On Monday, July 10, 2006, a passenger car en route to Logan International Airport was crushed when a section of the I-90 connector tunnel's suspended concrete ceiling fell onto the vehicle. One of the passengers was fatally injured.
The National Transportation Safety Board determined that the probable cause of collapse was the use of an epoxy anchor adhesive with poor creep resistance.
Epoxy is a polymer and its stiffness is time and temperature dependent. If a load is applied suddenly, the epoxy responds like a hard solid. But if the load is then held constant, the molecules within the polymer may begin to rearrange and slide past one another, causing the epoxy to gradually deform in a process called creep. The epoxy used in the tunnel had poor creep resistance.
According to the NTSB, the use of an inappropriate epoxy formulation resulted from a general lack of understanding and knowledge in the construction community about creep in adhesive anchoring systems.
Among its recommendations, the agency urged ASCE to emphasize within the profession the need to assess the creep characteristics of adhesive anchors before those anchors are used in sustained tensile-load applications.
In response to this recommendation, ASCE formed the ASCE Task Committee on NTSB Recommendations.
The committee members are:
David Nash, Chair
BE&K Federal Group,LLC
Gene Balter, P.E., F.ASCE
HDR Construction Control Operation
Marco Legaluppi, P.E., M.ASCE
Rayford W. Jenkins, Jr., P.E., M.ASCE
Whitman Requardt and Associates, LLP
Jim Roskie, P.E., M.ASCE
Construction, Weeks Marine, Inc
Clark Foundations, LLC
John F. Silva, S.E., M.ASCE
Hilti North America
Read the white paper report.