Performance of Nonstructural Components in NPPs under High-Frequency Ground Motions

This study evaluates the seismic performance of nonstructural components subjected to strong high frequency ground motions (GMs), and further investigates the acceleration amplification factors considering involved uncertainties. For this purpose, a set of ground motion histories are modified to match the ground motion response spectrums for NPP sites in the western and eastern U.S. The seismic performance of nonstructural components is analyzed through time history analysis. Using this procedure, acceleration responses of floors and nonstructural components are evaluated, and the variation of amplification factors are estimated. For nonstructural components attached to structures with high natural frequency, the amplification factors can be large under GMs with high frequency contents compared to GMs with normal frequency contents. However, this may not lead to increased failure probabilities under GMs with high frequency contents

Seismic Reliability Analysis of NPP's Nonstructural Components using Surrogate Models

This study evaluates the accuracy and computational efficiency of seismic probabilistic risk assessment (SPRA) using a new surrogate model-based reliability analysis and compares the results with the conventional Monte Carle Simulation (MCS) method. The newly developed Kriging-based reliability analysis approach, called REAK, is in the class of Adaptive Kriging-based MCS (AK-MCS) methods, but with the ability to estimate error in failure probability estimates, which is used as the stopping criterion in the reliability analysis. It is shown that REAK can reliably capture the failure probability of nonstructural components located in buildings of nuclear power plants, however, with significantly smaller number of simulations compared to MCS. Results also indicate that the probability of acceleration of nonstructural components in the first floor exceeding that on the second floor is small but not zero, indicating that it cannot be neglected as commonly done in current risk analysis procedures

Functional links between clustered microRNAs: suppression of cell-cycle inhibitors by microRNA clusters in gastric cancer

microRNAs (miRNAs) play integral roles in diverse processes including tumorigenesis. miRNA gene loci are often found in close conjunction, and such clustered miRNA genes are transcribed from a common promoter to generate polycistronic primary transcript. The primary transcript (pri-miRNA) is then processed by two RNase III proteins to release the mature miRNAs. Although it has been speculated that the miRNAs in the same cluster may play related biological functions, this has not been experimentally addressed. Here we report that the miRNAs in two clusters (miR-106b∼93 ∼ 25 and miR-222 ∼ 221) suppress the Cip/Kip family members of Cdk inhibitors (p57Kip2, p21Cip1 and p27Kip1). We show that miR-25 targets p57 through the 3′-UTR. Furthermore, miR-106b and miR-93 control p21 while miR-222 and miR-221 regulate both p27 and p57. Ectopic expression of these miRNAs results in activation of Cdk2 and facilitation of G1/S phase transition. Consistent with these results, both clusters are abnormally upregulated in gastric cancer tissues compared to the corresponding normal tissues. Ectopic expression of miR-222 cluster enhanced tumor growth in the mouse xenograft model. Our study demonstrates the functional associations between clustered miRNAs and further implicates that effective cancer treatment may require a combinatorial approach to target multiple oncogenic miRNA clusters

Seismic performance evaluation of switchboard cabinets using nonlinear numerical models

Past earthquake events have shown that seismic damage to electrical power systems in commercial buildings, hospitals, and other systems such as public service facilities can cause serious economic losses as well as operational problems. A methodology for evaluation of the seismic vulnerability of electrical power systems is needed and all essential components of the system must be included. A key system component is the switchboard cabinet which houses many different elements which control and monitor electrical power usage and distribution within a building. Switchboard cabinets vary in size and complexity and are manufactured by a number of different suppliers; a typical cabinet design was chosen for detailed evaluation in this investigation. This study presents a comprehensive framework for the evaluation of the seismic performance of electrical switchboard cabinets. This framework begins with the introduction and description of the essential equipment in building electrical power systems and explains possible seismic damage to this equipment. The shortcomings of previous studies are highlighted and advanced finite element models are developed to aid in their vulnerability estimation. Unlike previous research in this area, this study proposes practical, computationally efficient, and versatile numerical models, which can capture the critical nonlinear behavior of switchboard cabinets subjected to seismic excitations. A major goal of the current study was the development of nonlinear numerical models that can accommodate various support boundary conditions ranging from fixed, elasto-plastic to free. Using both linear and nonlinear dynamic analyses, this study presents an enhanced evaluation of the seismic behavior of switchboard cabinets. First the dynamic characteristics of switchboard cabinets are determined and then their seismic performance is assessed through nonlinear time history analysis using an expanded suite of ground motions. The seismic responses and associated ground motions are described and analyzed using probabilistic seismic demand models (PSDMs). Based on the PSDMs, the effectiveness and practicality of common intensity measures are discussed for different components. Correlation of intensity measures and seismic responses are then estimated for each component, and their seismic performance and uncertainties are quantified in terms of engineering demand parameters. The results of this study are intended for use in the seismic vulnerability assessment of essential electrical equipment in order to achieve more reliable electrical power systems resulting in reduced overall risk of both physical and operational failures of this important class of nonstructural components.PhDCommittee Chair: Goodno, Barry J.; Committee Co-Chair: Craig, James I.; Committee Member: DesRoches, Reginald; Committee Member: Ellingwood, Bruce R.; Committee Member: Leon, Roberto T

