Infrastructures

18 pages, 3756 KiB

Open AccessArticle

Characterisation of Permanent Deformation Behaviour of Asphalt Mix Based on a Combined Elastic Plastic (CEP) Parameter

by Abhirup B. Roy-Chowdhury, Mofreh F. Saleh and Miguel Moyers-Gonzalez

Infrastructures 2021, 6(12), 183; https://doi.org/10.3390/infrastructures6120183 - 20 Dec 2021

Cited by 2 | Viewed by 2953

Permanent deformation or rutting is a major mode of failure in Hot Mix Asphalt (HMA) pavements. The binder used in the asphalt mixture plays an important role in the rutting resistance performance of the mixture. Currently, the Superpave rutting parameter and a more [...] Read more.

Permanent deformation or rutting is a major mode of failure in Hot Mix Asphalt (HMA) pavements. The binder used in the asphalt mixture plays an important role in the rutting resistance performance of the mixture. Currently, the Superpave rutting parameter and a more advanced test called multiple stress creep and recovery (MSCR) are the most widely used tests for rutting characterisation of asphalt binders. However, they both have their own merits and demerits. This study was undertaken to introduce a combined Elastic-Plastic (CEP) parameter as an additional binder rheological rutting parameters. The study also aimed at investigating the applicability and potential of this parameter to supplement the existing binder rheological parameters to characterise the properties of asphalt binder related to HMA rutting performance. Additionally, the correlations of the binder rheological parameters with the asphalt mix rutting parameters generated by the dynamic creep and the dynamic modulus tests were investigated. For the polymer-modified binders, Styrene-Butadiene-Styrene (SBS) was added to the PG 70-16 binder at two concentration levels (4, and 6% by the mass of the binder). A dense-graded HMA AC 14 was tested in the Dynamic Modulus (DM) and Dynamic Creep (DC) tests for evaluating the rutting performance. The CEP parameter was found to be much more reliable than the traditional G*/sin (δ) and the non-recoverable creep compliance (J_nr) parameters for evaluating the rutting behaviour of polymer modified asphalt binders, evident from better correlations of CEP with the asphalt mix performance. Unlike Jnr, the CEP parameter revealed a wider range of values, which is comparable with asphalt mixture test results. Full article

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20 pages, 2413 KiB

Open AccessArticle

Developing Evaluation Framework for Intelligent Transport System on Public Transportation in Bangkok Metropolitan Regions Using Fuzzy AHP

by Aoonrot Choosakun and Chunho Yeom

Infrastructures 2021, 6(12), 182; https://doi.org/10.3390/infrastructures6120182 - 20 Dec 2021

Cited by 11 | Viewed by 3456

Abstract

Public transportation has been encouraged as a significant solution to overcome traffic congestion. An advanced technology, known as advanced public transport system (APTS), was introduced to enhance the effectiveness of public transportation. To support appropriate decisions on selecting application development, significant indicators representing [...] Read more.

Public transportation has been encouraged as a significant solution to overcome traffic congestion. An advanced technology, known as advanced public transport system (APTS), was introduced to enhance the effectiveness of public transportation. To support appropriate decisions on selecting application development, significant indicators representing the impacts of the proposed projects are highlighted. This study aims to determine the desirable indicators of developing APTS to achieve smart mobility using the fuzzy Analytical Hierarchy Process (fuzzy AHP) method and allocating weights to each indicator. The perception of a group of intelligent transport system (ITS) experts from three sectors in the Bangkok Metropolitan Regions (BMR) was examined to conduct a fuzzy AHP pairwise comparison. The ranking of 21 indicators categorized within six dimensions in accordance with the specific ITS master plan relating to APTS development is presented. The result presented that the safety dimension obtained the highest rank, and the three most important weight indicators are traffic accident reduction relating to public transportation, smart public transport network density and waiting time for public transportation. In addition, the perspectives towards APTS development and assessment framework development in BMR is highlighted to revise impediment of regulation and encourage integration among stakeholders. Then, the approaches of the APTS evaluation framework in BMR are proposed. Full article

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13 pages, 1114 KiB

Open AccessArticle

Gene-Expression Programming-Based Model for Estimating the Compressive Strength of Cement-Fly Ash Stabilized Soil and Parametric Study

by Van-Ngoc Pham, Erwin Oh and Dominic E. L. Ong

Infrastructures 2021, 6(12), 181; https://doi.org/10.3390/infrastructures6120181 - 20 Dec 2021

Cited by 7 | Viewed by 2929

Abstract

The study aims to develop a reliable model using gene-expression programming (GEP) technique for estimating the unconfined compressive strength (UCS) of soil stabilization by cement and fly ash. The model considered the effects of several parameters, including the fly ash characteristics [...] Read more.

