Deconstructable systems for sustainable design of steel and composite structures

According to the U.S. Energy Information Administration, construction and use of buildings consumed almost half of the total energy used in the United States in 2012. Design for Deconstruction (DfD) of buildings was proposed to minimize the environmental impacts and reduce the pollution and waste produced during the construction and demolition of buildings by reclaiming the materials at the end of the service life of buildings. Traditional steel-concrete composite flooring system makes the most efficient use of the two materials, with steel being subjected to tension and concrete resisting compression. However, in this system the concrete slabs are poured integrally with the supporting steel framing systems, inhibiting the separation and reuse of the structural components. The objectives of the proposed research are to develop new structural system concepts for deconstructable steel and steel-concrete composite construction to facilitate DfD coupled with the use of recycled materials in sustainably optimized construction. The proposed system not only maintains the benefits offered by composite construction but also enables disassembly and reuse of the structural components. This dissertation first describes the deconstructable composite floor system utilizing clamping connectors. This floor system is anticipated to be used along with all-bolted construction for the remainder of the structure to facilitate deconstruction. The environmental benefits of utilizing DfD in the design of buildings is demonstrated with the life cycle assessment results of prototype structures. The experimental program for investigating the performance of the system is then introduced. Pushout tests are conducted to quantify the strength and ductility of the clamping connectors and evaluate the influences of the parameters. It is indicated that the strength of the ductile clamping connectors is comparable to that of steel headed stud anchors. In addition, the behavior of the clamping connectors is further validated through full-scale beam tests in which the flexural behavior of the deconstructable composite beams is investigated comprehensively. Combining experimental and finite element analysis results, strength design equations and resistance factors are proposed for calculating the shear strength of the clamping connectors and the flexural strength of the associated composite beams. This dissertation culminates with conclusions and future work.