Axial load biaxial moment interaction (PMM) diagrams for shallow foundations: Design aids, experimental verification, and examples. (15th June 2020)

• Record Type: Journal Article
• Authors: Galvis, Francisco A.; Smith-Pardo, J. Paul
• Is Part Of: Engineering structures. Volume 213(2020)
• Publication Date: 2020-06-15
• Subjects: Design aids -- Biaxial capacity of shallow foundations -- Performance-based design -- Limit analysis -- Soil-structure interaction; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2020.110582
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: Design aids are developed to estimate the coupled vertical load and biaxial moment capacity (PMM) of shallow foundations. Developed equations are shown to be a generalized version of Meyerhof's equivalent width concept. The biaxial moment capacity of shallow foundations is symmetric with respect to half of the concentric bearing capacity. Simplified equations are shown to provide reasonable estimates of measured biaxial capacities of shallow foundation models. Abstract: This paper presents the development of design aids and simplified closed-form equations to estimate the coupled vertical load and biaxial moment capacity (PMM) of solid and hollow rectangular and circular shallow foundations as limited by bearing strength of the supporting soil. It is demonstrated that the resulting simplified equations are generalized versions of the widely accepted equivalent width concept proposed by Meyerhof nearly seven decades ago. The formulation can be used in soil-structure analyses where foundation strength influences the seismic response of bridges or buildings. Whether the design philosophy is to capacity protect the foundations or allow rocking and energy dissipation through soil yielding, the proposed formulation and charts allow sizing shallow footings in an expedite manner and using a pocket calculator. Results from four experimental programs comprising over fifty scaled foundation models under biaxial loading are included to show that the proposed simplified equations are useful to reasonably estimate the measured capacities. In addition, two examples are presented to illustrate the versatility of the formulation and ease of implementation.