Publication Date

8-2022

Date of Final Oral Examination (Defense)

6-17-2022

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Civil Engineering

Department

Civil Engineering

Supervisory Committee Chair

Bhaskar Chittoori, Ph.D., P.E.

Supervisory Committee Member

Nick Hudyma, Ph.D., P.E.

Supervisory Committee Member

Robert Hamilton, Ph.D., P.E.

Abstract

It is not easy to find a more efficient foundation system than the roots of a tree. Trees create a vast three-dimensional network of roots to support and anchor the critical above-ground trunks, leaves, and limbs. In this work, investigations are made for the feasibility of imitating such a technique and creating similar networks to support civil infrastructure, particularly those subjected to moment loads such as traffic signal posts. Some of the raised questions were: Is it feasible to have a shallow tree root-based foundation system to provide the same capacities as conventional foundation alternatives? If this is feasible: What would be the ideal depth of the Root Foundation System? How far should the roots extend to provide comparable support to a conventional deep foundation system? What diameter should the root bulb of the configuration be? How far should a vertical shaft extend into the ground?

Hence, the main objective of this research is to identify and test the most effective Root Foundation System geometric configurations that can provide a similar capacity as a conventional foundation for traffic signal posts. Finite element model simulations on 54 different root-based foundation models show potential for replacing the conventional drilled shaft foundation for traffic signal posts. The conventional foundation was also modeled and produced a 0.528 mm deflection. Whereas some of the best performing root foundation models achieved 0.23 mm. By comparing the resulting deflection of the conventional foundation model to the deflection of the root foundation models, the best performing root foundation models were constructed from steel and physically tested. The root foundation models were then calibrated to predict the performance of root foundation models. Results show that the RFSs with half the length and diameter of conventional deep foundations (for traffic signal poles) were able to provide more than four times the lateral load capacity compared to the control sections. This shows that RFSs have excellent potential to replace the conventional deep foundation alternatives used to support traffic signal posts. The economic and environmental impacts due to the root-inspired foundation systems could be tremendous owing to the reductions in the material requirements.

DOI

https://doi.org/10.18122/td.1973.boisestate

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