Launch of the AIS 410-23: Colombia’s first national regulation for evaluating and reducing risk in informal masonry housing

The Colombian government has tried to reduce the seismic risk in the housing sector since the 1983 Popayan earthquake, through the implementation of the first seismic code in 1984. The Colombian Association for Earthquake Engineering (AIS) is a non-profit that develops the proposals for mandatory regulations for earthquake-resistant constructions in the country.

Since the approval of the first seismic code in 1984 and with the updates of the regulation, the reduction of vulnerability in the formal residential sector has become a reality. However, informal self-construction continues to expand in the country due to specific socio-economic circumstances.

Several local studies show that as much as 65% of the existing housing stock has been constructed informally in Colombia and can be considered vulnerable to hazards. These buildings generally consist of load-bearing masonry systems, un-reinforced, partially confined or confined, constructed using brittle and weak clay or concrete units and cement mortar. They often suffer from structural deficiencies and are built and expanded progressively over time.

To reduce the vulnerability in this type of structure, it would be reasonable to use the Colombian Earthquake-Resistant Construction Code, NSR-10. However, implementation exercises demonstrated that these specifications are difficult to comply with in the case of existing, informal houses. This highlighted the need to define an alternative method for retrofit and vulnerability reduction, developed specifically for the existing informal sector.

In response, AIS, with the support of the nonprofit Build Change has developed the standard AIS 410-23: EVALUATION AND REDUCTION OF SEISMIC VULNERABILITY IN MASONRY HOUSES.

The AIS410-23 regulation contains an alternative engineering method to reduce the vulnerability of existing, informal, masonry houses up to three stories. This standard provides prescriptive solutions for retrofit that are technically feasible and affordable in this specific context and includes guidelines for a progressive approach to vulnerability reduction that might be necessary in scenarios where resources are limited.

On August 1st, 2024, the AIS410-23 regulation was launched, featuring speakers from the Bogota’s Popular Housing Fund, Colombia’s Adaptation Fund, the University “Escuela Colombiana de Ingeniería Julio Garavito”, Nueva Granada Militar University, ONU-Habitat, members of the AIS400 Committee, the Colombian Geological Survey, and Build Change.

The event included two panels that addressed key questions: How can resilient housing be promoted within the national public policy to reduce structural vulnerability? And how can the existing home improvement programs be enhanced to incorporate disaster and climate change resilience? The discussions considered a evaluation of the existing regulations, various programs financing schemes, the use of technological tools, and the need of research to improve and expand current retrofit strategies. Additionally, a talk was dedicated to acknowledging the contributions of engineer Luis Guillermo Aycardi for his commitment to retrofitting informal housing in Colombia.

The launch of the AIS410-23 regulation marked a significant achievement and sets a precedent for other countries in Latin America facing similar challenges. In addition, this regulation will be implemented in Colombia’s home improvement programs with a structural approach to reduce structural vulnerability at scale.