Date of Award

Spring 2021

Document Type

Open Access Dissertation

Department

Civil and Environmental Engineering

First Advisor

Juan M. Caicedo

Abstract

High performance materials have enabled engineers to design civil structures with lower dead loads. However, lower dead loads result in a higher live-to-dead load ratio and the possibility of excessive vibrations due to human loading. Classical methods that have been used to study this human-structure interaction (HSI) model the person as a mass-spring-damper (MSD) system. While these models are often able to represent the dynamics of the system, the human body is a more complex, dynamic system. For example, MSD systems cannot add energy to the overall human-structure system; therefore, they do not allow for the incorporation of excitation that is provided by the person.

This study extends a controller theory based model to evaluate the human-structure-interaction (HSI) problem. Previous research used a proportional, integrative, and derivative (PID) controller model for a person standing with bent knees. This work extends this idea to a person bouncing or performing short movements up and down by bending his or her knees at a frequency provided by a metronome. Previous research has also considered the input to the human-structure system as a force applied to the structure. This work considers the beat produced by a metronome as the input to the overall human-structure system. The force applied to the structure is modeled as the output of the human sub-system, while the structure's acceleration is fed back into the control human system. Experiments that were performed at the University of South Carolina, which used a flexible platform that behaved as a single degree of freedom (SDOF) system, were used to test the model. A force plate was installed in the platform to measure the forces exerted by the person on the platform as he or she moves. Model parameters and their corresponding uncertainty were quantified in a probabilistic fashion using Bayesian inference with the forces from the force plate and the acceleration measurements from the structure as observations. Model performance was evaluated by comparing probabilistic predictions with force and acceleration measurements obtained experimentally. When designing a building, the dynamic load on a structure due to human activity must be known. This study allows for the creation of a mathematical model that predicts the dynamic load of person bouncing on a flexible structure. This type of mathematical model will have direct application in the field of civil engineering. With this model, civil engineers will be able to predict the dynamic load of a person, which is the live load on the structure, and design a building based on this prediction.

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