Structural and Civil Engineering Curriculum

Shallow Fdn

Module from the Structural and Civil Engineering Curriculum curriculum.

Module 3 - Shallow Foundations · Learning Objectives · 1. Size spread footing: B = P/q_a (simplified square), check eccentricity · 2. Design combined footing when columns close together · 3. Apply mat foundation when column spacing < 3 * footing width · 4. Design ringwall for tank foundation (API 650 App B) · 5. Verify soil pressure does not exceed allowable under all load combos · Shallow Foundation Selection Matrix

Load (kip)	Soil Bearing	Footing Type	Typical Dim	Reinforcement	Notes
5-20	>2000 psf	Single spread	3x3 ft	Mat or grade	Small pumps
20-100	>2000	Single spread	5x5 ft	Both ways	Medium pumps
50-200	>3000	Combined 2-column	8x4 ft	Both ways + hooks	Tower
Large (300+)	>3000	Mat	Continuous	Two-way	Large equipment
Any tank	Per soil	Ringwall	Ring B=3-6 ft	Hoops	API 650 App B
Tall & slender	Any	Octagonal	Sized for OTM	Top + bottom	Stacks, columns

Source: Structural_Civil_Engineering_Curriculum_v1.xlsx · Sheet: Shallow Fdn

© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.

Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.