Infrastructures, Volume 3, Issue 3 (September 2018) – 24 articles

In densely populated settings like Chittagong, Bangladesh cities facing rapid urbanization and economic growth are challenged to provide open space for its citizens. For example, the population of this port city is 14,200 people per square kilometer and there is a struggle to provide open space. Again, the planning proposal did not set any open space standard to achieve its open space aspirations Hence, the objectives of this paper are four-fold: (i) Develop an understanding of open space standards to establish relative benchmarks for potential use in Chittagong. (ii) Examine existing formal open space in Chittagong. (iii) Document the existing informal open space areas in Chittagong according to the planning direction. (iv) Recommend an approach that can be used to realize open spaces in Chittagong. To achieve these, this paper documents the existing open space scenario in the city, examines the recommended open space standards developed by organizations such as the World Health Organization (WHO) and the Dhaka Structural Plan (2016–2035) (the planning document of the capital city of Bangladesh) to identify to what extent these ‘benchmark’ standards are appropriate for use in the city. A discussion on open space in Chittagong and the criteria used to ‘frame’ open space calculations in the city is then conducted to provide a foundation to reflect upon the world’s various open space recommendations. Ultimately, by analyzing existing open space recommendations and their associated well-being aspirations, the research suggests that a new standard relating to the unique characteristics of the city should be used when developing open space standards in Chittagong. Full article

This article presents a study on the structural behavior of the Government Building that is part of the old Lecumberri Palace and which currently houses the Mexican General Archive of the Nation. This building was inaugurated in 1900 and closed in 1976, after serving as a prison for 76 years. It was reopened in 1982 after it had undergone several remodeling works. The construction is made of brick masonry with lime mortar. It is supported by a deposit of overly compressible high-plasticity clays. The main problems of this building are the appearance of cracks in both interior and exterior walls, and moisture in the ground floor, caused by differential settlements. The study entailed a geometric and a damage survey as well as ambient vibration tests in order to determine the dynamic properties of the construction. The data obtained was used for the making of a model that, using the finite element method, was analyzed under different load conditions. This study has focused on the overall response with the assumption of smeared crack damage. According to the results, the building’s safety was deemed as acceptable. It has the capability to withstand seismic actions as established by the Mexican Building Code due to the high density of its walls and the resulting stiffness, which infer that the fundamental vibration period of the building would be distant from the predominant vibration period of the soil. This highlights the idea that the building’s critical condition is constituted by the differential settlements, which cause damage in the construction. Full article

Interventions in historic brick buildings require an exhaustive analysis of the current characteristics of bricks in order to establish the role performed by these elements in the buildings. This study presents the results of an experimental analysis of the compressive strength of brick specimens extracted from different buildings built in the 19th and 20th centuries in the province of Zamora (Spain). The study analyses specimens with very different characteristics to compare results from different masonry units and manufacturing processes. Specimens are classified into four groups according to their macroscopic and microscopic analyses. Compressive strength results are correlated to the above classification and to the results of density, absorption and open porosity of the samples. The compressive strength results present high variation between clay bricks (9.2–64.4 N/mm²) and between samples extracted from the same brick due to the heterogeneity of the material. Correlations between compressive strength and open porosity, absorption and dry density values are observed, with less dispersion in the case of high sintering level, up to 1000 °C. Finally, the compliance with the current Spanish Technical Building Code with respect to their compressive strength is checked. Full article

