Journal of Pipeline Systems Engineering and Practice

Onshore buried steel pipeline infrastructure is a critical component of the fuel supply system. Pipeline failure due to seismic actions is socially, environmentally, and economically unacceptable and thus the design of pipelines in geohazard areas, such as fault crossings, remains a hot topic for the pipeline community. There is an intense research effort on the evaluation of the pipeline mechanical behavior and the strength verification at fault crossings. Still, some aspects need in-depth consideration concerning practical applications. A state-of-the-art review is presented on three critical analysis and design aspects, namely, the calculation of the design fault displacement via deterministic and probabilistic methods, the effect of numerical modeling parameters such as soil spring properties, and the alternative pipe protection measures in terms of availability, efficiency, and selection process. The critical review offers a thorough insight into what is available and how to employ it in design, assisting engineers and pipe operators in improving pipe safety.

The National Office of Water (ONEE) in Morocco reports that a many of the prestressed reinforced concrete pipes (PCCP) used to supply potable water in the semiarid region of the country have been deteriorating due to the corrosion of the prestressed wires. Moreover, in some cases, the PCCP degradation occurs within 1 year, which is typically less than their durability expectancy. This rapid development of corrosion in PCCP is due to the aggressiveness of the soil and also partly as a result of the cyclical wetting and drying exposure conditions in the region. In this study, the beneficial effects of fly ash (FA) incorporated in the mortar coatings of PCCP exposed to simulated aggressive soil (Errachidia soil) are evaluated. Two mortar coating mixes, F1 (0% of FA) and F2 (17% of FA), have been studied. The reinforced specimens were evaluated over a prolonged period of aggressive soil attack under 16 wetting drying cycles in the laboratory oven. The electrochemical techniques open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) made it possible to assess the protective capacity of the two mortar coatings. In addition, scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS) analyses were performed to examine the microstructure of mortar coating. The results indicate that the incorporation of FA in the mortar coating under wet/dry cycling increases their resistance. This is confirmed by the stability of the OCP in the area of uncertain corrosion probability and the increase in resistance of the mortar (${\mathrm{R}}_{\mathrm{m}}$) and charge transfer resistance (${\mathrm{R}}_{\mathrm{dl}}$), approximately 82% and 90%, respectively. Meanwhile, the control mortar ${\mathrm{R}}_{\mathrm{m}}$ increased only by 27% and the ${\mathrm{R}}_{\mathrm{dl}}$ declined by 62% from 0 cycles to 16 cycles. In addition, the results of SEM-EDS analysis, chloride ion penetration depth, and visual inspection were in agreement with the electrochemical results.

Flow resistance is a critical calculation parameter in hydraulic engineering. In this study, the roughness coefficient of a circular drainage pipe with sedimentation was investigated under open-channel flow conditions using experimental measurements and numerical calculations. The ratio of the height of the sediment placed in the pipe to the diameter was defined as the sedimentation degree. The Manning roughness coefficient ($n$) was determined for pipes with different sedimentation degrees. Moreover, numerical simulations were performed for circular pipes with diameters of 0.152 m and a slope of 0.003, with discharges varying between 1 and $8\mathrm{L}/\mathrm{s}$. The results of the numerical calculations were validated in terms of the water surface and Manning’s $n$ using the corresponding experimental data. Accordingly, an equation in the form of the Moody formula was proposed to estimate the roughness coefficient. Subsequently, the predicted Manning roughness coefficient obtained through the proposed equation was compared with independent experimental results. The results indicate that the equation accurately predicts Manning’s $n$ in a pipe with sedimentation, which can provide a theoretical basis for the design of drainage pipelines.

