Development, Verification, and Validation of a Hybrid Testing Framework for Latticed Structures with Nonlinear Geometric Effects
1 online resource (150 pages) : PDF
University of North Carolina at Charlotte
Hybrid simulation is an increasingly popular experimental method for structural dynamics research, as it offers the realism and exploratory power of full-scale testing at a fraction of the cost and size by resolving a structural system into complementary experimental and analytical substructures to be analyzed simultaneously as part of a single simulation. In order to promote the expansion of hybrid simulation into new areas of applied structural dynamics research within the energy industry, a pseudodynamic hybrid simulation software framework was developed, numerically verified, and experimentally validated. This framework employs a combination of an iterative implicit integration scheme and an α-operator splitting scheme to perform dynamic analysis of highly nonlinear latticed structures. Historically, iterative methods have been avoided in hybrid simulation, since physical iterations may produce unintended and irrecoverable plastic deformation of the test specimen within the iteration, thereby corrupting the fidelity of the hybrid simulation. The software framework implemented in this thesis enforces iterative displacements numerically rather than physically, thus avoiding experimental errors associated with the path dependency of the experimental substructure. In this work, the framework was numerically verified using a model of a simple planar truss subjected to harmonic loading and a model of a large space truss subjected to base excitation from an earthquake accelerogram. Analyses accounting for geometric and material nonlinearities both separately and in combination with one another were verified by comparison of predicted displacement time histories to results generated through an application programming interface with a commercial finite element software. Considerations involved in effective verification of the software, including the effect of the time step size on the accuracy of the framework, are discussed. Following verification, the hybrid testing software framework was experimentally validated through simulations of a power transmission tower loaded dynamically by theoretical galloping of an ice-covered conductor and a ground wire. A hybrid simulation was first performed within the linear elastic range of the specimen material. Excitation amplitudes were then increased into a range producing nonlinear plastic behavior of the experimental substructure. The observed displacement time histories and response hysteresis exhibited strong correlation with results from numerical simulations, ultimately validating the implementation of the framework. Lastly, recommendations are made for future developments and expansions of the software.
EXPERIMENTAL STRUCTURAL DYNAMICSHYBRID SIMULATIONSIMULATION SOFTWARESTRUCTURAL TESTINGTRANSMISSION TOWER TESTING
Weggel, DavidTempest, Brett
Thesis (M.S.)--University of North Carolina at Charlotte, 2015.
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