Pipeline Geohazards Screening: Using Results of Flood Scour Assessments to Provide a Simple Screening Tool for Pipeline Watercourse Crossings for Western Canada

Pipeline watercourse crossing assessments typically require field investigations, river surveys, and detailed scour analyses to predict whether or not a pipeline may be subject to flood scour deeper than their depth of cover (DOC). Flood scour algorithms rely on discharge, median grain size, and some measure of channel cross-sectional area to determine the tractive force of water on the stream bed. These algorithms are applied to non-cohesive sediments typical of fluvial systems. To better define pipeline threats at a screening level, reducing unnecessary field and analytical expenses, and focusing effort on credible hazards, we developed a flood scour screening tool that uses return period discharge (Q) as the only input requirement. In order to develop the tool, we plotted the results of over 400 detailed scour assessments for several grain sizes (1100 data points) completed in Alberta and British Columbia, in 2017, 2018 and 2019. The results clearly show the importance of channel variability and grain size, but also show definable discharge related trends. We compared the results of the National Engineering Handbook (NEH) and the United States Bureau of Reclamation (USBR) methods, both of which use industry accepted algorithms. We developed, and provided herein, relationships that can be used to screen out scour assessments at watercourse crossings where DOC is already known, or to support and expedite field programs where DOC is being obtained. If only Q is known, then a single graph, or single equation is used for a given region using fine sand as the assumed median grain size. If both Q and median grain size are known, then the user can determine a slightly less conservative result from a series of complementary equations. In all cases, we propose using the mean result of the USBR method, originally intended for design, to fully capture the potential variability in the calculated NEH flood scour. While conservative, the tool is easy to use, and we expect it will substantially reduce the assessment effort on smaller, or less erosive streams.

Robust H∞ filtering for Markovian jumping static neural networks with time-varying delays

The problem of robust H∞ filtering for Markovian jumping static neural networks with time-varying delays is considered in this paper. The effect of the activation function on the time delays is comprehensively considered. Based on Wirtinger inequality, a new inequality is quoted to solve the Lyapunov functions with the double-integral terms. Then, a less conservative result on the robust H∞ filtering is obtained, which guarantees the resulting error systems stochastically stable and satisfies a prescribed H∞ performance index. The effectiveness of the developed results is finally demonstrated by numerical examples.

Applicability of Seismic Fatigue Evaluation by JSME Code Case, NC-CC-008

A Code Case, JSME S NC1, NC-CC-008, in the framework of JSME Nuclear Codes and Standards has been published. New seismic evaluation methodology for piping by utilizing advanced elastic-plastic response analysis method and strain-based fatigue criteria has been incorporated into the code case. It can achieve more rational seismic design than the current rule. This paper demonstrates validity and applicability of fatigue evaluation method proposed in the code case. Experimental results of a shaking table test for a piping model is used for comparing the evaluation by the current rule with one by the code case. As a result, it is confirmed that the code case can provide a rational and conservative result in the fatigue evaluation of piping. Moreover, cycle counting in the fatigue evaluation was examined for further progress of the code case.

A Creep Buckling Design Method of Elliptical Heads Based on the External Pressure Chart

The buckling design criteria of elliptical heads in ASME VIII-1, ASME NH, and RCC-MRx are reviewed and compared. Accordingly, an external pressure chart (EPC) based buckling design approach is developed for elliptical heads in the creep range. Results indicate that for instantaneous buckling design, RCC-MRx predicts higher allowable pressure compared with ASME NH, which is ascribed to the smaller design factor. The proposed method produces a similar result with that given by ASME VIII-1. By contrast, the proposed method leads to a reasonably conservative result with the factor n of 0.03 for the creep buckling design. While the simplified method in RCC-MRx provides an over-conservative solution.

A Study on Hydrogen Emission of Zirconium Hydride

The hydrogen emission of zirconium hydride at high temperature is a challenging issue for many researchers. The hydrogen emission content of zirconium hydride pins should be evaluated to confirm the application feasibility. The comparison of theory analysis and experiment data indicated that Richardson's law could offer a conservative result for calculating the hydrogen emission content of zirconium hydride pins at high temperature. Furthermore, the methods of preventing hydrogen loss should be developed for the purpose of extending the work temperature or time. The results showed that a ZrO2 layer prepared for zirconium hydride could not prevent hydrogen loss after exposure at 650 °C in an inert environment and ZrO2 transformed into Zr3O gradually due to the opposite movement of hydrogen and oxygen. Finally, a further improvement to prevent hydrogen loss was developed. The zirconium hydride with a ZrO2 layer in the cladding of He+CO2 exhibited no significant reduction of hydrogen content. It is helpful to prevent the hydrogen loss by increasing the oxygen potential on the outside of ZrO2 layer.