Inductive heating with high-voltage cables reduces the risk of hydrate formation by raising the temperature of the production fluid in pipelines. Heating the pipeline results in losing a certain fraction of the heat to the surrounding soil through conduction- or convection-dominated flow through the soil. However, the amount of heat lost in conduction versus convection and the transition from conduction- to convection-dominated heat loss remains unknown. Soil permeability, temperature gradient between cable and mudline, and burial depth all influence the mode of heat transfer and the amount of heat lost. We studied the dominant mode of heat transfer in pipelines with inductive heating using 2D finite difference analysis under different soil and environmental conditions. Low permeability soils primarily exhibit conductive heat transfer, thus losing minimum heat to the surrounding soil. In contrast, in highly permeable soils convective flow drives a significant fraction of the heat away from the pipeline and towards the ground surface, barely heating the fluid in the pipe. We identified a critical Rayleigh-Darcy number (1) as the controlling value separating conduction- and convection-dominated heat transfer. An increase in burial depth reduces the heating efficiency in convection-dominated high permeability soils, while it has no effect in conduction-dominated low permeability soils.

Water distribution network (WDN) leakage is estimated to account for more than 20% of potable water in the United States. Because existing leakage detection practices are mainly laborious or require excessive budget allocation, novel model-based techniques have become prevalent by employing smart meters. Specifically, incorporating machine learning and metaheuristic optimization methods into such model-based approaches to predict water pipeline leakage is one of the state-of-the-art approaches. This paper presents a predictive leakage detection approach by leveraging advanced metering infrastructure (AMI) and cyber-monitoring data. Primarily, the synchronous collection of consumption and monitoring data (i.e., flow and pressure) constitutes the proposed predictive tool in a combinative framework of genetic algorithms (GA) and particle swarm optimization (PSO). The time-consuming EPANET 2.2 simulation toolkit in MATLAB is circumvented by a set of trained artificial neural networks (ANNs). Sensitivity analyses are conducted to investigate the sensitivity of the proposed leakage prediction approach to multiple parameters. Ultimately, the number and location of the flow and pressure monitoring stations are optimized using maximum sensor availability thresholds. Mean absolute percentage error (MAPE) is employed to measure the model’s accuracy. The proposed predictive tool offers insightful horizons on how considerable background leakage can be detected and prioritized without using labor-intensive, costly methods.

In pipe jacking projects, there are several factors that could influence construction efficiency. Pipe dimensions are one of the main ones that affect the cost and safety of pipe jacking operations. However, the main factors influencing pipeline stability and the maximum allowable jacking length, which usually is called the critical jacking length, are rarely explored. In this paper, three-dimensional finite-element models were conducted to investigate the factors influencing the critical jacking length during pipe jacking, including pipe dimensions, soil specifications, buried depth, and overcut values using commercially available software. The critical jacking length of a steel pipe in an alluvial soil was estimated using the displacement control method, and the probable failure modes of steel pipes were determined. Two cases were selected to compare the pipeline stresses with field-measured data to validate the numerical results. The results suggested the developed model could estimate the critical jacking length based on the site characteristics and pipeline specifications, and a critical jacking length surface could be presented for each site based on the site properties, which would be beneficial to select required pipe segment dimensions at the preliminary design steps.

Abstract

Leakage in underground water pipes has become critical because of increasing water demand. Many studies have been conducted based on the knowledge of soil–water interaction, but few of them have investigated the internal erosion and possible zones forming around cracks as a result of leakage. This experimental investigation set out to achieve a better understanding of the mentioned problem. An unplasticized PVC pipe with a longitudinal crack was installed in a box with different types of soil, then water was flowed through the pipe. The aim was to determine the geometry of the zones possibly forming around the crack. The observation was made possible by installing the pipe beside a glass wall situated on the front face. Two zones (fluidization and mobile bed) with different directions that were geometrically different with soil types and water head pressures were observed. The effects of soil properties [e.g., median diameter ($D_{50}$), Atterberg limits, porosity, and hydraulic conductivity] were also determined, and their relationships with the height, width, and maximum cross-sectional area of the mentioned zones were studied. The results demonstrated that the maximum height and maximum area of the zones were strongly correlated with water pressure.

Practical Applications

The significance of water in all aspects of human life is undeniable. Nowadays, a huge amount of water is wasted due to various reasons such as water loss from damaged parts of water distribution systems. The amount of leaking water can be impacted by factors including the surrounding environment, which is soil for underground pipelines. In addition, research has shown occurrence of fluidization phenomenon in which water and soil mixture around the leakage position flow in a confined area. Every underground infrastructure, including the leaking pipe, situated in the fluidized area can be affected and damaged. Knowing the mechanism of fluidization and factors affecting this area can thus help prevent underground facilities from damage. This experimental investigation examined the effects of pressure on the shape and size of zones around the leakage position. Furthermore, changes in the geometry of the mentioned area were studied by different types of surrounding soil.

