years of work with patents, projects and new research infrastructure for seismic isolators.
Univalle is located in the city of Cali, Colombia, and is in an area of high seismic risk. The university is an epicenter of research on seismic isolators, which are energy dissipation systems that reduce the efforts to which a structure is subjected to increase its safety.
They are usually installed in the basement of a building (or other structures such as bridges) during the construction process and the idea is that when there is lateral displacement, such as during an earthquake, the isolators absorb these displacements, greatly reducing the damage to the structure.
"Currently, beyond hospitals and some other critical infrastructure, there are almost no seismic isolators in buildings in Colombia," said Professor Ortiz.
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| Photo: A virtual model of a building with insulators and one without. Credit: G7 Group/Univalle |
Seismic Isolators from Recycled Rubber
One way to encourage local development is to reduce production costs of insulators.
An example of this is a project led by Professor Ortiz that is developing isolators made from recycled rubber from car tires.
“Internationally, the standard is an isolators made from vulcanized natural rubber and steel,” Professor Ortiz said, adding that recycled materials have shown similar properties to other isolators, but at a much lower cost.
In his lab, Professor Ortiz and his team demonstrated the elastomeric matrix: a sandwich of recycled fibers and rubber. The largest prototype they have is 62 centimeters in diameter, which looks like a thick tire with no hole inside.
“We made an alliance with a company that is an expert in recycling rubber called Occidental de Cauchos SAS,” explained Professor Ortiz, adding that recycled rubber is more environmentally friendly than other options.
The researchers say they want to encourage the development of a market for isolator systems by companies in the construction sector, as is the case in Chile and Mexico.
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| Photo: Prototype of recycled rubber insulator elements. Credit: Andrew James/NCC-FI/Univalle |
Polyester Fiber Patent
Another innovation of seismic isolators at Univalle is a cheaper and lighter design by using parts made of polyester fibers.Profesor Peter Thomson, director of the G-7 research group, explained that in Colombia and other seismically active countries it is common for hospitals and other critical infrastructure to have insulators, but since they are made of steel, they could be expensive and heavy.
In December 2021, the Superintendency of Industry and Commerce of the Republic of Colombia approved the application of Universidad del Valle and the company Surtidor Industrial SAS for a patent for a “Multilayer Seismic Isolator Made of Rubber Reinforced with Bidirectional Polyester Fibers and Thickness Between 1 .1 and 2 millimeters”.
"It works just like the isolators available today, at an affordable price which means we can use it not only in hospitals, but in a large number of structures, such as bridges and residential buildings," said Professor Thomson, adding that the price and lower weight comes from using parts made from polyester fibers.
Professor Thomson explained that although the work has its origins nearly 20 years ago, it was Professor Johannio Marulanda Casas, current dean of the Faculty of Engineering, who promoted the development that resulted in the patent.
"This idea, we already took up with Professor Marulanda about 8 years ago, we saw that it was a good idea to take this up again and promote it," said Professor Thomson, adding that the next step is to work with the company Surtidor Industrial SAS to commercialize the design. with the goal of producing them on an industrial scale in Colombia.
Professor Marulanda explained that other materials used abroad such as carbon fibers are very expensive, but polyester fibers are not as pricey.
"All these innovations have the purpose of lowering costs, lowering the weight and massifying the process, in which they will be available to all Colombians," explained Professor Marulanda.
Professor Marulanda explained that Univalle research groups have worked on the subject of reducing seismic risk for the last 23 years.
"The Universidad del Valle built the first seismic simulators in Colombia and now, other universities already have... so we are rolemodels and pioneers in this space," said Professor Marulanda, adding that Univalle is building itself up as a pioneer in research, development and innovation on technologies emerging for the mitigation of seismic risks.
Read more from the School of Civil and Geomatic Engineering: Researchers Rehabilitate Thin Concrete Walls With New Techniques
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| Photo: A virtual model of the test frame. Credit: G7 Group/Univalle |
New Test Frame
In addition to new materials, it is crucial to have research infrastructure in this field. To accelerate the development of isolators and train a new generation of researchers, Univalle's engineering faculty is building the first isolator test frame in Colombia.
This frame, which will be built next to the school of civil and geomatic engineering, will have national and international coverage of services for the characterization of different types of seismic isolators.
“There is no structure in the country dedicated to the testing of seismic isolators,” explained Professor Ortiz, adding that until now, the tests of the different isolators had to share another experimental frame with other experiments.
"It will be able to reduce the costs associated with the construction of insulators and developments made in Colombia and it is no longer required to test the insulators in other countries, but rather it is done nationally, lowering the costs associated with it," said Professor Ortiz.
The effort to build it has funding from Univalle.
“The construction of the framework is approximately 660 million COP. The civil work has a cost of COP 440 million (includes structural steel, reinforcing steel, concrete, earthworks) and COP 220 million corresponds to equipment such as a hydraulic pump, actuators, structured wiring and sensors,” said Professor Ortiz.
Video: A simulatio of the test frame for seismic isolators. Credit: Grupo G7/Univalle
“The ARGOS company is going to donate the structural concrete and the SIDOC company is going to donate the reinforcing steel and steps are being taken to achieve the donation of the metal superstructure and the anchoring steel,” Professor Ortiz said.
Seismic Retrofitting of the Engineering Faculty's Buildings
In the years to come, there are even bigger plans to show the wide variety of advances in the field of seismic isolators at Univalle: the retrofitting of 17 buildings of the Faculty of Engineering, beginning with building E48 of the School of Civil and Geomatic Engineering .
“Most buildings have their isolators in the basement, but this project is going to show a method where they are above the roof,” Professor Ortiz said, adding that roof-deck insulators will serve the same role as conventional basement isolators.
In this system, the roof slab is decoupled from the structure and rests on elastomeric seismic isolators, functioning as a tuned mass damper (TMD), a configuration that is facilitated due to the structural types of the Faculty buildings.
Conventional reinforcement techniques for buildings are highly invasive, disrupt construction operations and can be very expensive, but the cost of the roof insulation alternative decreases between 68 and 86% compared to conventional means.
“We hope that this project can show the great potential of retrofitting other buildings,” Professor Ortiz said.
If you would like to contact the researchers or learn more about the projects, write to the Communications Office of the Faculty of Engineering: comunicaingenieria(at)correounivalle.edu.co.
Portal photo: Albert Ortiz's team from Grupo G7. Credit: Andrew James/NCC-FI/Univalle
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