Title: Performance-based design optimization of steel structures subjected to seismic actions
Finding an optimal design for a structural system subject to seismic actions to minimize failure probability, repair costs, and injuries to occupants, significantly contributes to the resilience of buildings in earthquake regions. This research presents a comprehensive framework for the performance-based design optimization of steel structures, incorporating the Performance-Based Earthquake Engineering (PBEE) methodology delineated in FEMA P-58 [1]. A selected set of ground motions, consistent with the seismic hazard intensity of interest, and a nonlinear finite element model, established using OpenSees, enable the assessment of the system's dynamic response. To address the computational complexity related to evaluating the probability of failure of the system during an optimization iteration when using the PBEE methodology for assessing performance, this study introduces metamodeling techniques as a substitute for the original high-fidelity nonlinear finite element model. In particular, Kriging is employed to approximate both the median and standard deviation of the Engineering Demand Parameters (EDPs) in the design domain. The parameters of the Kriging metamodels are derived from nonlinear dynamic analyses performed using the original high-fidelity model and an optimal sampling plan obtained through Latin Hypercube sampling. Under the assumption of a lognormal distribution, the metamodel is then used to generate a large number of simulated demand sets necessary for the Monte Carlo procedure adopted by FEMA P-58 to calculate the distribution of probable losses for any given value of the design variable vector. Additionally, the median and standard deviation of the fragility function modeling collapse are also approximated by a Kriging metamodel, in which the parameters are derived from an Incremental Dynamic Analysis (IDA) for any given value of the design variable vector. The scheme is illustrated in a full-scale case study consisting of the performance-based optimization of the buckling-restrained braces of a steel seismic force-resisting system in terms of expected losses and construction costs. The study demonstrates that the proposed risk-based optimization scheme effectively balances construction costs with expected financial losses from earthquakes, thus enhancing the seismic performance of the system.[1] Applied Technology Council, & National Earthquake Hazards Reduction Program (US). (2012). Seismic performance assessment of buildings. Federal Emergency Management Agency. more »« less
Nagawkar, Jethro; Leifsson, Leifur
(, Proceedings of the ASME 2020 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2020)
null
(Ed.)
Abstract This paper demonstrates the use of the polynomial chaos-based Cokriging (PC-Cokriging) on various simulation-based problems, namely an analytical borehole function, an ultrasonic testing (UT) case and a robust design optimization of an airfoil case. This metamodel is compared to Kriging, polynomial chaos expansion (PCE), polynomial chaos-based Kriging (PC-Kriging) and Cokriging. The PC-Cokriging model is a multi-variate variant of PC-Kriging and its construction is similar to Cokriging. For the borehole function, the PC-Cokriging requires only three high-fidelity samples to accurately capture the global accuracy of the function. For the UT case, it requires 20 points. Sensitivity analysis is performed for the UT case showing that the F-number has negligible effect on the output response. For the robust design case, a 75 and 31 drag count reduction is reported on the mean and standard deviation of the drag coefficient, respectively, when compared to the baseline shape.
Pei, S.; Dolan, J.; Zimmerman, R.; McDonnell, E.; Line, p.; Popovski, P.
(, Proceedings of the International Network for Timber Engineering Research (INTER))
Blass, Hans
(Ed.)
Wood buildings in North American has been predominantly constructed using light-framed wood systems since early 1900’s, with only limited exception of heavy timber construction in some non-residential applications. This situation is likely to change in the future with the growing acceptance of mass timber construction in the region. In fact, a number of mass timber buildings have been constructed in recent years in the U.S. and Canada, including low- to mid-rise mixed-use buildings (e.g. UMass Student Center, T3 building) and tall towers (e.g. Brocks Commons at UBC). Most of these buildings utilized cross laminated timber (CLT) or nail laminated timber (NLT) floors and heavy timber framing systems to support gravity loads, and a non-wood lateral system such as concrete shear walls or a braced steel frame to resist wind and seismic loads. Although CLT material and glulam products have been recognized in the U.S. and Canada (IBC (2018) and NBCC (2015), there is currently no mass timber lateral systems in the U.S. and only one system (platform style panelized CLT shear wall) in Canada that is currently recognized by the building codes. As a result, special design procedures and review/approval processes must be followed for any building intended to use a mass timber lateral system. There is a need to promote codification of mass timber lateral systems in order to help further develop mass timber building market in North American. At the time of this paper, there has been an on-going effort to devel-op seismic design parameters for panelized CLT shear walls in the U.S. (ref) following the FEMA P695 procedure for platform construction. The other lateral system that at-tracted significant attention and research resources is post-tensioned CLT rocking wall system, which has the potential to be applicable to balloon framed low-rise to tall wood buildings. This paper will focus on recent research development on CLT rocking wall system in the U.S. and the effort to develop a seismic design procedure for this system for inclusion in the NDS Special Design Provisions for Wind and Seismic (SPDWS)(2008). While the expensive and time consuming process of the FEMA P695 process would provide the ability to use the equivalent lateral force method for design purposes, this path is not part of the discussion included here.