Reliability assessment plays a significant role in the planning, design, and operation of water distribution systems (WDS). Herein, pressure, flow, chlorine concentration, and water age are simulated by continuity, energy, and transport equations; and hydraulic, water quality, and system reliability assessments are proposed based on a comparison between simulated hydraulic and water quality conditions and the desired service level. Because the independent parameters in hydraulic and water quality simulations cannot be estimated accurately, a hydraulic and water quality reliability assessment based on Monte Carlo simulation was applied to a network under three uncertain levels under steady- and unsteady-states. The effects of uncertain parameters on hydraulic and water quality reliability under steady- and unsteady-states were evaluated and compared to obtain the most significant parameters. The results indicated that the mean hydraulic reliability decreases with an increase in the uncertainty level for various nodes under steady- and unsteady-states, while the regulation is not suitable for water quality reliability. Pipe diameters have the most significant effects on hydraulic reliability under steady-state conditions, and mean hydraulic reliability under unsteady-state conditions. Nodal demand, bulk decay coefficient, and wall decay coefficient have effects on water quality reliability under steady-state conditions, while the roughness coefficient and pipe diameter also have effects on mean water quality reliability under unsteady-state condition. The results obtained can give managers more information about network reliability under uncertain conditions.

Abstract

The fierce positive pressure problem at the bottom of a building drainage pipe system can cause building discharge backflow or indoor environmental pollution. Full-scale discharge experiments on the vent pipe bottom position were conducted in a 60-m-high experimental tower. The vent pipe bottom connected to the drainage stack and to the horizontal main was examined in an H-joint connected dual-stack system and a circuit vent drainage pipe system. Pressure limit values, water seal losses of sanitary fixtures, and airflow rates were investigated to determine system discharge capacities. The maximum discharge flow rate of the H-joint connected dual-stack system with the vent pipe bottom connected to the drainage stack was $7.5\mathrm{L}/\mathrm{s}$. In comparison, the maximum discharge flow rate of the improved system was increased to $9.5\mathrm{L}/\mathrm{s}$. For the circuit vent drainage pipe system, the improved bottom connection mode increased the discharge capacity by 200%.

Abstract

A vent pipe end connected to the horizontal main could increase a pipe system’s discharge capacity, which means the system design could adopt a smaller pipe size than usual. This improved connection mode minimizes the material of building drainage pipe systems and reduces associated engineering costs.

Pipeline crossings influence the soil water and heat distribution and then affect soil shear strength parameters, including internal friction angle and cohesion. Soil melting reduces the shear strength. Slope instability, which could lead to pipeline exposure, deformation, and so on, may occur under rainfall and soil gravity. Thus the stability of permafrost slopes with a pipeline crossing was studied. The safe slope angle that the pipeline could cross without protective measures was determined. Based on the strength reduction method and Drucker-Prager elastoplastic model, a universal finite-element model of slope and pipeline was established. The effects of water content and slope angle on the stability of permafrost slope were studied. The results show that March and April are the most stable months of the year, whereas September and October are the most dangerous months. The slope angle significantly influences the permafrost slope stability; the slope angle must be lower than 30°, and protective measures are necessary when the slope is greater than 30°. The increase of water content decreases the slope stability.

In this study, the possibility of installing turboexpanders instead of throttle valves was investigated and analyzed using Aspen HYSYS and Aspen Capital Estimator version 12.1. The optimization and energy saving cases were studied for maximum power or electrical energy generation as well as liquefied natural gas (LNG) production. Three case studies with various refrigeration cycles were evaluated according to economic considerations. It was found that the cases of power generation and LNG production were the best cases for energy recovery in gas pressure–reduction stations. The capital cost and rate of return (ROR) of this process were $232.2 million and 75%, respectively. The employed technique and developed process can be used for the optimization of energy in gas pressure–reduction stations.

