Improving Earthquake Resilience: Reinforced Concrete Buildings Under Examination

Shake, rattle, and perhaps roll – these thoughts occupy the minds of a team of young engineers hailing from Tufts University. They are currently engaged in an extensive assessment of buildings constructed with reinforced concrete frames and masonry infill walls to determine how they perform in the face of an earthquake. Their ambitious objective is to push a building in El Centro, California, to the brink of collapse through a series of rigorous tests.

Given California's status as an earthquake-prone state, these tests have far-reaching implications. The results will be instrumental in enhancing the accuracy of analytical models used by engineers to assess the seismic safety of similarly constructed buildings, irrespective of their location. This research is particularly significant because the chosen building has already sustained severe damage from prior earthquakes and is slated for demolition.

The selected building has never undergone retrofitting with materials like carbon fiber reinforced polymers (CFRP). Notably, CFRP systems, such as those developed by HJ3 Composite Technologies, offer the capability to seismically retrofit a wide range of structures, including residential, civil, commercial, and industrial. By wrapping concrete, steel, masonry, or wood structures in carbon fiber, the high-tensile strength of this material effectively withstands the live loads generated by seismic forces. Structures can be retrofitted to conform to changes in seismic codes, regardless of whether an earthquake has occurred in the past or not.

The Tufts University engineers have structured their project into two main phases. Initially, they assess the building's existing condition and collect pertinent data. Subsequently, they will mount an "eccentric-mass shaker" on the building's roof. This specialized spinning device will create top-down vibrations to replicate the pulsating tremors of a genuine earthquake. Computers will record data from sensors strategically placed throughout the building.

Thousands of structures in earthquake-prone regions, including Los Angeles, San Francisco, the northwestern United States, New Zealand, the Mediterranean, and Latin America, are at risk if they haven't been retrofitted to adhere to current seismic codes. These structures could significantly benefit from the insights garnered in this study, and they could also find invaluable solutions in rapidly deployable, lightweight, high-strength alternatives such as HJ3's structural strengthening systems.

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West Commercial Avenue building in El Centro, CA. (Credit: Babak Moaveni, Tufts University)

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