Abstract:
The proposed talk will present an overview of the current state of practice of coastal US DOT's regarding foundation systems for coastal cantilevered highway signs and mast arm traffic signals. This topic is of interest to coastal state highway agencies that have to design safe and cost-effective highway signs and traffic signals in coastal environments that are exposed to high wind loading demand and often have poor geotechnical conditions. The presentation will summarize design procedures of several coastal departments of transportation to highlight the needs, challenges, and opportunities in this SSI problem.These types of structures in coastal environments can be exposed to large loading demand due to high wind speeds that can result in large complex loading involving combined lateral and torsional loads. The design challenges is further affected by the presence of poor soil conditions with high water tables commonly existing in coastal environments. The presentation will include a detailed description of the failure of several drilled shaft foundations that were supporting cantilevered coastal highway signs in Puerto Rico affected by Hurricane Maria. Hurricane Maria was classified as a strong Category 4 hurricane on the Saffir-Simpson hurricane wind scale before making landfall in Yabucoa, Puerto Rico, U.S.A. on Sept. 20, 2017. The case histories will compare different design methods and highlight challenges and opportunities for improvement.