The transportation sector is an integral part of the US economy. It employs millions of people and incorporates 8.9% of the nation’s economic activity as measured by gross domestic product. According to the US Department of Transportation, about 48,280 km (30,000 mi) of the busiest highways will be jammed daily by 2040, which requires an essential increase in the capacity of the transportation system. Underground logistics transportation (ULT) is a class of automated transportation systems in which vehicles carry freight through tunnels and pipelines between intermodal terminals. Construction of intermodal ULT systems through tunnels or pipelines can increase the existing shipping network capacity. Therefore, considering the intermodal terminal as a substantial component of the ULT, it is important to evaluate the present terminal’s capacity by studying the effect of different operational components on terminal performance. The objective of this study is to develop a framework for optimizing the capacity of intermodal ULT terminals through the discrete event simulation (DES) model. To optimize terminal operations, a base model and two different scenarios are developed and simulated within which the variations of performance indicators are tested. Outputs from all three models are compared to the ULT annual expected shipped containers and the results from the two latter scenarios show 34 and 59% improvements in the number of shipped containers, respectively.

Thermal stress analysis is an integral part of the design and integrity assessment of buried pipelines. Pipe bends can be subjected to significant cross-sectional deformations due to bending moments induced by thermal cycles, compared to straight pipes, and therefore are the most crucial component of the pipeline’s structural integrity. Fatigue fracture, which is the primary failure mode in pipelines under the thermal cycle, may occur at the crown region of the pipe bend in the form of a longitudinal crack. This specific failure pattern is primarily the result of excessive circumferential stress that may develop in the crown region of a pipe bend. The present paper suggests a novel approach to reduce the stress range at the crown region of pipe bends using carbon fiber-reinforced polymer (CFRP) wraps. This approach has been used in the pipeline industry to reinforce and repair corroded pipes. However, a very limited study on the use of CFRP wrap to enhance the mechanical behavior of undamaged pipe bends is available in the literature. This study employs an advanced finite element (FE) method to investigate the performance of buried pipe bends reinforced with CFRP composite wraps and subjected to thermal expansion-induced bending moment. A combined beam and shell-based FE model has been used in this study to ensure reasonable accuracy and remarkable computational efficiency for engineering practice. The FE results show that a 6 mm CFRP wrap around the pipe bend can decrease the von-Mises stress imposed by thermal expansion by up to 27.4%. In short, reinforcing pipe bends with CFRP wrap has a strong potential to decrease the stress range imposed in the pipe bend under thermal expansion-induced moments and consequently prevent fatigue failure in pipe bends.

This paper describes an approach enabling well-supported, rational decisions about when to deploy inspection and condition assessment for high-consequence water pipelines, which techniques and technologies to select, and when to stop assessing pipeline condition and plan for replacement. The proposed probabilistic approach considers the entire life-cycle cost of the pipeline, accounting for deterioration rate, failure consequences, cost of rehabilitation, accuracy and cost of inspection/condition assessment, cost of emergency repair versus planned intervention, and cost of total pipeline replacement. The approach allows combining expert opinion (semi-informative assessment) with hard field data (historical failures, and inspection and condition assessment results) into a robust, well-informed, and reproducible assessment of pipeline deterioration rate. The approach also allows pipeline owners to incorporate new field data, which in turns permits continually updating the assessment of the pipeline condition. The approach also estimates the remaining life of the pipeline, in anticipation of its complete replacement. End-of-life is defined as the time at which it is no longer economical to continue repair or rehabilitation, and full replacement is economically preferable.

