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Performance of Externally Bonded Fiber Reinforced Polymer Retrofits in the 2018 Cook Inlet Earthquake in Anchorage, Alaska



Siamak Sattar, David Goodwin, Sandra Milev, Jazalyn Dukes, Christopher Segura


As part of the effort to improve the seismic performance of buildings in Alaska (AK), many of the deficient structures in Anchorage, AK were retrofitted—some with externally bonded fiber-reinforced polymer (EBFRP) composite systems. The 2018 magnitude 7.1 Cook Inlet earthquake that impacted the same region offered an opportunity to evaluate the performance of EBFRP retrofits in a relatively high-intensity earthquake. This study summarizes the findings on: (1) the performance of EBFRP retrofitted structures in the Cook Inlet earthquake, and (2) the observations concerning the condition of FRP retrofits from over a decade of exposure in a subarctic environment. A deployment team from the National Institute of Standards and Technology (NIST) in collaboration with the University of Delaware (UD) Center for Composite Materials conducted post-earthquake inspections of EBFRP retrofits in multiple buildings to assess their performance during the earthquake and condition with respect to weathering. EBFRP debonding was documented with infrared thermography and acoustic sounding and the bond quality between EBFRP and concrete was assessed using pull-off tests. Visual inspections showed no major signs of earthquake damage in the EBFRP-retrofitted components. However, evaluation of debonding and pull-off test results suggested that outdoor conditions may have led to bond deterioration between EBFRP and concrete.
Earthquake Spectra


Sattar, S. , Goodwin, D. , Milev, S. , Dukes, J. and Segura, C. (2021), Performance of Externally Bonded Fiber Reinforced Polymer Retrofits in the 2018 Cook Inlet Earthquake in Anchorage, Alaska, Earthquake Spectra, [online],, (Accessed May 22, 2024)


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Created August 11, 2021, Updated October 14, 2021