Holistic Design of Structures and Materials for Hazard Resilience and Energy Efficiency

        The building sector accounts for 41% of the primary annual energy consumption in the United States, where nearly 48% of the energy consumed in the residential sector is used for space conditioning and water heating. Traditionally, building energy systems and the structural back-frame are designed separately using independent, isolated criteria and approachesTo date, sustainability in civil structures is mainly achieved by material innovations and structural member reuse. Studies carried out by US Green Building Council (USGBC) indicated that improvements in individual building technology may achieve 30% improvement over conventional performance; to obtain a higher efficiency goal (50% improvement and beyond) independent measures will no longer suffice.  Leaps forward in sustainable, high performance building design require solutions that integrate the components and subsystems as a functional entirety to deliver efficiency throughout the building’s life cycle.
        The research at SHM&IM seeks pathways to integrate infrastructural material innovations and building energy subsystem design into traditional structural engineering by establishing the nexus among areas including structural optimization and form-finding, sustainable materials development, and building thermal design. We use an interactive approach where multiple performance objectives (i.e., structural, energetic, and life-cycle performance) are used for the (whole-building) system-level optimization.

[1] Shen Z, Brooks AL, and Zhou H., "Leveraging thermal storage in concrete structures for integrated Structural Resilience and Energy Efficiency", 2016 ACI Fall Convention, Philadelphia, PA, Oct. 23-26, 2016. Click here for the presentation.

Thermally Activated Building Systems and Assemblies
        Realizing the extraordinary ability of water to simultaneously convey thermal energy and transfer mechanical loads (through its internal pressure), the research being conducted at SHM&IM Lab investigates strategies to thermally activate building envelopes and enclosures using hydronic exchange.  Building materials and its architectural format (topology) are concurrently  studied for optimal  thermal (energetic) and mechanical (structural) performances.  The active cooling and heating strategy using hydronic circulation can be utilized in very large thermal mass (VLTM) buildings including R/C buildings, power plants etc., or be implemented into a variety of structures having high heating/cooling demands. 

Brooks A.L., Shen Z., and Zhou H., “Thermally activated building envelope for integrated hazard mitigation and thermal load management: an inspiration from homoeothermic animal skin.” 2016 ASCE Engineering Mechanics Institute (EMI)/ Probabilistic Mechanics & Reliability (PMC) Conference, Vanderbilt University, Nashville, TN, May 22-25. Click here for the presentation.

Shen Z., and Zhou H., “Coupled thermo-mechanical behavior of hydronically-activated concrete structures: consideration of material damage due to mechanical loading and temperature cycling.” 2016 ASCE Engineering Mechanics Institute (EMI)/ Probabilistic Mechanics & Reliability (PMC) Conference, Vanderbilt University, Nashville, TN, May 22-25. 

Innovative Construction Approaches Using Sustainable, Agro-waste Materials
        Agricultureal waste (agro-waste) based fibrous materials present a sustainable substitute to conventional construction materials including engineered wood and synthetic fiber reinforced plastic composites. The advantages of plant fiber-based materials include low cost, low density, good thermal insulation properties, and reduced dermal and respiratory irritation; in addition, the materials are renewable and may alleviate the shortage of wood resources in some countries where forestry sources are limited.  
        Research at SHM&IM Lab investigates an innovative “unibody” construction of structural components and assemblies using sustainable agro-waste plant-fiber materials. Unlike conventional light-frame constructions where plywood or light-gauge metal sheathings are installed onto the structural frame through fasteners, the construction process proposed herein forms a monolithic structure by utilizing the shapeable nature of plant fiber mats “casted-in-place” with the supporting frames. This not only will eliminate the structural integrity issue caused by problematic fastener behavior, it also creates an airtight building enclosure that effectively minimizes thermal and moisture breaching. 

Brooks A.L., and Zhou H., “Monolithic “Unibody” Light-frame Structures: An Integrated Solution for Multi-hazard Mitigation and Building Energy Enhancement.” 2016 ASCE Geo-Structural Congress, Phoenix, AZ, April 11 – 15, 2016Click here for the presentation, and full paper.
Energy Storing, Self-sensing Structural Materials      
The high-strength structural carbon fibers are not only strong but also electrical conductive by nature. By utilizing carbon fiber (and its woven fabrics) as a strong and electrically conductive backbone, a new paradigm of functional composite design is opened where self-sensing and/or energy-storing functionalities can be integrated into the structural load-paths of various aerospace, automotive, and unmanned vehicular (UMV) structures
Shen, Z., and Zhou, H. (2017), Mechanical and electrical behavior of carbon fiber structural capacitors: effects of delamination and interlaminar damage. Composite Structures (166): 38-48Click here for the paper.

Shen, Z. and Zhou, H. (2016), Carbon fiber-based structural electric capacitors: coupled-mechanical-electrical behavior and effect of interlaminar damage. Proc. 2016 ASCE Earth and Space Conference, Orlando, FL, April 11 – 15, 2016: 787-796. Click here for the paper.

Behavior and Stability of Structures during Construction
(Photo: Construction of the Montgomery Outer Loop Bridge, Photo Courtesy of Sam Poynter Jr., Dowson Bridge Inc.)

        Current design code and specifications focus mostly on constructed structure systems where all 
members and subsystems are connected and cured to form a load-sustaining unit. However, due to different load and support conditions, structures can behave very differently during early stages of construction. Using interactive finite element modeling updated by real-time field test data, we study the behavior of structures and structural members throughout the entire course of construction (e.g., stability of prefabricated members during transport and erection, lock-in force history, and member misalignment etc.). For example, we are currently investigating how geometrical features of a horizontally curved bridge girder would affect its stability during girder transportation, erection and deck placement. We employ an interactive finite element method, coupled with real-time status monitoring, to benchmark the impacts of the member geometry (e.g., section slenderness, curvature) and external excitations (vibrations during transport, lateral wind etc.).

(Installation of wireless field testing and monitoring systems on the girder pieces of the Pea River Bridge, Elba, AL.)

Funding Source: FHWA/ALDOT