Seismic intensity measures for probabilistic demand modeling of rocking rigid components

Nonstructural components such as electrical equipment have critical roles in the proper functionality of various infrastructure systems. Some of these devices in certain facilities should operate even under strong seismic shakings. However, it is challenging to define each mechanical and operational failure and determine system failure probabilities under seismic shakings due to the uncertainties in earthquake excitations and the diversity of electrical equipment, among other factors. Therefore, it is necessary to develop effective and practical probabilistic models for performance assessment of electrical equipment considering variations in equipment features and earthquakes. This study will enhance the understanding of the rocking behavior of nonstructural equipment and linear to nonlinear behavior of restrainers. In addition, the present study will generate probabilistic seismic demand models of rigid equipment for a set of conventional and novel intensity measures.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.Facult

Probabilistic capacity assessment of a prestressed concrete pile in a corrosive marine environment

This study aims to provide a comprehensive method for modeling and analyzing prestressed concrete substructure elements, specifically wharf piles, subjected to chloride-induced corrosion. Fully understanding this process is crucial to capturing uncertainties in structural response and providing accurate predictions of its time-dependent degradation mechanisms. A probabilistic modeling framework and detailed finite element model and analysis are employed to explore these effects. Results indicate a high degree of uncertainty captured by the spatial and time-dependent modeling techniques in addition to multiple significant modes of failure represented that were not previously considered in structures of this type.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.Facult

Seismic Assessment and Performance of Nonstructural Components Affected by Structural Modeling

Seismic probabilistic risk assessment (SPRA) requires a large number of simulations to evaluate the seismic vulnerability of structural and nonstructural components in nuclear power plants. The effect of structural modeling and analysis assumptions on dynamic analysis of 3D and simplified 2D stick models of auxiliary buildings and the attached nonstructural components is investigated. Dynamic characteristics and seismic performance of building models are also evaluated, as well as the computational accuracy of the models. The presented results provide a better understanding of the dynamic behavior and seismic performance of auxiliary buildings. The results also help to quantify the impact of uncertainties associated with modeling and analysis of simplified numerical models of structural and nonstructural components subjected to seismic shaking on the predicted seismic failure probabilities of these systems

A Bridge Condition Index for Transportation Asset Management in Ohio

SJN 135240A comprehensive and practical performance measure, called Ohio Bridge Condition Index (OBCI), has been developed in this project. OBCI is a cost-based index that ranges from zero to one and represents the performance of bridges at element-, component-, bridge-, and network-levels. The index effectively uses ODOT\u2019s bridge inventory and inspection databases. Effects of serviceability and safety features of bridges are objectively incorporated in this index through a broad set of direct and indirect consequences of various bridge conditions. Based on this novel index and implementing a mixed-integer linear programing technique, a systematic optimal budget allocation algorithm is developed that identifies the optimal Maintenance, Repair, and Replacement (MR&R) work plans for National Highway System (NHS) bridges of ODOT\u2019s districts for available budgets. Application of the proposed index to numerous Ohio bridges show that OBCI not only reflects the impacts of structural deficiencies, but also the adverse consequences imposed on users due to repair actions. It is also demonstrated that OBCI can effectively identify bridges with safety concerns and estimate bridge repair costs for various target performances. Furthermore, through the application of the optimization algorithm for the 484 NHS bridges in District 3, it is shown that the algorithm systematically assigns higher priority to work plans that reduce safety risks of bridges, and to bridges with high traffic demand and long detour length to enhance their serviceability