The structural integrity of buried pipelines is often threatened by permanent ground deformation (PGD) within the pipeline route. Oil and gas transmission steel pipelines, which usually traverse several kilometers, are mostly buried. Inevitably, they can cross over areas with considerable geohazard concerns due to different soil types or extreme topographies. PGD usually occurs with various patterns, magnitudes, and directions relative to the pipeline axis with varying influences on the structural performance of buried pipelines. This paper discusses a comprehensive investigation of the effect of PGD patterns on the strain demand of pressurized buried continuous steel pipelines subjected to ground movement. The maximum strains induced in buried pipelines by longitudinal and transverse ground displacements of different patterns are presented. A three-dimensional nonlinear beam-Winkler spring finite-element (FE) analysis is used. The FE model accounts for the elastic-plastic behavior of pipe and nonlinear pipe-soil interaction. A straight NPS 42 Grade X70 steel pipeline with a wall thickness of 14.3 mm was considered and assumed to be fully embedded in two different soil types (stiff clay and dense sand). The pressurized pipeline was subjected to six different PGD patterns (i.e., sinusoidal, trapezoidal, ridge, ramp, block, and step) of three different magnitudes (1.0, 2.0, and 3.0 m). Each pattern was applied in the transverse (vertical and lateral) and longitudinal directions. The results show a significant variation in the strain demand of buried pipelines subjected to the various PGD patterns. The longitudinal strain induced in a pipeline due to PGD of the same magnitude but different patterns varies by up to 752%. Moreover, stiff clay is found to impose more strain on buried pipelines than dense sand. The results presented in this paper can be a useful reference in the safety assessment of straight sections of a similar buried pipeline under PGD.

In old distribution networks, water leaks cause significant losses, which can reach 50%; therefore, locating and correcting these leaks is crucial and is an eco-friendly measure, especially in places with few water sources. In this paper, a novel electrical technique is proposed to locate leaks in underground pipelines made of electrical insulated materials. This technique is based on the difference in the electrical resistance between the water and the pipe environment. It locates leaks by specifying the location that gives the greatest current value or the smallest resistance value in a circuit between a fixed reference point on a water pipe and a moving point on the surface. When the moving point is above a water leak point, the electrical resistance is minimum, that is, the location that gives the minimum electrical resistance or the maximum current is above the water leak point. This technique is advantageous because it is easy to implement, requires simple equipment, and can be used to detect leaks, however small, instantly at the start of the leak. Simulation and experimental studies on the effect of several parameters affecting the precision of this technique were also performed. Voltage values of 10, 20, and 30 V at a frequency of 1,000 Hz, two PVC tubes with diameters of 4 and 6 cm, and earth resistivity values of 100, 250, and $\mathrm{10,000}\mathrm{\Omega }·\mathrm{m}$ were used. The experiments showed that the higher the voltage, the better the accuracy, and the same goes for the pipe diameter. As for the soil resistivity, the middle values give the best precision. The experimental measurements and the simulation study, using COMSOL Multiphysics software, validated this technique.

Abstract

Stochastic population-based metaheuristic algorithms have been widely used to design water distribution networks (WDNs). The present study introduces one of its kind, the krill herd algorithm (KHA), a novel swarm intelligence-based metaheuristic. Demonstrating KHA application to WDN design, the study proposes its enhanced version to improve its convergence precision. Consequently, combining the fine-tuned mechanism of KHA with the EPANET 2.2 simulation software, the fine-tuned KHA (FIT-KHA) model is formulated and checked for its efficiency in handling the WDN design problem. Because three benchmark problems (new and rehabilitation WDNs) of different dimensions are considered, the significance of the algorithm control parameters concerning the network size is studied. From sensitivity analysis, the time step factor, number of krill, and maximum iteration size are found to influence the algorithm performance. Their optimal values followed an increasing trend with the network size. The computational results reinforce a superior search exploitation ability of the FIT-KHA. Importantly, the results exhibit a better computational efficiency of KHA over most of the reported metaheuristic algorithms. Then, the performance state of optimally designed WDN under hydraulic (demand, roughness coefficient variations) and mechanical (single- and two-pipe failure) uncertain scenarios is studied. Besides reliability and surrogate measures, multiaspect metrics based on adequacy and equity are evaluated to assess the network’s performance. The WDNs are observed to be more susceptible to demand uncertainties over roughness coefficient variation. At higher states of mechanical (pipe) failure scenarios, especially, the equity of the WDN is disturbed compared to the adequacy, except for rehabilitated WDN. Certainly, the performance study manifests that the reliability measure that truly presents the WDNs performance is the function of network type. While proposing KHA as an effective alternative optimization tool, the study suggests a prior performance study to choose an appropriate metric to formulate a reliability-based multiobjective framework for the robust design of WDNs.

