Infrastructures, Volume 4, Issue 4 (December 2019) – 19 articles

The super-speed tube transport (SSTT) system, which enables high-speed transportation in a partially vacuumed tube by minimizing the air resistance, is drawing attention as a next-generation transportation system. To evaluate the applicability of concrete as a material for the system, the effect of cracks on the airtightness of the system needs to be considered. This study aims to establish an analytical relationship between the cracks induced on a concrete tube structure and the system airtightness. An analytical model for the leakage rate through the concrete cracks is first applied to establish a differential equation, which can help determine the air flow rate into the concrete tube structure through the cracks. A mathematical formula for predicting the internal pressure changes over time in the concrete tube structure is then derived. The effect of crack development on the system airtightness is assessed through parametric analysis and a crack index for describing the extent of crack development is proposed by investigating the correlation with the system airtightness. Finally, assuming that the cracks due to external loadings are closely related to the displacement, the correlation between displacements and the airtightness of concrete tube structures is demonstrated through a set of experimental tests. As a result, the necessity of crack analysis for evaluation of the airtightness performance is emphasized. Full article

The piled raft foundations are widely used in infrastructure built on soft soil to reduce the settlement and enhance the bearing capacity. However, these foundations pose a potential risk of failure, if dynamic traffic loading and ground conditions are not adequately accounted in the construction phase. The ground conditions are complex because of frequent groundwater fluctuations. The drawdown of the water table profoundly influences the settlement and load sharing capacity of piled raft foundation. Further, the dynamic loading can also pose a potential risk to these foundations. In this paper, the two-dimensional finite element method (FEM) is employed to analyze the impact of water drawdown and dynamic loading on the stability of piled raft. The seismic response of piled raft is also discussed. The stresses and deformations occurring in and around the raft structure are evaluated. The results demonstrate that water drawdown has a significant effect on the stability and seismic response of piled raft. Various foundation improvement methods are assessed, such as the use of geotextile and increasing thickness of the pile cap, which aids of limiting the settlement. Full article

Climate change already has far-reaching impacts on the oil industry, putting the operation, reliability, and growth of the sector at risk. Oil infrastructure has multi-decadal lifetime projections; thus, climate change and extreme weather events such as extreme temperatures, hurricanes, high winds, lightning strikes, storm surges, flooding, etc., pose an extra challenge to the oil supply chain, from upstream to downstream. In this paper, we review the climate change risk assessment frameworks, the impacts of climate change on oil infrastructure, and we identify gaps in the current knowledge, also suggesting future search directions on adapting the oil sector to climate change. The work overviews linkages between climate and oil industry design, operational, and service thresholds in a comprehensive hazard threshold matrix. Existing risk assessment methodologies that account for existing regulatory frameworks and interdependencies with other infrastructures are studied, leading to mitigation, adaptation, and sector resilience recommendations. Full article

Paving blocks are today a popular paving solution for urban surfaces. Considering the wide variety of products currently on the market, it is possible to build pavements that differ in terms of functionality, bearing capacity, skid resistance, visual impact, and aesthetic integration with the surrounding landscape. Interlocking concrete paving block is the most common construction technology considering its low cost and its easy installation. Different wastes and second-hand materials have recently been tested in order to completely or partially replace the raw materials used for the production of paving blocks. In this paper, a waste basalt powder is used for the production of alternative paving blocks through the alkali-activation process. Two different synthetic blocks were produced, with and without aggregates. Taking into account the EN 1338 standard for concrete paving blocks, a complete laboratory characterization is proposed for the two experimental blocks. Tests highlighted positive results and downsides that need to be optimized in order to convert the laboratory production to an industrial scale. Full article

Small unmanned aerial system(s) (sUAS) are rapidly emerging as a practical means of performing bridge inspections. Under the right condition, sUAS assisted inspections can be safer, faster, and less costly than manned inspections. Many Departments of Transportation in the United States are in the early stages of adopting this emerging technology. However, definitive guidelines for the selection of equipment for various types of bridge inspections or for the possible challenges during sUAS assisted inspections are absent. Given the large investments of time and capital associated with deploying a sUAS assisted bridge inspection program, a synthesis of authors experiences will be useful for technology transfer between academics and practitioners. In this paper, the authors list the challenges associated with sUAS assisted bridge inspection, discuss equipment and technology options suitable for mitigating these challenges, and present case studies for the application of sUAS to several specific bridge inspection scenarios. The authors provide information to sUAS designers and manufacturers who may be unaware of the specific challenges associated with sUAS assisted bridge inspection. As such, the information presented here may reveal the demands in the design of purpose-built sUAS inspection platforms. Full article