This project will develop a new structural system that will protect buildings, their contents, and occupants during large earthquakes and will enable immediate post-earthquake occupancy. This earthquake-resilient structural system will be particularly valuable for essential facilities, such as hospitals, where damage to buildings and contents and occupant injuries must be prevented and where continuous occupancy performance is imperative. The new system will use practical structural components to economically protect a building from damaging displacements and accelerations. The project team will collaborate with Japanese researchers to study the new system with full-scale earthquake simulations using the 3D Full-Scale Earthquake Testing Facility (E-Defense) located in Miki, Japan, and operated by the National Research Institute for Earth Science and Disaster Resilience. This project will advance national health, prosperity, and welfare by preventing injuries and loss of human life and minimizing social and economic disruption of buildings due to large earthquakes. An online course on resilient seismic design will be developed and offered through the American Institute of Steel Construction night school program, which will be of interest to practicing engineers, researchers, and students across the country. This project contributes to NSF's role in the National Earthquake Hazards Reduction Program. The novel steel frame-spine lateral force-resisting system with force-limiting connections (FLC) that will be developed in this project will control multi-modal seismic response to protect a building and provide resilient structural and non-structural building performance. This frame-spine-FLC system will rely on a conventional, economical base system that resists a significant proportion of the lateral load. The system judiciously employs floor-level force-limiting deformable connections and an elastic spine to protect the base system. Integrated experiments and numerical simulations will provide comprehensive understanding of the new frame-spine-FLC system, including rich full-scale experimental data on building seismic performance with combined in-plane, out-of-plane, and torsional response under 3D excitation. The FLCs will be tested using the NHERI facility at Lehigh University. This project will be conducted in collaboration with an ongoing synergistic research program in Japan. The extensive dataset from this integrated U.S.-Japan research program will enable unique comparisons of structural and non-structural performance, including critical acceleration-sensitive hospital contents that directly affect the health and safety of patients. In addition, the dataset will enable the advancement of computational modeling for the assessment of building performance and the development of practical, accurate models for use in design that capture the complex 3D structural response that occurs during an earthquake.
This project will develop a new structural system that will protect buildings, their contents, and occupants during large earthquakes and will enable immediate post-earthquake occupancy. This earthquake-resilient structural system will be particularly valuable for essential facilities, such as hospitals, where damage to buildings and contents and occupant injuries must be prevented and where continuous occupancy performance is imperative. The new system will use practical structural components to economically protect a building from damaging displacements and accelerations. The project team will collaborate with Japanese researchers to study the new system with full-scale earthquake simulations using the 3D Full-Scale Earthquake Testing Facility (E-Defense) located in Miki, Japan, and operated by the National Research Institute for Earth Science and Disaster Resilience. This project will advance national health, prosperity, and welfare by preventing injuries and loss of human life and minimizing social and economic disruption of buildings due to large earthquakes. An online course on resilient seismic design will be developed and offered through the American Institute of Steel Construction night school program, which will be of interest to practicing engineers, researchers, and students across the country. This project contributes to NSF's role in the National Earthquake Hazards Reduction Program. The novel steel frame-spine lateral force-resisting system with force-limiting connections (FLC) that will be developed in this project will control multi-modal seismic response to protect a building and provide resilient structural and non-structural building performance. This frame-spine-FLC system will rely on a conventional, economical base system that resists a significant proportion of the lateral load. The system judiciously employs floor-level force-limiting deformable connections and an elastic spine to protect the base system. Integrated experiments and numerical simulations will provide comprehensive understanding of the new frame-spine-FLC system, including rich full-scale experimental data on building seismic performance with combined in-plane, out-of-plane, and torsional response under 3D excitation. The FLCs will be tested using the NHERI facility at Lehigh University. This project will be conducted in collaboration with an ongoing synergistic research program in Japan. The extensive dataset from this integrated U.S.-Japan research program will enable unique comparisons of structural and non-structural performance, including critical acceleration-sensitive hospital contents that directly affect the health and safety of patients. In addition, the dataset will enable the advancement of computational modeling for the assessment of building performance and the development of practical, accurate models for use in design that capture the complex 3D structural response that occurs during an earthquake.