Research on the Application of Fen for Environmentally Assisted Fatigue Evaluation of the Austenitic SS Pipe Under Combined Transient Loads

Accumulative test data indicate that the effects of the light water reactor (LWR) environment could cause the fatigue resistance of primary pressure boundary components materials to be significantly reduced. Environmentally assisted fatigue (EAF) is the abbreviation of the environmentally assisted fatigue. In 2007, Nuclear Regulatory Commission (NRC) issued RG. 1.207. It was updated in 2014. And, it requires that the effects of LWR environment on the fatigue life reduction of metal components should be considered for new design plants. And it suggests to use environmental correction factor, Fen, to account for EAF. NRC regulation (NUREG), NUREG/CR-6909 (NRC, 2013, “Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials,” U.S. Nuclear Regulatory Commission, Argonne, IL, Standard no. NUREG/CR-6909), presents the detail Fen calculation formula. Fen is a function of temperature, strain rate, dissolved oxygen level in water, and sulfur content of the steel. Accordingly, Fen calculation will present a comparatively conservative result. Depending on the experience of the primary pressure boundary piping transient operation, Fen varies during each transient. More uncertainty and confusion are raised during the application of the Fen method. The research work in this paper includes: first, the typical character of piping thermal transient is derived based on the existing experience. Second, small specimen EAF tests are conducted depending on the above derived combined loading characters. Then effort is taken to improve the application of the Fen method for the combined multitransient loading conditions. And the results are compared with those of the lowest instantaneous Fen method and equalization of the weighted Fen method. Finally, a designed test plan is presented.

Robust H∞ control of neutral system for sampled-data dynamic positioning ships

This study focuses on the robust ${H}_{\infty }$ sampled-data control problem of neutral system for dynamic positioning (DP) ships. Using the input delay approach and a state-derivative control law, the ship DP system is turned into a neutral system with time-varying delays. By incorporating the delay-decomposition technique, Wirtinger-based integral inequality and an augmented Lyapunov–Krasovskii functional, less conservative result is derived for the resulting system. Sufficient conditions are established to determine the system’s asymptotical stability and achieve ${H}_{\infty }$ performance using Lyapunov stability theorems. Then the ${H}_{\infty }$ sampled-data controller is obtained by analyzing the stabilization conditions. Finally, simulation result is shown that the proposed method is effective.

Assessment of Equivalent Thickness Design Principles for Geosynthetic Reinforced Pavements by Way of Accelerated Testing

The Engineer Research and Development Center (ERDC) of the U.S. Army Corps of Engineers has performed multiple laboratory and full-scale evaluations of geosynthetic reinforced pavements. One result from early geosynthetic reinforced pavement evaluations was a pavement design methodology implemented in ETL 1110-1-189: Use of Geogrids in Pavement Construction. Since that time, the evaluations have been primarily focused on comparing performance between varying types of geosynthetic products. While the studies have independently compared the discrete performance of single geosynthetic reinforced sections to unreinforced sections, a comprehensive analysis of available data has not been performed to validate or refine the implemented design methodology. The objective of this effort was to assemble available data from laboratory and full-scale testing conducted at ERDC for the primary purpose of assessing the flexible pavement design methodology presented in ETL 1110-1-189. Simplifying assumptions were made to allow comparison of varying loading and pavement structure conditions. This assessment found that the combined dataset supports the original design curve produced with the equivalent thickness methodology described in ETL 1110-1-189. The updated dataset would reduce the equivalent reinforced thickness by approximately 1.0-inches (25.4 mm) at unreinforced thicknesses less than 14 inches (356 mm), providing a slightly more conservative result. The adjusted data converged with the original equivalency chart at an unreinforced thickness of approximately 16 inches (406 mm).

Residual seismic capacity of ductile RC frame with wing walls based on full-scale loading test

In order to use a damaged building continuously after earthquake, owners and/or stakeholders need to understand residual seismic capacity of the building. In Japan, a method to evaluate residual seismic capacity for damaged buildings had been developed. In order to evaluate residual seismic capacity of damaged building, the damage level of structural elements should be evaluated properly. This paper presents the results of damage analysis based on experimental data obtained from a full-scale static loading test [1] on a five-story reinforced concrete building tested at Building Research Institute. The damage rating for the specimens evaluated by the residual seismic capacity concept [3] was ”Moderate” or ”Heavy” at 0.5% and 1% building drift angle despite the structure maintaining horizontal load carrying capacity. This implies that the applied method gives a conservative result for ductile buildings, such as relatively new moment resisting frames designed after 1981. In order to apply the method used in this paper to new buildings, the damage evaluation method for structural elements should be advanced more in the future.