A study of moisture pathologies in a modern residential multifamily building is presented. The housing block was designed under the regulation NBE-CT of 1979 in northern Spain. After the appearance of some moisture problems in the façades, three complementary studies were conducted to analyze the situation of the envelope and diagnose the best improvement possibilities. First, indoor conditions of temperature and humidity of the apartments with moisture pathologies were monitored. During 40 winter days, the occupancy, heating operation, and natural ventilation were analyzed. Second, the inner and outer surface temperatures of the studied façades were measured. Thermal insulation degree, thermal capacity, and thermal bridge effects were measured to assess the risk of interstitial condensation under the real conditions of use. Third, an infrared thermographic survey was carried out, which allowed the detection of irregularities and the assessment of moisture problems. The wrong interpretations, which would have been made if the complementary studies had not been done, are exposed. The key towards the accurate diagnosis was the combination of tools. Finally, some technical solutions based on ventilation or thermal insulation enhancement are proposed as different ways to reduce the high levels of relative humidity indoors and minimize the risk of condensation in the future. Full article

One quarter of bridges in Canada and the United States need repair. The present study provides a critical overview of the state-of-the-art existing condition assessment techniques for reinforced concrete bridges, with an emphasis on current practice in North America. The techniques were classified into five categories, including visual inspection, load testing, non-destructive evaluation, structural health monitoring, and finite element modelling. The potential applications of these technologies are discussed and compared, highlighting their primary advantages and limitations. The review revealed that quantitative assessment could be effectively achieved using several complementary technologies. It is shown that there is need for concerted research efforts to achieve automated data collection and interpretation analyses. Also, the configuration of monitoring systems was found to be paramount in effectively assessing bridge performance parameters of interest. The study suggests appropriate investigation methods for some bridge deterioration mechanisms. Knowledge gaps and challenges in this field are outlined in order to motivate further research and development of these technologies. Full article

Health monitoring and prediction in different types of structures is essential in order to maintain optimal conditions. Some of the pathologies that affect their structural stability are characterized by distinct thermal properties compared to unaltered areas. Infrared thermography (IRT) is a technique based on the acquisition of the thermal radiation of the bodies using thermal sensors of infrared (IR) cameras, which produce an image of the thermal infrared radiation captured through the conversion of the radiation values to temperature values. Therefore, this technique can be used in different studies to analyse structures with one or more pathologies based on their anomalous thermal behaviour with regard to the unaltered surroundings. As a consequence, this review presents various IRT applications to infrastructure inspections, showing the utility of the technique. Full article

In order to fully perform their functions and be durable, mortars for renders and plasters are requested to have a set of characteristics that can vary with the type of exposure to external environmental actions and the type of substrate. Generally, they need moderate strength, high deformability, some water protection capability, good adhesion to the substrate and compatibility with the pre-existent materials. The presence of water and its movement inside the pore structure of the mortars are among the most significant causes of degradation. Moreover, several authors consider that the main factors for durability and good performance of lime-based mortars are mostly related with the good quality of the binder and the use of adequate aggregates. This paper intends to study the effect of ageing on the properties and durability of air lime mortars, using aggregates of different mineralogy. For this purpose, different mortars compositions are exposed to an accelerated weathering test under defined conditions. The obtained characteristics are discussed and compared with the results obtained with the same mortars tested in laboratory conditions. The effects of the aggregate type on the durability of mortars seem to be linked to their effects on the mortars porous structure. Full article

Extreme weather can cause severe damage and widespread power outages across utility service areas. The restoration process can be long and costly and emergency managers may have limited computational resources to optimize the restoration process. This study takes an agent based modeling (ABM) approach to optimize the utility storm recovery process in Connecticut. The ABM is able to replicate past storm recoveries and can test future case scenarios. We found that parameters such as the number of outages, repair time range and the number of utility crews working can substantially impact the estimated time to restoration (ETR). Other parameters such as crew starting locations and travel speeds had comparatively minor impacts on the ETR. The ABM can be used to train new emergency managers as well as test strategies for storm restoration optimization. Full article

For engineering systems, decision analysis can be used to determine the optimal decision from a set of options via utility maximization. Applied to inspection and maintenance planning, decision analysis can determine the best inspection and maintenance plan to follow. Decision analysis is relatively straightforward for simple systems. However, for more complex systems with many components or defects, the set of all possible inspection and maintenance plans can be very large. This paper presents the use of a genetic algorithm to perform inspection and maintenance plan optimization for complex systems. The performance of the genetic algorithm is compared to optimization by exhaustive search. A numerical example of life cycle maintenance planning for a corroding pressure vessel is used to illustrate the method. Genetic algorithms are found to be an effective approach to reduce the computational demand of solving complex inspection and maintenance optimizations. Full article