The dynamic stall phenomenon produces adverse aerodynamic loading, which negatively affects the structural strength and life of aerodynamic systems. Aerodynamic shape optimization (ASO) provides a practical approach for delaying and mitigating dynamic stall characteristics without the addition of an auxiliary system. A typical ASO investigation requires multiple evaluations of accurate but time-consuming computational fluid dynamics (CFD) simulations. In the case of dynamic stall, unsteady CFD simulations are required for airfoil shape evaluation; combining it with high-dimensions of airfoil shape parameterization renders the ASO investigation computationally costly. In this study, metamodel-based optimization (MBO) is proposed using the multifidelity modeling (MFM) technique to efficiently conduct ASO investigation for computationally expensive dynamic stall cases. MFM methods combine data from accurate high-fidelity (HF) simulations and fast low-fidelity (LF) simulations to provide accurate and fast predictions. In particular, Cokriging regression is used for approximating the objective and constraint functions. The airfoil shape is parameterized using six PARSEC parameters. The objective and constraint functions are evaluated for a sinusoidally oscillating airfoil with the unsteady Reynolds-averaged Navier-Stokes equations at a Reynolds number of 135,000, Mach number of 0.1, and reduced frequency of 0.05. The initial metamodel is generated using 220 LF and 20 HF samples. The metamodel is then sequentially refined using the expected improvement infill criteria and validated with the normalized root mean square error. The refined metamodel is utilized for finding the optimal design. The optimal airfoil shape shows higher thickness, larger leading-edge radius, and an aft camber compared to baseline (NACA 0012). The optimal shape delays the dynamic stall occurrence by 3 degrees and reduces the peak aerodynamic coefficients. The performance of the MFM method is also compared with the single-fidelity metamodeling method using HF samples. Both the approaches produced similar optimal shapes; however, the optimal shape from MFM achieved a minimum objective function value while more closely satisfying the constraint at a computational cost saving of around 41%.
Rodrigues, Isabela D, Spence, Seymour M, and Beck, André T. Performance-based design optimization of steel structures subjected to seismic actions. Retrieved from https://par.nsf.gov/biblio/10634309. Ibero-Latin American Congress on Computational Methods in Engineering (CILAMCE) . Web. doi:10.55592/cilamce.v6i06.10425.
Rodrigues, Isabela D, Spence, Seymour M, & Beck, André T. Performance-based design optimization of steel structures subjected to seismic actions. Ibero-Latin American Congress on Computational Methods in Engineering (CILAMCE), (). Retrieved from https://par.nsf.gov/biblio/10634309. https://doi.org/10.55592/cilamce.v6i06.10425
Rodrigues, Isabela D, Spence, Seymour M, and Beck, André T.
"Performance-based design optimization of steel structures subjected to seismic actions". Ibero-Latin American Congress on Computational Methods in Engineering (CILAMCE) (). Country unknown/Code not available: XLVCILAMCE. https://doi.org/10.55592/cilamce.v6i06.10425.https://par.nsf.gov/biblio/10634309.
@article{osti_10634309,
place = {Country unknown/Code not available},
title = {Performance-based design optimization of steel structures subjected to seismic actions},
url = {https://par.nsf.gov/biblio/10634309},
DOI = {10.55592/cilamce.v6i06.10425},
abstractNote = {Finding an optimal design for a structural system subject to seismic actions to minimize failure probability, repair costs, and injuries to occupants, significantly contributes to the resilience of buildings in earthquake regions. This research presents a comprehensive framework for the performance-based design optimization of steel structures, incorporating the Performance-Based Earthquake Engineering (PBEE) methodology delineated in FEMA P-58 [1]. A selected set of ground motions, consistent with the seismic hazard intensity of interest, and a nonlinear finite element model, established using OpenSees, enable the assessment of the system's dynamic response. To address the computational complexity related to evaluating the probability of failure of the system during an optimization iteration when using the PBEE methodology for assessing performance, this study introduces metamodeling techniques as a substitute for the original high-fidelity nonlinear finite element model. In particular, Kriging is employed to approximate both the median and standard deviation of the Engineering Demand Parameters (EDPs) in the design domain. The parameters of the Kriging metamodels are derived from nonlinear dynamic analyses performed using the original high-fidelity model and an optimal sampling plan obtained through Latin Hypercube sampling. Under the assumption of a lognormal distribution, the metamodel is then used to generate a large number of simulated demand sets necessary for the Monte Carlo procedure adopted by FEMA P-58 to calculate the distribution of probable losses for any given value of the design variable vector. Additionally, the median and standard deviation of the fragility function modeling collapse are also approximated by a Kriging metamodel, in which the parameters are derived from an Incremental Dynamic Analysis (IDA) for any given value of the design variable vector. The scheme is illustrated in a full-scale case study consisting of the performance-based optimization of the buckling-restrained braces of a steel seismic force-resisting system in terms of expected losses and construction costs. The study demonstrates that the proposed risk-based optimization scheme effectively balances construction costs with expected financial losses from earthquakes, thus enhancing the seismic performance of the system.[1] Applied Technology Council, & National Earthquake Hazards Reduction Program (US). (2012). Seismic performance assessment of buildings. Federal Emergency Management Agency.},
journal = {Ibero-Latin American Congress on Computational Methods in Engineering (CILAMCE)},
publisher = {XLVCILAMCE},
author = {Rodrigues, Isabela D and Spence, Seymour M and Beck, André T},
}
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