The study aims to develop a reliable model using gene-expression programming (GEP) technique for estimating the unconfined compressive strength (UCS) of soil stabilization by cement and fly ash. The model considered the effects of several parameters, including the fly ash characteristics such as calcium oxide (CaO) content, CaO/SiO₂ ratio, and loss of ignition. The research results show that the proposed model demonstrates superior performance with a high correlation coefficient (R > 0.955) and low errors. Therefore, the model could be confidently applied in practice for a variety of fly ash qualities. Besides, the parametric study was conducted to examine the effect of fly ash characteristics on the strength of soil stabilization. The study indicates that if the fly ash contains a high amount of calcium oxide, the strength of fly ash stabilized soil is significant. In addition, fly ash could be used in combination with cement to increase the strength of the mixture. A fly ash replacement ratio is suggested from 0.19 to 0.35, corresponding to the total binder used from 10% to 30%. The research findings could help engineers in optimizing the fly ash proportion and estimating the UCS of soil stabilization by cement and fly ash. Full article

(This article belongs to the Section Infrastructures Materials and Constructions)

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21 pages, 3971 KiB

Open AccessArticle

Freight Operations Modelling for Urban Delivery and Pickup with Flexible Routing: Cluster Transport Modelling Incorporating Discrete-Event Simulation and GIS

by Zichong Lyu, Dirk Pons, Yilei Zhang and Zuzhen Ji

Infrastructures 2021, 6(12), 180; https://doi.org/10.3390/infrastructures6120180 - 17 Dec 2021

Cited by 9 | Viewed by 4184

Abstract

Urban pickup and delivery (PUD) activities are important for logistics operations. Real operations for general freight involve a high degree of complexity due to daily variability. Discrete-event simulation (DES) is a method that can mimic real operations and include stochastic parameters. However, realistic [...] Read more.

Urban pickup and delivery (PUD) activities are important for logistics operations. Real operations for general freight involve a high degree of complexity due to daily variability. Discrete-event simulation (DES) is a method that can mimic real operations and include stochastic parameters. However, realistic vehicle routing is difficult to build in DES models. The objective is to create a DES model for realistic freight routing, which considers the driver’s routing decisions. Realistic models need to predict the delivery route (including time and distance) for variable consignment address and backhaul pickup. Geographic information systems (GIS) and DES were combined to develop freight PUD models. GIS was used to process geographical data. Two DES models were developed and compared. The first was a simple suburb model, and the second an intersection-based model. Real industrial data were applied including one-year consignment data and global positioning system (GPS) data. A case study of one delivery tour is shown, with results validated with actual GPS data. The DES results were also compared with conventional GIS models. The result shows the intersection-based model is adequate to mimic actual PUD routing. This work provides a method for combining GIS and DES to build freight operation models for urban PUD. This has the potential to help industry logistics practitioners better understand their current operations and experiment with different scenarios. Full article

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16 pages, 1421 KiB

Open AccessArticle

A Systematic Review of Permeable Pavements and Their Unbound Material Properties in Comparison to Traditional Subbase Materials

by Dansani Vasanthan Muttuvelu and Erik Kjems

Infrastructures 2021, 6(12), 179; https://doi.org/10.3390/infrastructures6120179 - 16 Dec 2021

Cited by 7 | Viewed by 5270

Abstract

This paper is a literature review focused on permeable pavements and especially the permeable subbase material. Run-off water from the surface is traditionally let through a drainage system, and the roads are kept dry. Due to climate changes, heavy precipitation and high-intensity rainfalls [...] Read more.

