The Project to Replace Non-ductile Buildings
In any major city there are countless buildings that have not been retrofit to 21st century sustainable construction standards. Non-ductile buildings refer to concrete or reinforced concrete structures that lack flexibility. These non-ductile buildings that were constructed without the knowledge of earthquake safety may be toppled by severe seismic activity.
Recent Earthquake Evidence
A devastating 7.8 earthquake hit Kathmandu, Nepal in 2015, killing over 4,000 people. The quake was so strong it is believed to have lowered Mount Everest slightly, causing an avalanche, according to NASA. The area’s infrastructure was damaged, leading to massive power outages. Many non-ductile reinforced concrete buildings collapsed, which has been the pattern around the world. In the United States, these type of structures began getting phased out on the west coast in the 1950s and by the 1980s became scarce among new buildings.
More Flexible Buildings
The key to avoiding massive damage to a building is in its construction. Modern techniques using closely spaced steel ties in columns that provide additional reinforcement reduce the odds of a building collapse. Older buildings can be retrofitted to create safer conditions, which is an alternative to tearing down the entire structure. The cost of retrofitting, however, can be expensive, which is why not all old building owners are on board with the process. As a result, contractors are looking for new ways to retrofit without disrupting businesses.
Georgia Tech conducted earthquake simulation tests on three different retrofit construction methods to find out which one could withstand the most vibrations. The result was that all three modern models performed well, whereas a non-retrofit control model was on the verge of collapse. The university is looking deeper into these shake tests to provide retrofit guidelines to the International Code Council (ICC). One of the proven materials that can pass the shake test is a bendable nickel titanium alloy that behaves like a spring.
The Future of Retrofitting
Clearly, the United States and other nations have been moving away from non-ductile buildings and seek to modernize those that were built by old standards prior to the fifties. It will be up to developers and building owners to decide what type of design or retrofit their structures need.
Several cities have started to mandate retrofitting of certain old buildings, such as in San Francisco, which has a goal by 2020 to retrofit structures with wooden frames of five or more units and “soft” first stories. Los Angeles is considering offering tax credits to building owners who agree to retrofit. A primary strategy for earthquake safety across all cities is preparedness, which includes proper construction built from flexible materials, particularly for schools and hospitals.
Saunders Seismic has decades of experience doing structural repairs and seismic retrofits to commercial buildings throughout the west coast. We’re up-to-date in all the latest earthquake safety techniques, and can help you identify those modifications that will help your business better stand up to the stress of an earthquake. Contact us to learn more.