Journal of Infrastructure Systems

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

This paper develops fragility functions and estimates of resilience indicators for aboveground storage tanks (ASTs) subjected to hurricanes, which can be efficiently applied to all the tanks in a regional portfolio of ASTs to assess their hurricane performance. Fragility and resilience assessment of a portfolio of ASTs is essential for planning mitigation strategies at the regional level and at the level of individual structures. Recently, studies have started assessing the fragility of ASTs under hurricane loads; most of the existing studies are focused on a specific AST type and a specific hurricane-related hazard. However, in order to facilitate performance assessment of an entire portfolio of ASTs, fragility functions for different types of tanks and hazards are necessary, which are lacking in the literature. Furthermore, estimates for resilience indicators such as repair costs and downtime are also not available in the literature. Therefore, to address these gaps, this study first develops fragility functions for different types of ASTs subjected to hurricane winds and storm surge. Next, estimates of repair costs and downtime are defined for different failure modes of ASTs by adapting costs and downtime for similar failure modes from different hazards. The fragility functions, repair costs, and downtime estimates developed herein are used to assess the performance of ASTs in the Houston Ship Chanel (HSC), which houses more than 4,500 ASTs, for two synthetic hurricane scenarios corresponding to 100 and 250-year return period events. For both scenarios, 100,000 Monte Carlo simulations are performed for each tank to determine the failure probability, repair costs, and downtime for all ASTs while propagating uncertainties in the fill level and density of contents stored in all ASTs. Furthermore, the influence of anchoring all tanks as a storm surge risk mitigation strategy on the performance of ASTs is also evaluated. The results provide several insights into the performance of tanks in the Houston Ship Channel during the two hurricanes: the tanks are not vulnerable to hurricane winds; however, failures are observed due to storm surge, which highlights the need for storm surge mitigation measures for the Houston Ship Channel region. Furthermore, tanks with the highest failure probability do not necessarily lead to high spill volumes or repair costs. Moreover, even minimum anchoring is observed to be effective in significantly reducing the spill volume and repair costs.

Cast iron pipes were widely used in water distribution networks before the 1960s and the majority of them have become aged and deteriorated with corrosion, which has been identified as one of the most common mechanisms of pipe failures. To have an optimum strategy for repair and/or replacement in the management of pipe assets, accurate prediction of the service life of the pipes is essential. This paper attempts to propose a method for reliability analysis and service life prediction for corrosion-affected pipes. Both loss of strength and fracture toughness of the pipe are considered in assessing pipe failures using a system reliability method. A sensitivity analysis is also carried out to identify those factors that affect the pipe behavior and failure the most. It is found in the paper that the probability of pipe failure is considerably greater when multifailure modes are considered as a system than when each failure mode is considered individually. It is also found that the likelihood of pipe failure due to loss of toughness is more than three times higher than that due to loss of strength. The paper concludes that multifailure modes should be considered in predicting pipe service life using a system reliability method as proposed here. The proposed method can improve the ability of the water industry in predicting and preventing catastrophic failures of the water pipes.

Most water distribution systems worldwide are deteriorating rapidly, while their rehabilitation costs are on the rise. Maintaining water networks in a proper condition under a tight budget puts extra pressure on municipalities and triggers the need for a proper performance assessment. This research therefore aims at developing an Integrated Water Networks Performance Assessment (I-WNPA) model to assess the performance of water networks. It also presents a functional (physical, operational, quality of service, and environmental) and global (or total) performance index scale of different performance states, the description of each state and recommended intervention actions (long term, short term, or immediate). The model encompasses three main phases for utilizing the fuzzy analytic network process (FANP) to calculate the weights of functional performance criteria of the components in the first phase. It also uses both the preference ranking organization method of enrichment evaluation (PROMETHEE) and the simple multiattribute utility theory (MAUT) to compute the functional and global performance indices of the network components. Then, the probability-of-failure–based integration method is developed to integrate the component indices and to obtain the segment performance index (SPI). The topological clustering is adopted to integrate SPI to obtain the entire network index, using the topological chart of the network and the connectivity ranked matrix. In this research, data are obtained from questionnaires and case study databases. The proposed model is demonstrated via the data covering water subnetwork in the city of Montreal. The results are well aligned with Montreal water services assessment as follows: Excellent for 16 pipes and 49 accessories, good for 32 pipes, medium for 5 pipes and 8 accessories, and poor for 21 accessories. The results also show that the analyzed subnetwork is in a medium state. These results are used to identify and prioritize the most vulnerable components, subnetworks, or the entire network, and subsequently to identify the performance improvements required. The model can be linked to other models, such as rehabilitation planning and budget allocation. This approach suits any unidirectional (one-way flow) water network, and it can be adopted to support the performance assessment of any water network by considering hydraulic analysis and automation means. It can also be adopted by other infrastructure systems, such as sewer networks and subway systems, when suitable indicators are defined.

In recent years, flooding has caused disruptions to road management by significantly increasing rehabilitation costs. To date, there is very limited literature addressing the rapid deterioration of pavements immediately after a flooding event. This paper presents a state-of-the-art review of the literature on assessment and modeling deterioration of flood-affected pavements. Twenty peer-reviewed journal articles and conference papers and nine published reports are reviewed. Very few studies have attempted to incorporate flooding events on pavement condition. The critical review of the literature discusses the contributions and limitations in the assessment of flood-affected pavements to date. It also discusses the research conducted on the development of new deterioration models specifically for flood-affected pavements and the importance of developing such models for the road management system. Because there is no deterioration models for rutting and roughness of flood-affected pavements, this paper also presents two mechanistic-empirical deterministic based models for deterioration of rutting and roughness of flood-affected pavements. These models are sufficient to be used by other road agencies after calibrating for local road conditions. The outcomes of this paper will guide future research and help to understand the impact of flooding events on rapid deterioration of pavements. The newly developed deterioration models will help road agencies make effective decisions for the rehabilitation and management of flood-affected pavements.