Design Methodology for Multi-Facetted, Winged Steel Foundations-Paper

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The paper presents a design methodology for multi-faceted steel foundations with lateral extensions (“wings”), which increase resistance to compression, uplift, torsion, and lateral loads. The foundation geometry can be tailored to project loads and subsurface conditions, while potentially reducing excavation, soil disposal, and installation time.<br /><br />The methodology combines finite-element (FE) modeling of the steel structure with nonlinear modeling of soil response. An Excel pre-processor generates STAAD.Pro models for user-defined foundation shapes, wing configurations, embedment depths, top plates, loads, and soil profiles. Soil properties from site investigations and laboratory testing are used to develop nonlinear load–deformation curves; these are represented in the model by lateral compression-only springs.<br /><br />Full-scale tests in Pennsylvania evaluated two-, three-, and four-wing foundations under compression, uplift, and lateral loading. Measured uplift capacities were 32.4, 113.8, and 70.0 kips, respectively. Maximum lateral groundline moments reached approximately 1,000, 1,400, and 1,300 kip-feet, with lateral displacements below 1.5 inches. The authors note that further testing is needed to establish full lateral-moment capacity curves.<br /><br />The methodology was applied to two projects: foundations for highway camera poles and digital signs in Louisiana, and more than 50 transmission-line foundations in Texas. Both projects were successfully constructed, with typical installation times of 10–15 minutes per foundation. The Texas project also demonstrated installation near utilities and in developed areas, with vibration monitoring generally showing acceptable particle-velocity levels.<br /><br />The authors conclude that the modeling tool supports efficient, site-specific design and adjustment to changing soil conditions, loads, and geometry. They recommend continued development of the model and further guidance on monitoring, vibration thresholds, foundation condition, and locating underground utilities.

Keywords

steel foundations

multi-faceted foundation

lateral extensions

finite-element modeling

soil-structure interaction

uplift resistance

lateral load capacity

nonlinear soil response

STAAD.Pro

foundation installation