This paper is a literature review focused on permeable pavements and especially the permeable subbase material. Run-off water from the surface is traditionally let through a drainage system, and the roads are kept dry. Due to climate changes, heavy precipitation and high-intensity rainfalls are putting pressure on the infrastructure. Traditionally, water in subbase materials reduces the resilient E-moduli and the lifespan of the pavement design. Studies show that increasing saturation reduces the bearing capacity of a traditional subbase material. Unbound materials with highly grained fines and high moisture content have higher tendency to show reduced resilient E-moduli. One study was found where the E-moduli of five different coarse grained aggregates used in permeable pavements were examined through a triaxial test. It was found that the E-moduli varied from 110–371 MPa. Other studies examining the E-moduli of permeable subbases based on moisture content were not found. However, this paper discusses different experiences regarding the bearing capacity of traditional vs. permeable subbase materials. It also covers a discussion and an analysis of missing research areas that needs to be investigated for further knowledge about the usage of permeable pavements in areas with a risk of flooding. Full article

(This article belongs to the Special Issue Pavement Sustainability)

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14 pages, 5794 KiB

Open AccessArticle

Static and Impact Response of a Single-Span Stone Masonry Arch

by Bora Pulatsu, Semih Gonen and Paulo B. Lourenço

Infrastructures 2021, 6(12), 178; https://doi.org/10.3390/infrastructures6120178 - 16 Dec 2021

Cited by 6 | Viewed by 2702

Abstract

Unreinforced masonry structures are susceptible to man-made hazards such as impact and blast loading. However, the literature on this subject mainly focuses on masonry wall behavior, and there is a knowledge gap about the behavior of masonry arches under high-strain loading. In this [...] Read more.

Unreinforced masonry structures are susceptible to man-made hazards such as impact and blast loading. However, the literature on this subject mainly focuses on masonry wall behavior, and there is a knowledge gap about the behavior of masonry arches under high-strain loading. In this context, this research aims to investigate both quasistatic and impact response of a dry-joint stone masonry arch using the discrete element method. Rigid blocks with noncohesive joint models are adopted to simulate dry-joint assemblages. First, the employed modeling strategy is validated utilizing the available experimental findings, and then sensitivity analyses are performed for both static and impact loading, considering the effect of joint friction angle, contact stiffness, and damping parameters. The outcomes of this research strengthen the existing knowledge in the literature regarding the computational modeling of masonry structures that are subjected to usual and extreme loading conditions. The results highlight that applied discontinuum-based numerical models are more sensitive to stiffness parameters in high-strain loading than static analysis. Full article

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19 pages, 1286 KiB

Open AccessReview

Advancing Resilience of Critical Health Infrastructures to Cascading Impacts of Water Supply Outages—Insights from a Systematic Literature Review

by Nathalie Sänger, Christine Heinzel and Simone Sandholz

Infrastructures 2021, 6(12), 177; https://doi.org/10.3390/infrastructures6120177 - 14 Dec 2021

Cited by 8 | Viewed by 5289

Abstract

The current understanding of critical health infrastructure resilience is still dominated by a technical perspective. Reality however is different, as past events including the COVID-19 pandemic have revealed: emergency situations are only rarely exclusively technical in nature. Instead they are a product of [...] Read more.

The current understanding of critical health infrastructure resilience is still dominated by a technical perspective. Reality however is different, as past events including the COVID-19 pandemic have revealed: emergency situations are only rarely exclusively technical in nature. Instead they are a product of prior circumstances, often linked to natural hazards, technical mishaps, and insufficient social and organizational preparedness structures. However, experiences and lessons learned from past events are still largely overlooked and have not sufficiently found their way into conceptual understandings of critical health infrastructure resilience. This paper addresses this gap by challenging the one-sided and technically oriented understanding of resilience in the context of critical health infrastructure. Based on a systematic literature review, it assesses real-world cases of water supply failures in healthcare facilities, a serious threat largely overlooked in research and policy. The results underscore the need for targeted organizational strategies to deal with cascading impacts. The overall findings show that addressing technical aspects alone is not sufficient to increase the overall resilience of healthcare facilities. Broadening the dominant resilience understanding is hence an important foundation for healthcare infrastructures to improve risk management and emergency preparedness strategies to increase their resilience towards future disruptions. Full article

(This article belongs to the Special Issue Infrastructure Resilience in Emergency Situations)

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18 pages, 3618 KiB

Open AccessReview

Application of Digital Image Correlation in Structural Health Monitoring of Bridge Infrastructures: A Review

by Mohammed Abbas Mousa, Mustafasanie M. Yussof, Ufuoma Joseph Udi, Fadzli Mohamed Nazri, Mohd Khairul Kamarudin, Gerard A. R. Parke, Lateef N. Assi and Seyed Ali Ghahari

