Improving Steel-CLT Composite Floor System

Abstract

As sustainability becomes increasingly essential in construction practices, the incorporation of concepts such as circularity and material efficiency are more required than ever. The present research investigates how these concepts can be effectively applied to Steel-Cross Laminated Timber (CLT) composite floor systems in order to promote more sustainable construction methods, specifically reducing carbon footprint. The findings are intended to benefit practicing engineers and designers, as well as lay the groundwork for future academic research and innovation in sustainable construction.
WSP developed the baseline steel-CLT composite floor system, which bonds composite materials using shear studs and grout . However, this design restricts disassembly at the end of its lifecycle, posing challenges that limit its potential for reuse in subsequent applications. In addition to that limitation, while the system was validated via laboratory push-out tests, using a standardized CLT configuration across varying spans resulted in material inefficiencies, highlighting the need for additional optimization.
To address the aforementioned drawbacks, this study develops an "optimized design" for a Steel-CLT composite floor system that enhances both circularity and material efficiency. The optimized system, which includes demountable shear connectors, allows for easy disassembly and reuse, extending the life of its components. The study also investigates the optimal CLT configuration and lay-up to maximize material efficiency, demonstrating that adapting the CLT design to the unique characteristics of each composite floor structure (e.g., dimensions, spans, and load requirements) is crucial for optimal performance.
Finally, the baseline- and optimized designs were compared in terms of environmental impact, focusing on a Life Cycle Assessment (LCA) of embodied carbon. This evaluation highlights the environmental benefits of the optimized design, offering valuable insights into how circularity and material efficiency can significantly reduce the carbon footprint in constructions.
Overall, this research transforms the baseline steel-CLT composite floor system from a linear to a circular design, thereby highlighting the significant advantages of circular design principles within the construction industry. By advocating for the broader adoption of circular approaches, this research underscores the potential for creating a more environmentally sustainable future in building practices. In addition to achieving circularity, the study focuses on optimizing the CLT design to enhance material efficiency within the floor system. It also identifies key factors to consider when designing CLT for composite applications, ensuring that the material is used most effectively within this innovative context.
The present paper begins with a comprehensive literature review, which provides the foundational background necessary for the research. This is followed by a detailed explanation of the design rules employed in the structural analysis. Next, the application of demountable shear connectors is discussed, highlighting their role and implications for the steel-CLT composite system. A subsequent chapter delves into the design of CLT panels, emphasizing their dual function within composite floor systems. Both the baseline and optimized floor systems are then presented, with an outline of their structural characteristics and geometric configurations, followed by a rigorous structural analysis. The study proceeds with a comparative analysis, evaluating the structural and environmental performance of both designs. This analysis resulted in conclusions that highlight the substantial role of circular design principles and material efficiency in reducing the environmental impact of construction materials and systems, as well as the crucial role that structural designers can play in advancing the decarbonization of the built environment.