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Oil and gas (O&G) pipelines are expensive assets that cross through both the ecologically sensitive and densely populated urban areas. The pipeline failure may have potentially significant consequences for both the natural and human environments. In order to maintain the integrity of O&G pipelines, inspection and maintenance processes should be governed by efficient policies. The objective of this paper is to conduct a state-of-the-art review of maintenance policies of O&G pipelines to investigate their advantages, limitations, and associated implementation issues. Maintenance policies can be categorised into corrective, preventive, predictive and proactive. Corrective maintenance policies (1940s) were based on the ‘repair when broke’ philosophy. Economic considerations shifted practice towards preventive maintenance (1970s to 1990s); later with improved inspection techniques and environmental regulations, predictive and proactive or risk-based maintenance (RBM) policies were developed. This review explicates different methodologies for RBM and related issues, e.g. uncertainties and variability, conservative assumptions, etc. Uncertainties associated with investigation and prediction of defects have been more frequently reported in the literature so far. Moreover, existing studies primarily focused on reducing the likelihood and cost of failure, whereas consideration of environmental factors in overall risk has been a relatively less addressed issue. [ABSTRACT FROM AUTHOR]

For the last few decades, concerns have repeatedly been raised about deteriorating water mains in Canada. Small to medium sized water utilities are generally impacted more due to lack of technical and financial resources. This paper presents a user-friendly life cycle cost (LCC) analysis-based decision support tool to help these utility managers to prioritize water mains rehabilitation or replacement (R/R) strategies. The deterioration curves for water mains of different materials and sizes have been developed based on their likelihood of failure. The proposed model is implemented for the water supply network of City of Kelowna (Canada). It compares the costs of various R/R scenarios for each pipe over its life cycle and suggests the most cost-effective decision to the managers to efficiently allocate their limited resources. [ABSTRACT FROM AUTHOR]

The current performance-based building design considers maximum interstorey drift (MISD) ratio as the main structural performance indicator. Observations from past earthquake and reported studies, however, have highlighted that residual interstory drift (RISD) ratio has become an important factor in assessing post-earthquake safety of buildings, and decision in economic feasibility of repair and reconstruction. Improving post-earthquake performance evaluation of buildings enables decision-makers prioritise repair and tag high-risk buildings. The MISD and RISD are subject to uncertainties and have non-linear relation with the input parameters. Thus, in this paper, analytical surrogate model of MISD and RISD ratios are developed using Gaussian process (GP). To show utility of the GP model, a new hybrid building system, cross laminated timber (CLT)–steel moment resisting frame hybrid system, was considered. The hybrid building was design for the seismicity of Vancouver, BC, and meets the current steel design code. For the GP surrogate model, the hybrid building input parameters considered were: infill pattern of the CLT, bracket spacing of the connection between the CLT and steel frame and panel thickness and strength of the CLT. In addition, sensitivity of four ground motion indicators was considered as surrogate input into the GP model: peak ground acceleration, ratio of peak ground acceleration/peak ground velocity, Arias intensity measure and significant duration. In general, the GP model showed good predictive performance of MISD and RISD ratios. In particular, the best predictions were obtained using the ratio of peak ground acceleration/peak ground velocity as a covariate. [ABSTRACT FROM AUTHOR]

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The law to promote the use of wood in the construction industry was announced by the Japanese government in 2010. As a result of this initiative, timber and timber-based hybrid buildings are increasingly used in public buildings. As the buildings are located in high seismic zone areas, however, validation of the current design guideline was of paramount importance. This paper reports the design and a shake table test of timber frame-reinforced concrete (RC) core hybrid systems. Three specimens (S1, S2, and S3) are tested: S1 and S2 are both one-story buildings with a nailed plywood floor (flexible diaphragm) and a rigid RC floor (rigid diaphragm), respectively. S3 is a two-story building with a nailed plywood floor. Each specimen is tested with increasing magnitude of earthquake loading. The shake table test results showed that the adopted design guideline is sufficient. At higher seismic loads, however, the prevalent plan irregularity induced higher torsional demand damage at the RC core and timber connection region. [ABSTRACT FROM AUTHOR]

Water utilities often rely on water main failure prediction models to develop an effective maintenance, rehabilitation and replacement (M/R/R) action plan. However, the understanding of water main failure becomes difficult due to various uncertainties. In this study, a Bayesian updating based water main failure prediction framework is developed to update the performance of the Bayesian Weibull proportional hazard (BWPHM) model. Applicability of the proposed framework is illustrated with modeling failure prediction of cast iron and ductile iron pipes of the water distribution network of the City of Calgary, Alberta, Canada. The Bayesian updating models have effectively improved the water main failure prediction whenever new data or information becomes available. The proposed framework can assess the model performance in the light of uncertain and evolving information and will help the water utility authorities to attain an acceptable level of service considering financial constraints. [ABSTRACT FROM AUTHOR]

In seismically active regions, the use of timber--reinforced concrete (RC) hybrid construction can overcome the structural limitations that occur with timber construction. This paper investigates three connections used in the timber frame--RC core hybrid system: (1) RC wall-timber beam connection, (2) timber column-base connection, and (3) timber beam-timber column connection. A series of monotonic and reverse-cyclic loading tests were conducted on three replicate connections. Salient features of each connection (i.e., stiffness, ductility, and energy dissipation) were computed from the monotonic loading test results and were used to set the backbone curve of the analytical Pinching4 hysteretic model. Furthermore, the Pinching4 hysteretic models were calibrated with the reverse-cyclic loading test results. Utility of the Pinching4 hysteretic models was shown with performance prediction of a portal frame test. The portal frame results showed good agreement between the finite element model using the calibrated Pinching4 hysteretic models and experimental test results. [ABSTRACT FROM AUTHOR]

Safety assessment of oil and gas (O&G) pipelines is necessary to prevent unwanted events that may cause catastrophic accidents and heavy financial losses. This study develops a safety assessment model for O&G pipeline failure by incorporating fuzzy logic into Bayesian belief network. Proposed fuzzy Bayesian belief network (FBBN) model explicitly represents dependencies of events, updating probabilities and representation of uncertain knowledge (such as randomness, vagueness and ignorance). The study highlights the utility of FBBN in safety analysis of O&G pipeline because of its flexible structure, allowing it to fit a wide variety of accident scenarios. The sensitivity analysis of the proposed model indicates that construction defect, overload, mechanical damage, bad installation and quality of worker are the most significant causes for the O&G pipeline failures. The research results can help owners of transmission and distribution pipeline companies and professionals to prepare preventive safety measures and allocate proper resources. [ABSTRACT FROM PUBLISHER]