Field measurements of laterally loaded drilled shafts

Horizontal wind forces and the resulting overturning moments represent a large portion of the loadings on the foundations of traffic signal control structures. Traditional design procedures (AASHTO, 1985) based on pseudo-static limiting equilibrium analysis often produce drilled shafts whose diameters and lengths increase very rapidly with increased lateral loads. Deflection analysis can now be incorporated into methods for improved design of laterally loaded drilled shafts. However, uncertainties remain relative to the characterization of the soil response to the applied loadings, including the effects of soil-structure interaction. This paper describes field performance measurements of full scale laterally loaded drilled shafts which support traffic signals. The measurements were made with the objective of developing improved design methods.