Date of Award

Summer 8-22-2019

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

William Davids

Second Committee Member

Edwin Nagy

Third Committee Member

Roberto Lopez-Anido

Abstract

Rapidly erected shelters are often required due to military needs, natural disasters, and humanitarian crises. Creating shelters quickly can be difficult due to the amount of labor required for erection. One popular class of rapidly erected shelters consists of parallel, inflatable fabric arches that spring from the ground and are covered with tent fabric. However, while quickly erected, these structures require large capacity air compressors, lack the protection provided by a rigid-walled shelter, and usable interior space is compromised by the shape of the arches. The focus of this research is the exploration of a hybrid inflatable-rigid wall structure that will overcome some or all of these issues. A central question is whether inflatable arches can be used to drive erection of such a structure as part of a mechanism. Semi-circular, inflatable arches were clamped to create the necessary arch span and inflated to heights below their full rise, and the vertical force required to resist additional arch rise was measured as a function of inflation pressure to assess the lifting capacity of one arch. Testing revealed that inflatable arches have a high tendency to bend out-of-plane and the shape that they take prior to inflating to their full rise can significantly effect their lifting capacity. Additional tests were conducted to assess the ability of a single arch to erect folding, exterior rigid walls. These tests showed that a single arch was able to erect a structure with a folding wall panel on each side weighing 420 N at a modest inflation pressure of Full Public Release, CCDC SC, PAO # U19-1432 about 110 kPa, well below the normal operating arch pressure of 344 kPa. Finite-element analyses of the inflated arches were conducted using nonlinear inflatable beam theory to explore the load capacity of the erected structure and assess its gravity load capacity relative to a conventional, soft-walled arch shelter. These analyses indicate that the arch structure with rigid walls has a gravity load capacity slightly higher than that of a conventional soft-walled arch for inflation pressures ranging from 137 kPa to 344 kPa. Future research on this structure should focus on refining estimates of arch lifting capacity during inflation, exploration of alternative forms of hybrid rigid-airbeam structures, and refining finite element models used to determine the inflated structure’s capacity.

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