The determination of the optimal interventions to execute on rail infrastructure networks is a challenging task, due to the many types of objects (e.g., bridges, tracks, and switches), how the objects work together to provide service, and the possible reductions in costs and service disruptions as obtained by grouping interventions. Although railway infrastructure managers are using computer systems to help them determine intervention programs, there are none that result in the highest net benefits while taking into consideration all of these aspects. This paper presents a network flow model approach that allows for determining the optimal intervention programs for railway infrastructure networks while taking into considerations different types of objects, how the objects work together to provide service, and object and object-traffic dependencies. The network flow models are formulated as mixed integer linear programs, where the optimal intervention program is found by using the simplex and branch and bound algorithms. The modelling approach is illustrated by using it to determine the optimal intervention program for a 2200 m multi-track railway line consisting of 11 track sections, 23 switches, and 39 bridges. It is shown that the proposed constrained network flow model can be used to determine the optimal intervention program within a reasonable amount of time, when compared to more traditional models and search algorithms. Full article

Resilience research includes multiple definitions, concepts, perspectives, and applications across a broad range of academic disciplines. While experts, policy-makers, and practitioners assert that resilience requires holism, what is considered holistic is rarely discussed. The traditional scientific approach to holism is to engage multiple disciplines. However, this review studies an alternative approach to holism that engages multiple perspectives, as suggested by integral theory. An integral approach requires consideration of at least four irreducible domains: (1) subjective experience, (2) intersubjective culture, (3) objective behavior, and (4) interobjective systems. This way of approaching holism both engages multiple disciplines and reveals important gaps in the popular understanding of resilient infrastructure. For example, organizing the 20 most highly cited resilience research articles from all disciplines according to the Integral Map reveals that most articles in the sample set are distributed among three of the four perspectives corresponding to experience, behavior, and systems. None of the most popular articles studies resilience through the lens of culture. Thus, the importance of factors such as organizational values and group intentionality may be underappreciated in the scholarly literature. Full article

Detection of early-stage corrosion on slender steel members is crucial for preventing buckling failures of steel structures. An active photoacoustic fiber optic sensor (FOS) system is reported herein for the early-stage steel corrosion detection of steel plates and rebars using surface ultrasonic waves. The objective of this study is to investigate a potential method for detecting surface corrosion/rust of steel rods using numerically simulated surface ultrasonic waves. The finite element method (FEM) was applied in the simulation of propagating ultrasonic waves on steel rod models. The pitch-catch mode of damage detection was adopted, in which one source (transmitter) and one sensor (receiver) were considered. In this research, radial displacements at the receiver were simulated and analyzed by short-time Fourier transform (STFT) for detecting, locating, and quantifying surface rust located between the transmitter and the receiver. From our time domain and frequency domain analyses, it was found that the presence, location, and dimensions (length, width, and depth) of surface rust can be estimated by ultrasonic wave propagation. Full article

In the past decade, Johannesburg has actively participated in the investment and development of the Gautrain and Rea Vaya public transportation modes. However, the state of route networks connectedness amongst the two public transport modes has not been well documented. Thus, this study aimed to delineate the extent of routes network integration among the two modes. The study adopted a phenomenological case study survey design which applied a mixed-method approach to gather spatial, qualitative and quantitative data. Crowd sourced datasets from Facebook and Twitter were collected, and analyzed using the kriging interpolation method and descriptive statistics. Key informant interviews were also used to unpack the status quo of the two modes. Results indicate that there are limited areas where the route networks between the two modes are currently integrated. Variations in income levels may be a factor currently preventing inter-transfer between the two modes. The Rea Vaya has proven successful in improving accessibility to economic opportunities, with 70% of the social media posts reflecting positive views regarding route and travel timetables. The study recommends conscious efforts in planning and developing integrated rail and road route networks to promote efficiency of public transport systems. Full article

