Given the risk it represents for residents of homes built on columns or stilts that are not resistant to earthquakes, the owners of that type of residence can still modify the structure of their homes to strengthen them in the face of a seismic event of greater magnitude.
According to the engineer Ricardo López, expert in the construction of earthquake resistant structures of the Mayagüez Campus (RUM) of the University of Puerto Rico (UPR), the only way to protect houses and structures on stilts is to build reinforced concrete walls between the columns that support the weight of the residence.
“Basically, what is proposed is to build reinforced concrete walls on the first floor to strengthen that floor, which is the danger; make walls on the first floor and join them to the columns that are already made, ”explained the engineer.
López’s recommendations are part of a booklet entitled “Houses on stilts” prepared together with Dr. José Martínez Cruzado, also an RUM expert, focused on how to repair houses built on columns to strengthen their resistance to earthquakes.
“We have done studies previously in the university campus of Mayagüez and we have pointed out many times that there are many structures, houses and columns in Puerto Rico that cannot withstand a strong earthquake because they have not been designed according to the most recent (Construction) Codes” explained the engineer.
These concrete walls must be constructed in such a way that they withstand the weight of the house without depending on the columns.
“As in the (Construction) Code of Puerto Rico specifies what are the design forces for earthquakes, one calculates the walls so that it has sufficient thickness and reinforcement to resist those effects, including the weight of the house on it,” said the engineer.
A strong tremor of magnitude 5.8 was recorded on Monday morning south of Puerto Rico, an event that caused structural damage in several municipalities in the region.
“The photos I have seen are mostly structures that were raised in columns and as you can see the structure already on the floor, it is difficult to see what type of columns they had,” López said of some affected residences in the south.
The engineer also observed images of residences with cracks in block walls, but such damage, he explained, is common if the structure is close to the area where a strong earthquake occurs, as was the magnitude 5.8 reported this morning. “It is not a structural problem, it is repaired and it is not a risk of collapse,” he said.
The commissioner of Negotiated for Emergency Management and Disaster ManagementCarlos Acevedo, acknowledged yesterday that one of the concerns is that in Puerto Rico there are about 150,000 homes nestled on stilts and that they would be at risk of collapsing if a major earthquake occurs.
The engineer López indicated that one of the problems is that people continue to build houses without the review of an engineer or architect who is skilled in determining whether or not the structure is resistant to earthquakes.
“The recommendation is that they comply with the government permit procedure, which includes the design and inspection of engineers or licensed architects who are knowledgeable,” said the RUM expert.
“That at least they hire a structural engineer or an architect to review it (the structure), if it has a plan; if it does not have a plan, I think they should reinforce it, because if it does not have a plan, it seems to me that they have built it informally, ”said the engineer.