Infrastructures 2021, 6(12), 176; https://doi.org/10.3390/infrastructures6120176 - 13 Dec 2021

Cited by 52 | Viewed by 6457

Abstract

A vision-based approach has been employed in Structural Health Monitoring (SHM) of bridge infrastructure. The approach has many advantages: non-contact, non-destructive, long-distance, high precision, immunity from electromagnetic interference, and multiple-target monitoring. This review aims to summarise the vision- and Digital Image Correlation (DIC)-based [...] Read more.

A vision-based approach has been employed in Structural Health Monitoring (SHM) of bridge infrastructure. The approach has many advantages: non-contact, non-destructive, long-distance, high precision, immunity from electromagnetic interference, and multiple-target monitoring. This review aims to summarise the vision- and Digital Image Correlation (DIC)-based SHM methods for bridge infrastructure because of their strategic significance and security concerns. Four different bridge types were studied: concrete, suspension, masonry, and steel bridge. DIC applications in SHM have recently garnered attention in aiding to assess the bridges’ structural response mechanisms under loading. Different non-destructive diagnostics methods for SHM in civil infrastructure have been used; however, vision-based techniques like DIC were only developed over the last two decades, intending to facilitate damage detection in bridge systems with prompt and accurate data for efficient and sustainable operation of the bridge structure throughout its service life. Research works reviewed in this article demonstrated the DIC capability to detect damage such as cracks, spalling, and structural parameters such as deformation, strains, vibration, deflection, and rotation. In addition, the reviewed works indicated that the DIC as an efficient and reliable technique could provide sustainable monitoring solutions for different bridge infrastructures. Full article

(This article belongs to the Special Issue Resilient and Smart Transport Infrastructure for Connected and Autonomous Vehicles)

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14 pages, 2111 KiB

Open AccessArticle

Analysis of Pedestrians’ Perceptions about the Design Aspects of Crossing Facilities: A Case in Nizwa, Oman

by Muhammad Ashraf Javid, Mashood Khalid, Nazam Ali, Tiziana Campisi, Antonino Canale and Suniti Suparp

Infrastructures 2021, 6(12), 175; https://doi.org/10.3390/infrastructures6120175 - 9 Dec 2021

Cited by 3 | Viewed by 3296

Abstract

This study aims to identify the key factors in pedestrians’ intentions when using crossing facilities. For this purpose, a comprehensive questionnaire was designed and conducted at selected locations in Nizwa city. The main investigated variables are linked to personal characteristics, opinions on the [...] Read more.

This study aims to identify the key factors in pedestrians’ intentions when using crossing facilities. For this purpose, a comprehensive questionnaire was designed and conducted at selected locations in Nizwa city. The main investigated variables are linked to personal characteristics, opinions on the main reasons for accidents, and how hard it is for pedestrians to cross roads at different locations in Nizwa city. Statements were also designed on the safety and health aspects of pedestrian crossings, as well as the physical and design aspects of pedestrian crossing facilities. Suitable locations were selected for the survey to assess the main concerns of pedestrian facilities. A total of 280 usable samples were collected from the selected locations. The analysis results revealed that young pedestrians do not find it difficult to use pedestrian bridges and underpasses when crossing roads. Pedestrians’ prioritization of safety when crossing, pedestrians’ health conditions, the proper cleaning and lighting of facilities, and the good design of facilities are significant determinants of pedestrians’ intentions when using crossing facilities. Crossing facilities need to be maintained properly, for example, through the cleaning and lighting of facilities. Proper awareness among pedestrians and vehicle drivers is required for the safety of pedestrians. Full article

(This article belongs to the Special Issue Road and Rail Infrastructures)

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16 pages, 1991 KiB

Open AccessArticle

Resilience of Railway Transport to Four Types of Natural Hazards: An Analysis of Daily Train Volumes

by Vigile Marie Fabella and Sonja Szymczak

Infrastructures 2021, 6(12), 174; https://doi.org/10.3390/infrastructures6120174 - 8 Dec 2021

Cited by 11 | Viewed by 4061

Abstract

A crucial step in measuring the resilience of railway infrastructure is to quantify the extent of its vulnerability to natural hazards. In this paper, we analyze the vulnerability of the German railway network to four types of natural hazards that regularly cause disruptions [...] Read more.

