Advances in Structural Engineering Research

Single Abstract

343082 - Probabilistic Analysis of Failure Modes of Lattice Transmission Towers under Extreme Wind Hazards

Friday, April 20
11:00 AM - 12:30 PM
Location: 202A

Electric transmission lines face substantial risk of damage in hurricane prone regions around the world. Past failures of these systems resulted in considerable economic loss and societal disruptions; these events highlight the critical role of transmission systems in supporting power delivery to large geographic areas. Investigations of past wind-induced failures of transmission towers revealed multiple modes of failure for these structures. In addition to differences in configurations and other design features as well as wind exposures, uncertainties in dimensions of elements, their material properties, and wind-induced pressures may considerably affect dominant modes of failure and their likelihood of occurrence. Deterministic approaches commonly used for the analysis and design of transmission towers are not adequate to identify various modes of failure of tower structures as these methods neglect the element of uncertainty; stochastic approaches, on the other hand, can address this limitation.
This study generates strategic random realizations of demands and capacities of elements of a common double-circuit steel lattice transmission tower considering uncertainties in material properties and dimensions of tower elements, rigidity of connections, and wind induced loads on the tower. Subsequently, the tower model is analyzed for each realization of demands and capacities to identify possible failure modes. Nonlinear static pushover analysis in OpenSEES platform is used for this purpose. The generated Finite Element models in OpenSEES consider material nonlinearities as well as buckling and P-Delta effects in tower elements and geometric nonlinearities in conductors. This modeling procedure is validated using an existing pulling test of a full-scale steel lattice transmission tower to ensure that the realistic behavior of tower elements and connections are captured properly. Response surface method is adopted here to statistically analyze results of randomly generated FE models of towers, and to identify the impact of each random variable on the occurrence of each mode of failure and the overall performance of the tower. Results indicate that a configuration of lattice transmission tower may have several significant modes of failure, and the occurrence of each failure mode depends on several geometric and material properties of the tower. The design procedure of the towers should consequently account for uncertainties in significant random variables.
The presented numerical modeling procedure and uncertainty analysis benefit structural engineers with appropriate ways for analysis and design of transmission towers under strong wind loads. The identified modes of failure of these structures and the characterized impacts of various uncertain material and geometric variables on the occurrence of each mode will provide structural engineers and researchers with a deeper understanding of the performance of towers under extreme events and the role of uncertainties in the failure of these structures. This can facilitate development of practical and cost effective solutions to avoid undesirable modes of failure in towers and reduce their overall likelihood of failure under extreme wind hazards in the future.

Kyunghwa Cha

Graduate Research Fellow
Ohio State University

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Yousef Mohammadi Darestani

Graduate Research Assistant
The Ohio State University

Yousef is a PhD candidate in Structural Engineering at the Ohio State University. He joined RAMSIS lab in August 2014 as a Graduate Research Associate. Prior to that, he got his B.Sc. in Civil Engineering from the University of Tehran, Tehran, Iran, in 2011 and his M.Sc. in Structural Engineering from Sharif University of Technology, Tehran, Iran, in 2014. His research focuses on reliability and resilience assessment and enhancement of power distribution lines against hurricanes. His research is supported by National Science Foundation. The goal of his research is to improve the current knowledge on the behavior of distribution lines by developing stochastic Finite Element models for distribution lines integrated with time-dependent decay models to simulate the current and future state of the response of distribution poles to various climate conditions. Moreover, his research will develop novel multi-dimensional fragility functions for utility lines and merged them with hurricane hazard models, distribution network's response and restoration models to devise methods to improve the resilience of power networks.

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Arindam Chowdhury

Associate Professor and Director, Laboratory for Wind Engineering Research
Florida International University

Associate Professor
Director, Laboratory for Wind Engineering Research,
International Hurricane Research Center
Ph.D., Iowa State University, 2004
Structural and Wind Engineering

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Peter Irwin

Professor of Practice
Florida International University

n/a

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Abdollah Shafieezadeh

Assistant Professor
The Ohio State University

Critical infrastructure systems (CIs) are becoming increasingly vulnerable to system-wide failure primarily due to aging, natural and manmade hazards, climate change, and increased interdependencies, among other factors. Quantitative and qualitative assessment of the associated risk is crucial in pre-event planning and post-event response. Risk assessment and management of structural and infrastructure systems (RAMSIS) lab develops and applies probabilistic risk analysis frameworks to various CIs and their components to assess their reliability and resilience against perturbations. This can provide valuable knowledge about a number of principal effects such as traffic disruption, impact on the regional and global economy, and resilience of systems and communities. The focus of Dr. Shafieezadeh's research is on numerical modeling and fragility assessment of complex systems, such as seaports, bridges, and physical assets of power grids with consideration of soil-foundation-structure interactions and liquefaction effects, probabilistic modeling of deterioration processes of reinforced and prestressed concrete structures coupled with FE simulations, optimal maintenance policies for large aging infrastructure assets using stochastic methods, advanced protection of critical geo-structural systems against extreme hazards such as earthquakes and strong winds using passive, active, and semi-active control strategies based on stochastic methods, reliability and resilience assessment of geo-structural systems and critical infrastructures against natural and manmade hazards.

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