Abstract

Water distribution networks (WDNs) form an essential infrastructure of the society conveying potable water. Considering the nondeterministic polynomial-time hard (NP-Hard) nature of the WDN design problem, extensive research has been conducted proposing various optimization algorithms for its design. The present study introduces a novel swarm intelligence-based metaheuristic optimization technique, the krill herd algorithm (KHA). Demonstrating the excellent exploitation ability of KHA, the study formulated its enhanced version, the fine-tuned KHA (FIT-KHA) model. Its computational efficiency over other reported algorithms in handling the new and rehabilitated WDNs of different dimensions is demonstrated. Considering the FIT-KHA model optimal designs, the benchmark WDNs performance state under hydraulic (demand, roughness coefficient variations) and mechanical (single- and two-pipe failures) uncertain scenarios are also studied. The WDNs are more susceptible to demand uncertainties and higher states of mechanical (pipe) failure scenarios over roughness coefficient variation. The reliability measure that truly presents the WDNs performance is the function of network type. Hence, proposing KHA as an effective alternative optimization tool, the study suggests a prior performance study to choose an appropriate metric to formulate a reliability-based multiobjective framework for the robust design of WDNs.

Abstract

Although essential contributions have been made to the reliability analysis of corroded pipelines, the interacting effect between adjacent corrosion defects is rarely considered, let alone the effects of the corrosion depth and steel grade on the interacting effect. This paper proposes a new reliability method to fill the gap. First, the finite-element method and regression analysis were applied to investigate how the corrosion depth and steel grade impact the interacting effect and develop new interaction rules. Second, the new interaction rule, burst pressure model, Monte Carlo simulation (MCS), sensitivity analysis, feature scaling, and artificial neural network (ANN) were integrated to predict reliability. The proposed method combines several approaches to achieve a more accurate and efficient reliability estimation of pipelines with multiple corrosion defects than conventional assessment methods. An example is given to demonstrate the method. Results show that the limit spacing distance grows as the corrosion depth increases. The growth of the limit spacing distance of the X80 pipeline is more significant than that of the X65 pipeline. Existing interaction rules introduce conservatism to the prediction of the limit spacing distance. Two new interaction rules were developed and can realize better prediction accuracy by considering the corrosion depth and steel grade. Besides, the interacting effect significantly affects the maintenance time. The maintenance time lag between the X65 pipeline ignoring and considering the interacting effect is about 7.5 years. Different interaction rules result in different reliability descending paths. Because the new interaction rule was developed for this case, it could provide a more accurate reliability analysis. The trained ANN shows excellent prediction accuracy and high computing efficiency. The mean squared error in the reliability predicted by the ANN is $2.4\times {10}^{-6}$. The elapsed time of the ANN prediction is about 50 times shorter than that of the MCS.

Practical Applications

In engineering practice, corrosion defects usually occur in patches, and the interacting effect between adjacent defects impairs the structural reliability of corroded pipelines. The corrosion depth and steel grade are found to significantly affect the interacting effect and limit spacing distance. The new interaction rules can be applied to achieve a more accurate limit spacing distance estimation by considering the effects of the corrosion depth and steel grade. The interacting effect plays a vital role in the reliability analysis of corroded pipelines. The integrated reliability method proposed in this paper considers the interacting effect and interaction rule. In practical application, once the pipeline and defect information, such as wall thickness and corrosion depth, is gathered, the proposed method can be used to realize a more accurate and effective reliability analysis of pipelines with multiple corrosion defects. Thus, the proposed reliability method and results of this paper are beneficial for the integrity management of corroded pipelines.

