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Sponsor: Texas Department of Transportation

PI: Michael Engelhardt
Co-PI’s: Todd Helwig, Eric Williamson, Lance Manuel

High Mast Illumination Poles (HMIPs) are used throughout Texas and the U.S. to provide lighting along highways and at interchanges. There are currently about 5,000 HMIPs in Texas, varying in height from 100 to 175 ft. In recent years, a number of collapses of HMIPs have been reported in other states. These collapses have been attributed to fatigue failures at the HMIP shaft-to-base plate connection.

No collapses of HMIPs have been reported in Texas. However, recent studies have shown that many galvanized HMIPs in Texas have pre-existing cracks at their shaft-to-base plate connection, most likely caused by the galvanization process. Research has also shown that pre-existing cracks may significantly reduce the fatigue life of galvanized HMIPs. The potentially poor fatigue performance of galvanized HMIPs with pre-existing cracks in Texas is a significant concern as collapse of an HMIP represents a safety hazard. In addition, inspection, monitoring, repair, and replacement of HMIPs may be a significant cost, particularly in light of the large number of HMIPs in Texas. Because of the safety and cost concerns, better methods are needed to identify the remaining fatigue life of in-service TxDOT HMIPs with pre-existing cracks.

This project will generate data and information to support a probability-based assessment of the remaining life of pre-cracked HMIPs. Laboratory fatigue tests will be conducted on pre-cracked galvanized HMIPs. In addition, field data will be collected and additional analyses will be conducted to characterize wind response of Texas HMIPs. Field and laboratory studies will be supplemented by finite element studies simulating the global and local response of pre-cracked HMIPs. The results of the laboratory data, field studies, and analytical studies will be combined in a reliability-based framework to provide a probabilistic assessment of the fatigue life of in-service pre-cracked HMIPs. Finally in this project, additional information will be developed on options for mitigating risk associated with cracked HMIPs, such as increased inspection and monitoring, repair techniques, and methods to reduce vortex shedding.