A crucial step in measuring the resilience of railway infrastructure is to quantify the extent of its vulnerability to natural hazards. In this paper, we analyze the vulnerability of the German railway network to four types of natural hazards that regularly cause disruptions in German rail operations: floods, mass movements, slope fires, and tree falls. Using daily train traffic data matched with various data on disruptive events, we quantify the extent to which these four types of natural hazard reduce daily train traffic volumes. With a negative binomial count data regression, we find evidence that the track segments of the German railway network are most vulnerable to floods, followed by mass movements and tree-fall events. On average, floods reduce traffic on track segments by 19% of the average daily train traffic, mass movements by 16%, and tree fall by 4%. Moreover, when more than one type of natural hazard affects the track segment on the same day, train traffic on that segment falls by 34% of the average train traffic. Slope fires have an ambiguous and nonrobust effect on train traffic due to the reverse causality due to its triggering factors. This is the first study that attempts to rank different natural hazards according to their impact on railway traffic. The results have implications for the selection of resilience strategy and can help prioritize policy measures. Full article

(This article belongs to the Special Issue Resilience of Infrastructures to Natural Hazards)

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18 pages, 4671 KiB

Open AccessArticle

Structural Performance Assessment of Airfield Concrete Pavements Based on Field and Laboratory Data

by Konstantinos Gkyrtis, Angeliki Armeni, Christina Plati and Andreas Loizos

Infrastructures 2021, 6(12), 173; https://doi.org/10.3390/infrastructures6120173 - 8 Dec 2021

Cited by 5 | Viewed by 3549

Abstract

Maintenance interventions and rehabilitation actions in airfield pavements are time-consuming and adversely affect pavements’ serviceability (i.e., airport closures), with a profound impact on the airport economics. Once a pavement is constructed, a robust asset management prerequisites systematic and accurate knowledge of pavement condition [...] Read more.

Maintenance interventions and rehabilitation actions in airfield pavements are time-consuming and adversely affect pavements’ serviceability (i.e., airport closures), with a profound impact on the airport economics. Once a pavement is constructed, a robust asset management prerequisites systematic and accurate knowledge of pavement condition throughout its service life. Evaluating a pavement’s structural capacity in the field involves the integration of multiple Non-Destructive Testing (NDT) systems, with the Falling Weight Deflectometer (FWD) being the most indicative NDT system for pavement evaluation. The purpose of the present study is to develop a methodology for the assessment of airfield concrete pavements. A new and non-trafficked Jointed Plain Concrete Pavement (JPCP), facing early-life cracks shortly after a runway’s expansion activities, was utilized for the investigation. Multiple types of data collected in the field, including deflections, load transfer efficiency at joints and cracks, concrete thickness through coring as well as data retrieved in the laboratory (concrete’s flexural strength), helped to define the pavement’s performance and assess its damage potential. Overall, the integration of such data can provide the related airport authorities the necessary information in order to make a rational asset management and enhance the efficiency of airfield infrastructures. The methodology is applicable for both new and in-service pavements. Full article

(This article belongs to the Special Issue Research and Developments in Pavements)

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20 pages, 4303 KiB

Open AccessArticle

Seismic Behavior of a Class of Mixed Reinforced Concrete-Steel Buildings Subjected to Near-Fault Motions

by Paraskevi K. Askouni and George A. Papagiannopoulos

Infrastructures 2021, 6(12), 172; https://doi.org/10.3390/infrastructures6120172 - 5 Dec 2021

Cited by 7 | Viewed by 3191

Abstract

This paper investigates the seismic behavior of a class of mixed reinforced concrete-steel buildings. In particular, mixed buildings constructed by r/c (reinforced concrete) at their lower story(ies) and structural steel at their upper story(ies) are studied from the viewpoint of their wide application [...] Read more.