The amount of natural gas consumption varies in different seasons. Demand for natural gas reaches its peak in winter because it is exceedingly used at homes and there is misbalance between the supply and demand of this gas. Thus, it is essential to use a gaseous alternative fuel to keep on transferring gas to consumers (homes, industries, and power plants), prevent cutting gas to industrial centers and power plants at the consumption peak, and also compensate for gas deficits and cover consumption excess in cold seasons. In consequence, this research aims to scrutinize the effects of injecting gaseous hydrocarbons heavier than methane as a gaseous alternative fuel on transferring lines and the equipment of the gas compressor station (separator, compressor, and air cooler). In this simulation, a part of the Iran Gas Trunkline (IGAT) VIII from the output of the gas compressor station of Kheirgoo to the input of the gas compressor station of Khavaran with a length of 245 km and with gas compressor stations Khonj and Jahrom on the way has been considered. The simulation results indicated that the injection of gaseous hydrocarbons heavier than methane does not affect the operation of pipeline and the separator, but it influences the efficient consumption of compressor and air cooler. The objective of this research can be achieved by the presented alternatives and making any or the least changes in the structure of the pipeline and the equipment of gas compressor station.

Wind-resistant performance is a major concern in the design and operation of pipeline suspension bridges. The mean aerodynamic force coefficients (MAFCs) are essential parameters for quantifying the wind loads on a bridge. However, a systematic investigation of the MAFCs of typical pipeline suspension bridge girders is unavailable. Specifically, the effects of design parameters (perforation rate of grate plates, horizontal spacing between pipelines, vertical spacing between pipelines, pipeline number, pipeline diameter, and pipeline surface roughness) and Reynolds number on MAFCs remain to be investigated. This study systematically investigated the MAFCs of three typical pipeline suspension bridge girders in wind tunnel experiments. The galloping stabilities of these girders were examined based on the quasi-steady galloping theory. The experimental results show that the effect of pipeline surface roughness on the Reynolds number effect of drag force coefficient is similar to that on the Reynolds number effect of a circular cylinder. Closing the grate plates may deteriorate the galloping performance of a bridge girder, whereas increasing the pipeline surface roughness may strengthen the galloping performance of a bridge girder. Unlike parallel circular cylinders, the horizontal spacing between pipelines slightly affects the MAFCs. Optimizing the vertical spacing between the pipelines can significantly reduce the MAFCs. In addition, optimizing the shape and roughness of the pipeline can reduce the lift force and pitching moment, and optimizing the shape of guardrails and truss stiffening girder can reduce the drag force. These research results can provide a basis for quantifying the aerodynamic loads and a reference for the wind-resistant design of pipeline suspension bridges with similar bridge girders.

This paper proposes a physical model–based approach for predicting failures of concrete stormwater pipelines considering corrosion of reinforcing steel bars. Three failure modes, namely flexure failure, shear failure, and cracking failure, were examined over the service life of stormwater pipes based on a widely accepted corrosion model for rebars in concrete. Random stochastic processes were utilized to approximate the load effects in the three failure modes, and the first passage probability theory with the exponential autocorrelation function was employed to conduct the probabilistic analysis over the lifetime of the stormwater pipes. A worked example was presented to demonstrate the application of the proposed approach and evaluate the effect of rebar corrosion on the failure probability of a stormwater pipe. It was found that the correlation lengths of the stochastic processes play a considerable role in the failure probabilities of each failure mode and the system. It was also found that the probability of system failure reduces with an increase in concrete cover thickness and a decrease in water-cement ratio of the concrete.

Pipe jacking, microtunneling, and pipe ramming are common trenchless techniques for installing pipelines or cables below the bed of watercourses. A tunnel boring machine (TBM) is also used for constructing pipelines with large diameters or tunnels underneath the bed of watercourses. Most pipeline and tunnel installation methods used for river crossings induce strong vibrations during construction and should be monitored to ensure pipeline integrity, canal bed stability, and steady flow characteristics. In this study, the effect of vibrations of a buried pipeline on canal bed morphology is experimentally explored. A total of 135 tests were conducted using different canal flow depths, Froude numbers, pipeline diameters, pipeline depths under the canal bed, and vibration amplitudes. Empirical formulas were deduced to estimate the canal bed deformation due to the vibrating buried pipeline. Results reveal that for the considered parameters, the burial depth of 2.4 times the pipe diameter reduced the deformed scour depth by up to 53%. The combined effect of flowing water in the canal and the pipe vibration causes undesirable change in the canal bed; therefore, using TBMs or pipe jacking in case of a dry canal whenever possible could be better.