Michael D. Lepech

For Teachers

Sustainable Integrated Materials, Structures, and Systems (SIMSS) Design Approach

The Sustainable Integrated Materials, Structures, and Systems (SIMSS) design approach guides all research within this research group.  Each research focus or project fits within this broad philosophy for the design, operation, and management of sustainable engineered systems.  In the sustainable built environment specifically, this includes the design of new building materials, building systems, neighborhoods, and infrastructure networks such as transportation, drinking and wastewater, telecommunications, and energy.

The SIMSS design approach recognizes the interdependencies between materials design, structural engineering, and system management, along with the impacts each of these disciplines has on achieving more sustainable engineered systems.  The impacts are quantified through life cycle assessment (LCA) techniques.  Design changes at any scale (materials, structure, or system) have non-linear effects on overall sustainable performance.  SIMSS quantifies these effects and enables comprehensive design for more sustainable built environments and other societal systems.

Sustainable Materials Engineering

The introduction of new, designable composites allows for the introduction of more sustainable materials throughout the built environment.  This work has focused on the development of more sustainable cement-based composites through the introduction of industrial waste streams into high performance fiber reinforced cementitious composites (HPFRCCs) which undergo strain-hardening under uniaxial tension.  Engineered Cementitious Composites (ECC) are one HPFRCC that has shown remarkable promise for use in more sustainable infrastructure systems and buildings due to its unique tensile capabilities (see below) and micromechanics based design approach.

At the materials engineering stage, these research focuses on the development of new materials that judiciously incorporate industrial waste streams or utilize low impact processing techniques without jeopardizing the sustainable performance of the system over its entire life cycle.  Through application of SIMSS, this materials design is informed by life cycle assessment results to create materials that foster sustainable system performance rather a green material.

Courtesy of Kuraray Company

More information can be found in Lepech et al (2008).

Sustainable Structure Design & Construction Practices

Working with structural engineering researchers, this effort looks at the roles that structural engineers serve in meeting the overarching design goal of sustainable system performance.  Focusing on the appropriate selection of materials, engineering of structural systems, and construction of buildings that promote lower life cycle impacts through greater durability, improved hazard characterization and mitigation, building information models (BIMs), and reuse of structural components, the application of LCA techniques in performance-based design for sustainable built environments is an emerging field in structural engineering.

Such design theory has been demonstrated for more sustainable freeway bridge structures that utilize green ECC materials to replace failing expansion joints thereby reducing bridge maintenance events and reducing life cycle energy consumed in construction-related traffic congestion.
  More recently this work has been extended to the design of sustainable pavement overlays and other pavement structures.

Conceptualized ECC Joint

Constructed ECC Joint

More information can be found in Lepech et al (2005).

Sustainable Built Environment Systems

With over 90% of building life cycle impacts coming from the use phase, operating and maintaining buildings and infrastructure systems in ways that leverage new sustainable materials and structural designs is a strong research component of the SIMSS design approach.  This research focuses on the development of new life cycle modeling, optimization, and visualization techniques to enable sustainable operation and management of complex built environments and infrastructure systems.

This work focuses on the integration of efficient computational algorithms for system optimization, the use of sensor networks for dynamic management of sustainable building systems, and new data visualization tools for communicating complex sustainability impacts to a broad set of stakeholders involved with the building life cycle from design through end of life.

More information can be found in Zhang et al (2008).

Life Cycle Assessment

LCA is the analytic basis for performance-based sustainability design.  Without the ability to correctly measure the impacts of design and operation changes, design of a sustainable built environment remains impossible.  This research effort is integral to each activity of the research group.  This work includes the development of new life cycle data inventories, life cycle impact assessment techniques, and tools for constructing life cycle models. 

One facet of this research focuses on improved valuation of ecosystem services to enable more efficient accounting of environmental and social impacts in business decisions.

More information on these topics will be in publication soon.

Funding Agencies:

National Science Foundation

Michigan Department of Transportation

Stanford University Center for Integrated Facility Engineering

Dedicated Research Project Sites:

Sustainable Design and Manufacturing of Prefabricated Durable Infrastructure (Stanford CIFE 2009-2010 Seed Project)

Social Networking for Sustainable Building Practices (Stanford
CIFE 2009-2010 Seed Project)

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