Date of Award
Doctor of Philosophy
Civil, Construction, and Environmental Engineering
Insulated concrete sandwich panels are designed to provide an energy-efficient and fast construction solution. They typically consist of two concrete wythes separated by an inner layer of insulation. Recently, Fiber-Reinforced Polymer (FRP) has been used as shear connectors to connect the two concrete wythes, which is expected to reduce thermal bridging and increase strength-to-weight ratio. To study the effectiveness of FRP shear connectors, a nonlinear Finite Element (FE) model was constructed, and its accuracy was proven through good correlations between the FE and existing test results. The FE model was further used to conduct a parametric study by varying the stiffnesses of the shear connectors. Different methods to calculate DCA were evaluated. It was concluded that FRP connectors can provide enough strength, although they have lower stiffness compared to steel, resulting in partial Degree of Composite Action (DCA).
Motivated by the promising results from the FE study on the sandwich panel, this dissertation aims to develop a multifunctional photovoltaic (PV) integrated insulated concrete sandwich (PVICS) panel, through integrating photovoltaic (PV) cells on the top of the panel. The PVICS panel can act both as an active energy system by harvesting solar energy using the solar cells; and a passive energy system, where the energy saving is provided by the insulation layer, similar to a traditional insulated concrete sandwich panel. The combined active and passive energy system can achieve a zero-carbonate building system.
A combined experimental and FE study on a prototype PVICS panel was conducted to prove the concept. An FRP shell was manufactured as the stay-in-place formwork for the sandwich panel. Solar cells were attached to the exterior surface of the FRP shell using an innovative co-curing scheme. Polymer concrete was applied to the inner surface of the FRP shell to enhance the bond between the FRP and concrete. In addition to acting as an interface to bond solar cells and concrete, the FRP shell can provide a confining effect, and act as shear connectors and reinforcement to improve the structural performance of the PVICS panel. It was found that FRP shear connectors can provide nearly 85% DCA and solar cells worked properly, which proves the concept of PVICS. Furthermore, two issues were identified which need further investigation to properly design the PVICS panel: (1) the performance of the solar cells under different strain states; and (2) the non-uniform strain distribution across the width of the panel, known as shear-lag effect.
To address those two issues, the performance of thin-film amorphous silicon (a-Si) and perovskite solar cells were investigated under different strain states. Compression and tension tests were conducted on a-Si solar cells bonded to FRP plates and tension tests were conducted on perovskite solar cells attached to glass substrates. J-V characteristic curves were measured at different strains until the samples failed. It can be concluded that there are strain thresholds for both compression and tension for a-Si solar cells, which worked properly below the thresholds but degraded rapidly once the thresholds were passed. Perovskite solar cells are more ductile, which can withstand a strain of 3%. No degradation of the performance was observed before the substrate failed.
To study the shear-lag effect, an analytical solution is developed where the partial DCA and boundary conditions from various configurations of the flexible shear connectors are considered. The effective width, an important parameter to describe the shear lag effect, is defined. The analytical model is then verified through close correlations between FE and analytical results for an insulated concrete sandwich panel with FRP shear connectors. A parametric study is finally conducted using the analytical model to study the effects of deck stiffness and aspect ratio on the effective width. The results from this study can be used for the design of insulated sandwich panels. Similarly, the analytical solution could also be used to study the partial DCAs for FRP deck-on-steel girder system, as illustrated by a combined analytical and FE studies on the system.
Yossef, Mostafa, "Development of a multifunctional photovoltaic integrated insulated concrete sandwich panel" (2017). Graduate Theses and Dissertations. 15649.