NEESR-SG Innovative Applications of Damage Tolerant Fiber-Reinforced Cementitious Materials for New Earthquake-Resistant Structural Systems and Retrofit of Existing Structures

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Abstract for: NEESR-SG Innovative Applications of Damage Tolerant Fiber-Reinforced Cementitious Materials for New Earthquake-Resistant Structural Systems and Retrofit of Existing Structures, CMS proposal 0530383 PI: James K. Wight, University of Michigan Ann Arbor It is proposed to use NEES testing facilities and associated simulation capabilities to develop new coupled wall systems and retrofit schemes for framed construction through the use of high-performance fiber reinforced cement composites (HPFRCC). This research was conceived from the idea that the next generation of reinforced concrete (RC) structures should utilize ductile cementitious materials in critical regions, rather than extensive reinforcement detailing to provide shear resistance and concrete confinement. A high-performance fiber reinforced cementitious composite (HPFRCC) that is ductile in tension, does not spall in compression, behaves like a confined concrete, and is capable of providing confinement to normal reinforcement, will be used. In addition to enhancing confinement and flexural behavior in plastic hinging regions, HPFRCC materials are capable of providing ductility and energy dissipation capabilities to shear critical members that are normally a difficult design issue for RC structures. The use of HPFRCC materials for such members will lead to less complicated reinforcement details, will be easier to construct, and will provide a high degree of damage tolerance, leading to superior seismic performance and reduced post-earthquake repair costs. The research will be conducted by a diverse and multidisciplinary team from three major universities, Michigan, Stanford and Illinois, with expertise in structural engineering, computational simulation, materials engineering, information technology and cyberinfrastructure deployment. Cooperative assistance with computation and simulation requirements has been offered by the MGRID and Sakai research groups at the University of Michigan. Intellectual Merit: HPFRCC materials will be used as a tool to develop new coupling beam designs for RC structural wall systems and infill panels for seismic retrofitting of existing steel or RC framed structures. Shear wall systems are very popular for medium-rise structures in zones of high seismicity and the development of a coupling beam that is easier to construct than current diagonal reinforcing schemes, yet still can sustain large shear stress and displacement demands with good stiffness retention, will be a major original contribution. Also, there is a significant need for an efficient method to upgrade existing critical facilities that require structural and/or non-structural system protection. The development of ductile precast HPFRCC infill panels will result in an effective and practical method for enhancing the strength, stiffness and energy dissipation capabilities of deficient steel and RC frame structures, while allowing them to remain in full service during rehabilitation activities. Structural and materials engineering experts will collaborate on developing HPFRCC mixture designs that can be handled in a normal batch plant, trucked to the site and pumped to the casting location. Analytical models that accurately reproduce the behavior of HPFRCC under various stress states will be developed for simulation of structural behavior, for the control of the proposed pseudo-dynamic experiments, as well as for use by the earthquake engineering community in general. The combination of the computing power of the NEESgrid and MGRID, integrated with various structural simulation packages, offers a unique opportunity that will be pursued for the incorporation of highly detailed models in pseudo-dynamic testing of wall and frame systems. Broader impacts: 1) One of the most significant broader impacts of this research will be the wider acceptance and use of highly damage-tolerant fiber reinforced concretes for enhancing structural performance during earthquakes. 2) The results of this research will provide the NEES community with the capability of using more sophisticated simulation models for hybrid testing of structural systems. 3) A multi-use environment based on the Sakai software platform (used in NEESgrid and course management systems across the country) will be further developed, where students and researchers will be able to do coursework and participate in experiments without negotiating separate tools, authenticating to different systems, or learning new interfaces. 4) A participatory experience for pre-engineering students at institutions affiliated with the Midwest Instructional Technology Center (MITC) will be created. Through the involvement of a diverse set of graduate and undergraduate researchers and outreach to students at small colleges, particularly women and under-represented minority students, a new generation of students will be introduced to the use of high-performance structural materials, behavior of structures during earthquakes, and sophisticated structural analysis and simulation techniques.