This paper investigates the seismic behavior of a class of mixed reinforced concrete-steel buildings. In particular, mixed buildings constructed by r/c (reinforced concrete) at their lower story(ies) and structural steel at their upper story(ies) are studied from the viewpoint of their wide application in engineering praxis. The need to investigate the seismic behavior for this type of mixed buildings arises from the fact that the existent literature is small and that modern seismic codes do not offer specific seismic design recommendations for them. To study the seismic behavior of mixed r/c-steel buildings, a 3-D numerical model is employed and five realistic r/c-steel mixed buildings are simulated. Two cases of the support condition, i.e., fixed or pinned, of the lowest steel story to the upper r/c one are examined. The r/c and steel parts of the mixed buildings are initially designed as separate structures by making use of the relevant seismic design guidelines of Eurocode 8, and then the seismic response of these buildings is computed through non-linear time-history analyses. The special category of near-fault seismic motions is selected in these time-history analyses to force the mixed r/c-steel buildings under study to exhibit a strong non-linear response. Seismic response indices in terms of inter-story drift ratio, residual inter-story drift ratio and peak floor absolute accelerations are computed. The maximum values of these indices are discussed by comparing the two aforementioned kinds of support conditions and checking the satisfaction of specific seismic performance limits. Conclusions regarding the expected seismic behavior of mixed r/c-steel buildings under near-fault seismic motions are drawn. Finally, the need to introduce specific design recommendations for mixed r/c-steel buildings in modern seismic codes is stressed. Full article

(This article belongs to the Special Issue Advances in Structural Dynamics and Earthquake Engineering)

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16 pages, 5151 KiB

Open AccessArticle

On the Effectiveness of Vibration-Based Monitoring for Integrity Management of Prestressed Structures

by Marco Andrea Pisani, Maria Pina Limongelli, Pier Francesco Giordano and Mattia Palermo

Infrastructures 2021, 6(12), 171; https://doi.org/10.3390/infrastructures6120171 - 3 Dec 2021

Cited by 9 | Viewed by 3565

Abstract

In this paper, the effectiveness of vibration-based tests for the detection of damages for prestressed concrete beams is investigated. Despite large research efforts, discrepant and sometimes contradicting conclusions have been drawn regarding the efficacy and reliability of vibration-based monitoring for prestressed structures. Herein, [...] Read more.

In this paper, the effectiveness of vibration-based tests for the detection of damages for prestressed concrete beams is investigated. Despite large research efforts, discrepant and sometimes contradicting conclusions have been drawn regarding the efficacy and reliability of vibration-based monitoring for prestressed structures. Herein, a contribution to this discussion is provided by tackling the problem from a different perspective. Specifically, the question that this paper intends to answer is: “Do vibration-based tests support decision-makers in integrity management operations for prestressed elements?” The discussion is carried out by comparing the performance of prestressed and ordinary reinforced concrete beams with similar capacities. Both analytical and numerical case studies are considered. Results show that, for prestressed beams, in contrast to reinforced concrete beams, modal parameters can provide information regarding damage only when the structure is close to its ultimate conditions. This makes this information hardly useful for integrity management purposes and the effectiveness of vibration-based tests questionable for this type of structural element. Full article

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13 pages, 2278 KiB

Open AccessArticle

A Hybrid Surrogate Model for the Prediction of Solitary Wave Forces on the Coastal Bridge Decks

by Jinsheng Wang, Shihao Xue and Guoji Xu

Infrastructures 2021, 6(12), 170; https://doi.org/10.3390/infrastructures6120170 - 1 Dec 2021

Cited by 15 | Viewed by 2661

Abstract

To facilitate the establishment of the probabilistic model for quantifying the vulnerability of coastal bridges to natural hazards and support the associated risk assessment and mitigation activities, it is imperative to develop an accurate and efficient method for wave forces prediction. With the [...] Read more.

To facilitate the establishment of the probabilistic model for quantifying the vulnerability of coastal bridges to natural hazards and support the associated risk assessment and mitigation activities, it is imperative to develop an accurate and efficient method for wave forces prediction. With the fast development of computer science, surrogate modeling techniques have been commonly used as an effective alternative to computational fluid dynamics for the establishment of a predictive model in coastal engineering. In this paper, a hybrid surrogate model is proposed for the efficient and accurate prediction of the solitary wave forces acting on coastal bridge decks. The underlying idea of the proposed method is to enhance the prediction capability of the constructed model by introducing an additional surrogate to correct the errors made by the main predictor. Specifically, the regression-type polynomial chaos expansion (PCE) is employed as the main predictor to capture the global feature of the computational model, whereas the interpolation-type Kriging is adopted to learn the local variations of the prediction error from the PCE. An engineering case is employed to validate the effectiveness of the hybrid model, and it is observed that the prediction performance (in terms of residual mean square error and correlation coefficient) of the hybrid model is superior to the optimal PCE and artificial neural network (ANN) for both horizontal and vertical wave forces, albeit the maximum PCE degrees used in the hybrid model are lower than the optimal degrees identified in the pure PCE model. Moreover, the proposed hybrid model also enables the extraction of explicit predictive equations for the parameters of interest. It is expected that the hybrid model could be extended to more complex wave conditions and structural shapes to facilitate the life-cycle structural design and analysis of coastal bridges. Full article