To limit additional (net) land take for economic activities, the reality of space use needs to be properly understood. This was assessed by comparing the spatial patterns obtained from a field inventory with those from existing data for five case areas in Flanders (Belgium). Each case area is a transect from a high-density urban area to a suburban neighborhood or even a semi-rural zone. The statistics on these areas, based on official data, mostly derived from tax returns, social security contributions, and on commercial retail data, were checked with field observations. The location of economic activities and the patterns of space use vary in different settlement environments, resulting in the identification of typical characteristics for eight location environment types. While in, for example, core shopping centers a strong convergence can be noticed between existing statistics and the field inventory (71% of companies and 93% of parcels are detected on the field), in residential areas (21% of companies and 17% of parcels are detected on the field) the convergence is very limited. In other words, in some environments, (the combination of) data and statistics give a good understanding of the space use while, in other environments, gaps with realities in the field are obvious. Therefore, a field inventory system can enrich the picture and present another reality to complement both existing statistics and other land-use data methods such as remote sensing and web data extraction. Full article

Progressive collapse, the extensive or complete collapse of a structure resulting from the failure of one or a small number of structural components, has become a focus of research efforts and design considerations following events occurring at the Ronan Point apartment building in London, the Murrah Federal Building in Oklahoma City, and the World Trade Center in New York City. A principle research and design area for progressive collapse investigates the behavior of structural frames when column support is removed. The mechanism that results from loss of column support in structural frames characteristically involves beams that are unable to provide sufficient flexural resistance. Cable retrofit is one method to enhance existing frames and supplement or replace the post-mechanism beam load resistance with straight-legged catenary resistance after a column removal. The cables are located linearly along the beam geometry and are affixed at beam supports. This paper investigates both static and dynamic behavior of the catenary action of retrofit cables, which include both the linear and nonlinear material behavior of the cable material. Moreover, a simplified model serves as the basis for retrofit cable design is presented. Finite element modeling and experimentation in this paper verify and validate the applicability of the model. Finally, a framework for developing a procedure for retrofit cable design is presented. Full article

In the global airline industry, an airline’s fleet routing affects its profitability, level of service and its competitive position. Using a qualitative research approach, this paper examines Singapore Airlines Airbus A350-900XWB fleet deployment and route network development for the period 2016 to 2018. The qualitative data was examined using document analysis. The study found that Singapore Airlines has deployed the Airbus A350-900XWB aircraft on new air routes from Singapore to Cape Town via Johannesburg, Düsseldorf and Stockholm via Moscow and return. The Airbus A350-900XWB aircraft are also replacing older, less efficient aircraft as part of the company’s fleet modernization strategy. Singapore Airlines is also acquiring the new ultra-long-range variant of the Airbus A350-900XWB for use on its proposed new non-stop services from Singapore to Los Angeles and Newark Liberty Airport in New Jersey, USA. The longest flight stage length is the Singapore to San Francisco route which is 7339 nautical miles (13,594 km) in length. The shortest stage length is between Singapore and Kuala Lumpur (160 nautical miles or 297 km). The new non-stop services from Singapore to Los Angeles and New York City will be the longest non-stop services operated by Singapore Airlines. The flight stage lengths between Singapore and Los Angeles and Singapore and Newark Liberty Airport are 7621 nautical miles (14,114 km) and 8285 nautical miles (15,344 km), respectively. The greatest number of available seat kilometers (ASKs) are generated on Singapore Airlines Airbus A350-900 XWB service from Singapore to San Francisco (3.57 million ASKs). The smallest number of ASKs produced are on the short-haul service from Singapore to Kuala Lumpur (75,141 ASKs). Full article

