Tearing Down Walls For Science in Cali, Colombia

Photo: The experimental team at the School of Civil and Geomatic Engineering. Credit: G-7 research group

In a high-ceilinged hall filled with machinery, a team of experts examines the cracks and damage in a reinforced concrete wall; but this is not an archaeological expedition or a forensic investigation, it is an experiment by research engineers from the Universidad del Valle, who are in search of clues of how to prevent real-world disasters. 

That same morning of September 13, 2021, the wall was intact, installed in a test frame, showing the typical characteristics of the thin walls of reinforced concrete that are common in buildings in Colombia and throughout Latin America. 

The researchers used multiple sensors and two high-resolution digital cameras to take photos every 10 seconds, over the course of five to six hours, as the wall struggled along to its inevitable breaking point. 

Tearing Down The Wall

Roger Ortega, is a PhD student at the School of Civil and Geomatic Engineering, of the Universidad del Valle in Cali, Colombia, and was in charge of the Structural Engineering test, at the Test Frameworks for Homologations (MaP-H) Laboratory, as part of the Seismic, Wind, Geotechnical and Structural Engineering research group (also known as G7). 

"What we are doing here is testing a thin, reinforced concrete wall, built on a real scale, representative of a wall on the first floor of a 10-story building," he said, adding that they used hydraulic actuators to simulate a seismic event and the vertical load that the wall would be expected to have in a real building. 

"In this way we can simulate the displacements to which the wall could be subjected, and evaluate its resistance, how it fails and rotation capacity," he explained, "During the test time, which can be several hours, we can evaluate the damage process, record displacements and deformations locally, and detect, using the digital image correlation technique, the formation of cracks, even before they can be observed with the naked eye.”

Photo: The wall, after the experimental trial on September 13, 2021. Credit: G-7 research group

Important for Cali, Colombia 

The seismic events of recent years in Colombia have demonstrated the importance of the work carried out by researchers from the Universidad del Valle on the displacement and resistance capacity of one of the most used construction systems in Colombia and Latin America. 

For now, Ortega said, “the imaging technique with the cameras is only for research, it is not for the inspection of cracks in real time in a building... but this would be possible with other damage assessment techniques."  

“The research is focused on evaluating a proposed reinforcement for the thin, reinforced concrete walls of existing buildings. There is evidence that some of these buildings, in an area of high seismic threat, could suffer significant damage ”, he explained. 

Ortega says that Cali, where the Universidad del Valle is located, is the city in Colombia with the highest number of inhabitants in an area of ​​high seismic threat, and there are many buildings with this construction system, therefore, it is important to investigate the capacity of these walls and alternatives to reinforce them, if necessary. 

The seismic events of recent years have highlighted the need to evaluate current structural systems, new forms of reinforcement, and implement technologies to detect damage or unwanted behavior, before a disaster strikes. 

On June 24, 2021, 98 people were killed when a 12-story residential building collapsed in Miami, Florida. US authorities are still investigating the role that the long-term degradation of some of the reinforced concrete structural supports played in the disaster. 

Colombia has had its own structural disasters in reinforced concrete buildings. On October 12, 2013, an apartment building in Medellín collapsed and killed 98 people.

Photo: Peter Thomson, G7 Group Director, Credit: Andrew James / NCC Univalle

Capacity To Build 

"This is our fifth experiment of this type and the important thing is that this allows us to develop the capacity to carry out increasingly complex tests," Ortega said, adding that Univalle is one of the few universities in Colombia with the capacity and infrastructure to carry out these tests.

"At an academic level, the most important thing is that we are training undergraduate and graduate students, as well as laboratory personnel, which strengthens the research group and will allow future progress in continuing the research and develop new projects," he said. 

Peter Thomson, Director of the G7 Group, said this was a demonstration of the local capacity that was being built within the group. 

"Other commercial solutions in the markets can cost tens of thousands of dollars," he said, "What makes us proud here is that we can get solid results with a couple of good digital cameras, existing experimental setups, and all of the knowledge we've built up here at Univalle."