(This article belongs to the Special Issue Reliability-Based Service-Life Assessment of Aging Bridges)

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15 pages, 2139 KiB

Open AccessArticle

Public Bus Transportation System Environmental Impact Projections Regarding Different Policy Scenarios—A LCA Study

by Michelle Leichter, Isadora Hackenhaar and Ana Passuello

Infrastructures 2021, 6(12), 169; https://doi.org/10.3390/infrastructures6120169 - 1 Dec 2021

Cited by 4 | Viewed by 4189

Abstract

Urban activities, such as transportation, are responsible for a large portion of energy-related CO₂ emissions. As the need for sustainable urban development increases, decision-makers embrace Life Cycle Assessment (LCA) as a reliable tool capable of generating scientifically based information on environmental impacts. [...] Read more.

Urban activities, such as transportation, are responsible for a large portion of energy-related CO₂ emissions. As the need for sustainable urban development increases, decision-makers embrace Life Cycle Assessment (LCA) as a reliable tool capable of generating scientifically based information on environmental impacts. However, there is still a lack of an analysis standard regarding the particularities of urban systems. Therefore, this research aims to define current and future environmental profiles, considering a case study of the public transport system in Porto Alegre, considering specificities of the urban context and different public policy scenarios through LCA. These results show that, although the transportation system management relies on the municipalities, the higher significance of environmental impacts depend on a national policy for using biodiesel in the diesel sold, which could lead to an increase of, for example, up to 9.4% of CO₂ emissions from 2017 (baseline) to 2030. Finally, it is perceivable that to conduct a LCA to support decision-making in public urban services, a detailed approach is needed considering that technological variables interact with the territorial context and policy changes. Full article

(This article belongs to the Special Issue Smart, Sustainable and Resilient Infrastructures)

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14 pages, 3862 KiB

Open AccessArticle

Effects of Axial Relative Ground Movement on Small Diameter Polyethylene Piping in Loose Sand

by Auchib Reza and Ashutosh Sutra Dhar

Infrastructures 2021, 6(12), 168; https://doi.org/10.3390/infrastructures6120168 - 1 Dec 2021

Cited by 2 | Viewed by 2940

Abstract

Small diameter (42 mm) medium density polyethylene (MDPE) pipes are widely used in the gas distribution system in Canada and other countries. They are sometimes exposed to ground movements resulting from landslides or earthquakes. The current design guidelines for evaluating the pipes subjected [...] Read more.

Small diameter (42 mm) medium density polyethylene (MDPE) pipes are widely used in the gas distribution system in Canada and other countries. They are sometimes exposed to ground movements resulting from landslides or earthquakes. The current design guidelines for evaluating the pipes subjected to ground movement were developed for steel pipes of larger diameters and may not apply to flexible MDPE pipes. This paper evaluates 42 mm diameter MDPE pipes buried in loose sand under axial relative ground movement for developing a design method for the pipes. MDPE is a viscoelastic material; therefore, the behaviour of MDPE pipes exposed to landslides would depend on the rate of ground movements. In this research, full-scale laboratory tests were conducted to investigate the responses of buried pipes under various rates of relative axial displacement. Finite element modelling of the tests was used to interpret the observed behaviour using the continuum mechanics framework. The study revealed that the pulling force on the pipe depends on the rate of relative ground displacement (pulling rate). The nondimensional pulling force possessed a nonlinear relationship with the pulling rate. A rate-dependent interface friction angle could be used to calculate the maximum pulling forces using the conventional design guidelines for the pipes in loose sand. Based on the pulling force, the pipe wall strains can be estimated using the methods available for larger diameter pipes. Full article

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18 pages, 1178 KiB

Open AccessArticle

Resilience Endangered: The Role of Regional Airports in Remote Areas in Sweden

by Christine Große, Pär M. Olausson and Bo Svensson

Infrastructures 2021, 6(12), 167; https://doi.org/10.3390/infrastructures6120167 - 26 Nov 2021

Cited by 5 | Viewed by 3226

Abstract

This paper examines the role of regional airports in regional and municipal crisis preparedness based on evidence from a case study in Sweden. During the summer of 2018, Sweden experienced some of the most extensive wildfires in modern time. Aerial suppression, for which [...] Read more.

