Cyclic Behavior of Screen Grid Insulated Concrete Form Components

The principle of sustainability in the built environment has become much more significant in the past decade, resulting in a push to develop building systems that are more energy efficient, durable, and use fewer natural resources. For residential and light commercial buildings, insulated concrete forms (ICF) have enjoyed increasing popularity for their ability to meet these new demands. ICFs are a stay-in-place concrete formwork system for building structural walls that are also highly insulated, among other benefits. Screen-grid ICFs (SGICF) are a small subset of ICFs that tend to use less concrete than standard ICFs and are sometimes made of recycled materials. These traits make SGICFs attractive, but there is a lack of understanding of their structural characteristics due to their irregular internal concrete structure. Because of this, structures using SGICFs are limited to heights no higher than two stories. Further study should show whether SGICFs structures can safely built to greater heights. This investigation studied two types of SGICFs at a component level in order to gain understanding of their lateral force and drift ratio capacities under cyclic loading. Several variables, including steel reinforcement details, the type of concrete, and the presence of the forms, were altered to measure their impact on the performance of the systems. Test results suggested that the ICF formwork increased lateral strength by up to 100% and lateral deformation capacity by up 60% when compared to identical specimens tested with the formwork removed. Results also showed that confinement of the cement, ii either by mesh hoops, spiral wire, or fiber-reinforced concrete improved the drift ratio at failure up to 500% when compared to specimens with no confinement material. Computer models were created to gauge their ability to replicate the behavior of the experimental test results. The models typically overestimated the lateral load resistance of the samples by 50%-100%, and even more in some cases, depending on the reinforcement. The models were not reliable in determining the drift ratio at which the sample was considered to have failed. In some cases the model failed at 50% lower lateral deformations than the test specimen, while in others the model did not fail at all. Future studies should explore refinements of the models to increase their accuracy and usefulness, as well as accounting for the contributions do to the form material. Future studies should also include using spiral wires, mesh hoops, or fiber reinforced concrete in full-scale walls to verify their efficacy in improving overall wall performance. iii ACKNOWLEDGEMENTS Thank you to my advisor and thesis chair, Dr. Peter Dusicka, for your support and input throughout my tenure at PSU. Your direction and suggestions proved challenging and invaluable, and undoubtedly improved the quality of my studies and research. Thank you to my remaining thesis committee members, Dr. Franz Rad and Dr. William Fish, for the excellent suggestions for improving the quality of this paper. Thank you to all the iSTAR dwellers and especially to Thomas Bennett for all the invaluable help over the past two years. My research would have been impossible without all your contributions. Thank you also to Apex Construction Systems, Shelterworks Ltd., and Ross Island Sand & Gravel for the donation and delivery of the ICF forms and concrete used in this research. Thank you to my parents, whose encouragement and support at every stage of my life proved to be the foundation and catalyst for achieving what I have. Lastly, thank you to my wife Mica for your inexhaustible strength and patience. This would have not been possible without your love and encouragement. And of course, thank you to my son Elliot for the experience of the irrepressible joy, wonder, and energy of toddlerhood.