New MCEER Publications: Spring 2016

Published May 19, 2016

Three new technical reports are available. All publications are now available free of charge and can be downloaded from the online MCEER Publications Catalog.

Seismic Isolation of Nuclear Power Plants using Sliding Bearings

Manish Kumar, Andrew S. Whittaker and Michael C. Constantinou

MCEER-15-0006 | 12/27/2015 | 620 pages

Seismic Performance Evaluation of Precast Girders with Field-Cast Ultra High Performance Concrete (UHPC) Connections

TOC: The table of contents is provided.

Keywords: Sliding isolation bearings, nuclear power plants, temperature dependence of friction, seismic hazard definitions, seismic risk calculations

Abstract: This report presents a study on the seismic isolation of nuclear power plants (NPPs), with a focus on single concave sliding bearings. The key goals of the study were to 1) characterize the coefficient of friction at the sliding surface, 2) determine the influence of the definition of the coefficient of friction and alternate representations of seismic hazard on the response of isolated NPPs, and 3) quantify the seismic vulnerability of isolated NPPs. Consideration of heating effects may substantially influence the response of an isolated NPP. The uniform hazard response spectrum should be used to define seismic hazard for analysis of isolated NPPs with explicit consideration of the difference in amplitude of the orthogonal horizontal components of ground shaking. A hard stop must be provided to ensure that failure of the isolation system is not a key contributor to the seismic core damage frequency. Seismic risk can be reduced by designing and testing isolators for displacements greater than those expected in beyond design basis shaking.

Quintuple Friction Pendulum Isolator Behavior, Modeling and Validation

Donghun Lee and Michael C. Constantinou

MCEER-15-0007 | 12/28/2015 | 114 pages

Seismic Performance Evaluation of Precast Girders with Field-Cast Ultra High Performance Concrete (UHPC) Connections

TOC: The table of contents is provided.

Keywords: Quintuple Friction Pendulum Isolator, Spherical Sliding Isolator, Multi-stage Adaptive Behavior, Analytical Model, Computational Model

Abstract: This report describes the Quintuple Friction Pendulum isolator, which is a spherical sliding isolator with six sliding surfaces. Analytical models of behavior are presented to describe the force-displacement loop for two general cases of geometric and frictional parameters. The analytical model is useful in performing simplified calculations and in verifying more complex computational models. Computational models are also presented which may be implemented in commercial software. A model isolator was tested and the results are used to validate the analytical and computational models.

Seismic Isolation of Nuclear Power Plants using Elastomeric Bearings

Seismic Isolation of Nuclear Power Plants using Elastomeric Bearings

MCEER-15-0008 | 12/29/2015 | 515 pages

Seismic Performance Evaluation of Precast Girders with Field-Cast Ultra High Performance Concrete (UHPC) Connections

TOC: The table of contents is provided.

Keywords: Elastomeric isolation bearings, nuclear structures, heating, cavitation, tension, extreme loading, verification and validation

Abstract: This report addresses US Nuclear Regulatory Commission-mandated issues for seismic isolation of nuclear power plants (NPPs). Advanced numerical models of low-damping rubber (LDR) and lead-rubber (LR) elastomeric bearings are developed to permit analysis of base-isolated NPPs subjected to extreme earthquake loadings. The models are verified and validated following ASME best practice, and implemented in OpenSees and ABAQUS to enable use by researchers and the design professional community. Experiments are conducted to characterize behavior of elastomeric bearing under tensile and shear loadings. Numerical issues in computing response of base-isolated NPPs are addressed. Two representations of a NPP isolated with LR bearings, a two-node macro model and a lumped-mass stick model, are subjected to design and beyond design basis earthquake shaking. Simplified and advanced representations of LR bearing behavior are considered. The results allow a reader to judge which representation of an isolated NPP (macro model or lumped-mass stick) and which features, if any, of the advanced isolator model are needed to compute response for different intensities of earthquake shaking.