This paper examines the role of regional airports in regional and municipal crisis preparedness based on evidence from a case study in Sweden. During the summer of 2018, Sweden experienced some of the most extensive wildfires in modern time. Aerial suppression, for which airports provided the essential preconditions, played an important role in extinguishing these fires. This study includes analyses of public policies that shape the Swedish airport system as well as evidence from interviews and a workshop with stakeholders. The results show that an efficiently operated network of regional airports is critical not only for crisis management but also to ensure important societal services such as health care in sparsely inhabited regions. Moreover, access to quick transportation by air is necessary for the Swedish Prison and Probation Service, tourism industry, public institutions and private businesses. Additionally intensified by effects of both the public debate on flight shame and the COVID-19 pandemic on air-based transportation, the insights arising from this study emphasise that the currently one-sided focus on the number of passengers is an insufficient foundation for the Swedish airport system to construct a resilient base for regional development, crisis management and civil defense. Full article

(This article belongs to the Special Issue Infrastructure Resilience in Emergency Situations)

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15 pages, 8862 KiB

Open AccessArticle

Strength Enhancement of Interlocking Hollow Brick Masonry Walls with Low-Cost Mortar and Wire Mesh

by Panuwat Joyklad, Nazam Ali, Muhammad Usman Rashid, Qudeer Hussain, Hassan M. Magbool, Amr Elnemr and Krisada Chaiyasarn

Infrastructures 2021, 6(12), 166; https://doi.org/10.3390/infrastructures6120166 - 24 Nov 2021

Cited by 2 | Viewed by 3644

Abstract

Cement–clay Interlocking Hollow Brick Masonry (CCIHBM) walls are characterized by poor mechanical properties of bricks and mortar. Their performance is observed to be unsatisfactory under both gravity and seismic loads. There is an urgent need to develop sustainable, environmentally friendly, and low-cost strengthening [...] Read more.

Cement–clay Interlocking Hollow Brick Masonry (CCIHBM) walls are characterized by poor mechanical properties of bricks and mortar. Their performance is observed to be unsatisfactory under both gravity and seismic loads. There is an urgent need to develop sustainable, environmentally friendly, and low-cost strengthening materials to alter the structural behaviour of brick masonry walls in terms of strength and ductility. The results of an experimental investigation conducted on the diagonal compressive response of CCIHBM walls are presented in this study. In this experimental study, a total of six CCIHBM walls were constructed using cement–clay interlocking hollow bricks. One was tested as a control or reference wall, whereas the remaining walls were strengthened using cement mortar. In some walls, the cement mortar was also combined with the wire mesh. The research parameters included the type of Ordinary Portland Cement (OPC) (Type 1 and Type 2), thickness of cement mortar (10 mm and 20 mm), and layers of wire mesh (one and three layers). The experimental results indicate that control or unstrengthened CCIHBM walls failed in a very brittle manner at a very low ultimate load and deformation. The control CCIHBM wall, i.e., W-CON, failed at an ultimate load of 247 kN, and corresponding deflection was 1.8 mm. The strength and ductility of cement mortar and wire mesh-strengthened walls were found to be higher than the reference CCIHBM wall. For example, the ultimate load and deformation of cement-mortar-strengthened wall were found to be 143% and 233% higher than the control wall, respectively. Additionally, the ultimate failure modes of cement mortar and wire mesh strengthened were observed as ductile as compared to the brittle failure of reference wall or unstrengthened CCIHBM wall, which increased by 66% and 150% as compared with the control wall. Full article

(This article belongs to the Special Issue Sustainability of Building Materials and Structures)

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Infrastructures, Volume 6, Issue 12 (December 2021) – 18 articles

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