Railway industry plays a critical role in transportation and transit systems attributed to the ever-growing demand for catering to both freight and passengers. However, owing to many challenges faced by railway stations such as harsh environments, traffic flow, safety and security risks, new and adaptive systems employing new technology are recommended. In this review, several wireless sensor networks (WSNs) applications are proposed for use in railway station systems, including advanced WSNs, which will enhance security, safety, and decision-making processes to achieve more cost-effective management in railway stations, as well as the development of integrated systems. The size, efficiency, and cost of WSNs are influential factors that attract the railway industry to adopt these devices. This paper presents a review of WSNs that have been designed for uses in monitoring and securing railway stations. This article will first briefly focus on the presence of different WSN applications in diverse applications. In addition, it is important to note that exploitation of the state-of-the-art tools and techniques such as WSNs to gain an enormous amount of data from a railway station is a new and novel concept requiring the development of artificial intelligence methods, such machine learning, which will be vital for the future of the railway industry. Full article

Population growth in cities and expanding city territory as well as population decline in rural areas pose a challenge for the existing transport network. Consequently, we observe a rapid change in transport infrastructure and transportation technology within the last few years. Due to novelty or differentness, it will initially be challenging to integrate them into the existing network in Western European cities and to identify suitable corridors leading to especially beneficial effects on the overall transport network. The effects of new technologies and (high-performance) infrastructures are hardly examined. It remains unclear how these novel transportation technologies will change society, our understanding of spatial proximity, mobility, and consequently the logistics sector. In this work, we give an overview regarding first considerations and reflections on the impacts of the changes and developments in the field of freight transportation. Our work mainly focusses on the estimation of the impacts of high-performance transport technologies on the society, spatial proximity, and the logistics sector while extending the European transportation network accordingly. In our understanding, we refer to high-performance transportation technologies as mobility systems with either high throughput (fast and/or high utilization loads) or very flexible application. To be more specific, we focus on Hyperloop technologies, Cargo-Sous-Terrain, freight airships, and drones. Full article

The present study mainly investigates the synthesis of calcined marl-based geopolymeric cement under different synthesis conditions including NaOH concentration, sodium silicate (SS)/sodium hydroxide (SH) mass ratios, solid (S)/liquid (L) mass ratios, calcination temperatures, curing temperatures, curing times, and aging intervals. The studied head sample was obtained from the Abu-Tartur phosphate mine in the Western Desert of Egypt and subjected to chemical and mineralogical characterizations using X-ray fluorescence (XRF), X-ray diffraction (XRD), and Fourier transform–infrared spectroscopy (FT–IR). Regarding calcination, this was conducted at 550, 650, 750, and 850 °C for one hour and resulted in thermal decomposition of calcite and saponite and the formation of new mineral phases including anthophyllite, wollastonite, and silica. On the other hand, the geopolymerization process was initiated by mixing the calcined marl sample with the alkali activation solution at different mixing ratios and varying curing conditions. The compressive strength measurements indicate that 750 °C, 12 M NaOH, 0.6 SS/SH mass ratio, 2 S/L mass ratio, 80 °C curing temperature, 12 h curing time, and 28 days aging time are considered all to be the optimum synthesis conditions of the Abu-Tartur calcined marl-based geopolymer. Full article

The spread of charging infrastructure (CIS) for battery electric vehicles is crucial for coping with the increasing number of electric vehicles. Therefore, the selection of ideal (fast-) charging locations determines acceptance, utilization and, thus, the economic viability of a single site or the whole charging network. The methodology of the Integrated Model Approach STELLA (STELLA is the acronym for the German term “STandortfindungsmodell für ELektrische LAdeinfrastruktur”) for site identification of CIS uses reliable methods of traffic modeling such as the classic four-step traffic modeling in a new context to enable statements regarding the positioning of CIS. Because only (electric) motorized individual traffic is of importance for CIS, the share of trips is calculated by differentiating the modal split between various transport groups. To estimate the public transport share in the model approach STELLA there are several factors used. One aspect is the accessibility of stops, which can be determined with accessibility radii one the one hand, and with network analyses on the other hand. The methods have been evaluated for the region of Nuremberg. Depending on the spatial characteristics there is a difference of up to 60% between the two methods in the area covered by public transport. Therefore, the network analysis leads to a more accurate estimation of the public transport share. The modal split determination is then implemented in the model approach STELLA, which is currently developed for a planning area covering the entire territory of the Federal Republic of Germany. Full article

