This research develops and validates computational tools for the design and analysis of structural components and systems constructed with Ultra-High Performance Concrete (UHPC). The modeling strategy utilizes the Lattice Discrete Particle Model (LDPM) to represent UHPC material and structural member response, and extends a structural-level triaxial continuum constitutive law to account for the addition of discrete fibers. The approach is robust, general, and could be utilized by other researchers to expand the computational capability and simulate the behavior of different composite materials. The work described herein identifies the model material parameters by conducting a complete material characterization for UHPC, with and without fiber reinforcement, describing its behavior in unconfined compression, uniaxial tension, and fracture toughness. It characterizes the effect of fiber orientations, fiber-matrix interaction, and resolves the issue of multi-axial stress states on fiber pullout. The capabilities of the computational models are demonstrated by comparing the material test data that were not used in the parameter identification phase to numerical simulations to validate the models' predictive capabilities. These models offer a mechanics-based shortcut to UHPC analysis that can strategically support ongoing development of material and structural design codes and standards. / Ph. D. / This research develops and validates new computer-based methods to analyze and design civil infrastructure constructed with ultra-high performance concrete (UHPC), achieved when steel fibers are combined with a finely graded cement matrix. With superior performance characteristics in comparison to regular concrete, UHPC is studied herein for its strong potential to advance the durability, efficiency, and resiliency of new and existing infrastructure. The simulation-based methods are extensively verified with novel experiments that evaluate the material limits and failure modes when compressed, bent, or stretched, considering fiber volume and orientation. The computer-based tools can be used to realistically assess the structural performance of innovative UHPC applications in buildings, bridges, and tunnels under natural hazards, leading to surpassed levels of structural efficiency and resiliency across civil infrastructure.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/73381 |
| Date | 04 November 2016 |
| Creators | El Helou, Rafic Gerges |
| Contributors | Civil and Environmental Engineering, Moen, Cristopher D., Cusatis, Gianluca, Grasley, Zachary, Koutromanos, Ioannis, Roberts-Wollmann, Carin L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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