Design of prestressed, fabric-formed concrete beams

Abstract

Fabric forms and prestressing are both technologies for concrete structures that allow for less material to do more work. This thesis seeks to assess the feasibility and performance of fabric formed, prestressed beams with a keyhole cross-section, while varying parameters such as concrete strength, loading, beam depth, and prestressing force. They are designed for flexure via a sectional method, starting with the critical midspan section, and each section is iterated in an effort to minimize the beam weight. Beam strength and deflections are determined and once met, they are compared to more traditional prestress designs. Such beams are found to be governed primarily by strength criteria, as deflections are found to be minimal. These fabric formed beams can use nearly an identical amount of material as conventional I-beams with a constant cross-section, while requiring a higher prestressing force. Prestressed fabric formed beams are less efficient than an I-beam section, but should not be discounted as a viable element, because of their aesthetic appeal and further potential for optimization.