This study describes a quantitative method using thermography to measure the thermal properties of building fabrics that are subjected to non-steady state heat flow due to consistently changing meteorological conditions. The method includes two parts. First, the convection heat transfer coefficient is measured by thermography and heat flux meters on a small segment of the examined building fabric with uniform surface temperature. Then, thermal properties of large building fabrics are evaluated by thermography. The two parts are measured simultaneously. The method was tested on 140/160/190 mm thick massive laminated spruce timber walls of a test facility cabin located in Östersund, Sweden. The results varied by only a few percent in comparison to validation measurements performed with heat flux meters and in comparison, to values from the literature. Due to rapid changes in weather conditions the measured values had large disparity, but still a linear regression with low confidence interval was obtained. Obtaining an accurate value of convection heat transfer was important for achieving high measurement accuracy and, therefore, the value of this parameter should be measured. Other important factors to consider are solar radiation, reflected infrared (IR) radiation from nearby objects and the number of thermal images. Full article

Reinforced concrete pipe (RCP) standard guidelines and industry practice have rather been disconnected from the end-users’ expectations. No genuine effort has so far been made to create synergy between the expertise gained and advances made around the world. With the advent of strong competition from flexible pipe products and changing end-user expectations, a critical look at the current state-of-the-art is needed. In the present paper, RCP standards from a study area representing a quarter of the world’s population (Canada, United States, United Kingdom, China, Australia and New Zealand) were critically analyzed. Comparisons were made in terms of product and material requirements, structural load testing, hydrostatic performance, and durability requirements. It is shown that the RCP sector lags modern developments in concrete technology, standard code advances and materials innovations. The analysis also revealed various knowledge gaps in terms of the mechanical, hydrostatic and durability performance of RCP. Recommendations emanating from this critical analysis aim at tailoring performance-based guidelines that can better capture current market needs and user expectations. Full article

Metakaolin is the only major natural pozzolan to be specified for use as a supplementary cementitious material in the United States. As a result, the metakaolin market for concrete has grown dramatically in the past 20 years. As of now, the specifications of up to 16 state departments of transportation allow for the use of commercially-available and high-reactivity metakaolin products. However, to the best of the authors’ knowledge, no study has been performed to evaluate whether these products are comparable in their performance. Three commercially-available (U.S.) metakaolin products, each replacing 10%, 15%, and 20% of the cement content in concrete and mortar mixtures are studied. Concrete mixtures contained a cementitious content of 422 kg/m³, a coarse aggregate fraction of 985 kg/m³, and a water-to-cementitious ratio equal to 0.43. Varying levels of a superplasticizer were used to maintain a uniform workability between mixtures. Each mixture was subjected to the following tests: compression, split-cylinder tension, modulus of rupture, dynamic elastic modulus, rapid chloride-ion penetrability, alkali–silica reactivity, sulfate resistance, the coefficient of thermal expansion, and drying shrinkage. Benefits from the inclusion of metakaolin were highly product-dependent and include increases in mechanical strength. All metakaolin supplemented concrete mixtures benefitted from decreased permeability and increased resistance to chemical attacks, with the exception of the sulfate resistance of mortars including a metakaolin product with high fineness. The inclusion of any metakaolin at any replacement level increased the coefficient of thermal expansion of concrete specimens. Reasons for difference in performance between products are discussed, and predictors of quality are recommended. Full article