In India, damage cause by some major earthquakes, such as India/Nepal 2015, Sikkim 2011, Kashmir 2005, Bhuj 2001, Latur 1993, and Uttarkashi 1991, have raised alarms to professionals. The probability of seismic risk is higher in more densely populated Indian cities, such as Bhuj, Kashmir, Sikkim, Uttarkashi, as they come under the highest seismicity zone in India. Therefore, our primary interest is to investigate the seismic performance evaluation of the buildings in these seismic prone areas. Significant research has been conducted on the seismic performance of existing buildings. However, investigations on the seismic performance of a building with different country codes for the same earthquake event has not been explored, which is crucial in providing a deeper knowledge of the seismic performance of buildings. This paper presents a comparative study of an Ordinary Moment Resistant Frame (OMRF) building designed using three major codes, Indian (IS: 456-2000, IS: 1893-2002), British (BS: 8110-1997) and European (EC-2, EC-8). Six typical building models considered with earthquake (WiEQ), and without earthquake (WoEQ), and their assessments were interpreted using non-linear static analysis for determining their seismic performance. Seismic performance is compared in terms of base shear coefficient (BSC) and drift ratio that shows WiEQ models, at the drift ratio of 1.5%, the BSC was as follows; 0.78, 0.88, and 0.96 for the models designed for British, Euro, and Indian codes, respectively. The results show that the building models, that have been designed for the Indian codal provisions for both cases, performed well as compared to the other country codes. Base shear and drift ratio are the vital parameters that vary considerably among the building models. This aspect of the Indian code makes it a safer design methodology with higher reserve strength and a reasonably good displacement capacity before reaching the Collapse Prevention (CP) performance level. Full article

The evaluation of portal locations for mountain tunnels is among the most crucial considerations during route selection and structural layout planning. The development of spatial information technology has provided a more objective approach for assessing the slope stability of potential portal sites. The simulations in such studies have been performed to evaluate potential hazards and slope stability. However, potential instabilities resulting from excavation are seldom considered in these studies. Therefore, a method based on spatial information technology was developed in this study for considering the potential impact of the direction and depth of excavations on portal stability. An analysis method for an infinite slope was integrated into the geographical information system for evaluating the stability of critical wedges. The proposed method provides a reasonable estimation comparable with that provided by the conventional slice method. The results of applying this method to six mountain tunnel portals where slope instability occurred during construction indicate that the actual outcomes agreed with the predicted outcomes. For potential portal site evaluation, the proposed method facilitates the rapid estimation of safety factors for various slope designations, which is useful for site selection. Full article

Accelerated curing is used for mass production in the precast concrete industry. Autogenous shrinkage and drying shrinkage occur in concrete, during and after accelerated curing. Thus, thermal cracks may occur in concrete due to both heating and cement hydration at early age, whereas drying shrinkage causes cracks after demolding. Ground granulated blast-furnace slag cement (GGBS), a byproduct in steel manufacture, has been used to improve concrete strength development during accelerated curing but poses a challenge of increased shrinkage. In this paper, two types of granulated blast-furnace slag cements were used to study mechanical and shrinkage properties of water cured and concrete subjected to accelerated curing. Limestone powder and gypsums, with two different types of fineness, were other additives used. An accelerated one day curing cycle was adopted that consisted of a 3 h delay period, heating to 65 °C, a peak temperature maintained for 3 h, and, finally, cooling. The results indicated that increment in gypsum fineness increased concrete expansion at one day for both sealed and accelerated cured concrete. In drying condition, similar shrinkage was observed. The addition of gypsum provided slightly lower shrinkage, and this may help to reduce cracking of concrete. Limestone powder improved concrete strength at early age. The difference in blast-furnace cement fineness did not have significant differences in compressive strengths, especially at 28 days. Full article

It is believed that isolated subsurface structures of an infrastructure do not ventilate through opening(s) in manhole covers. The literature has almost no information on this topic. This study reports on considerations involved in the development and utilization of a method to study this question. Carbon monoxide (CO) is readily obtainable in engine exhaust, easily detectable at very low concentration, and is relatively safe to handle, which makes it ideal for use as a tracer gas. Transfer into the airspace of the structure was carried out using metal tubing. This study examined the engine operating time and the number of openings in a manhole cover. CO was measured using four instruments in the vertical profile. It was found to generally decrease in a narrow band, initially linearly through a curvilinear region and a linear tail. Clearance of most of the contaminant occurred rapidly during the first part of the process. A decrease to 25 ppm required from 439 min (7 openings) to 1118 min (1 opening). Ambient temperature and near-surface air flow likely influenced these values. The measurement profiles strongly suggest that the atmosphere in the airspace was rapidly and thoroughly well-mixed. The methodology developed and reported here is suitable for a more expanded investigation, the intent being to identify modifications of the design to optimize the process. Full article

Utilizing recycled asphalt pavements (RAP) in pavement construction is known as a sustainable approach with significant economic and environmental benefits. While studying the effect of high RAP contents on the performance of hot mix asphalt (HMA) mixes has been the focus of several research projects, limited work has been done on studying the effect of RAP fraction and particle size on the overall performance of high RAP mixes produced solely with either coarse or fine RAP particles. To this end, three mixes including a conventional control mix with no RAP, a fine RAP mix (FRM) made with 35% percent fine RAP, and a coarse RAP mix (CRM) prepared with 54% of coarse RAP were designed and investigated in this study. These mixes were evaluated with respect to their rutting resistance, fatigue cracking resistance, and low temperature cracking performance. The results indicate that although the CRM had a higher RAP content, it exhibited better or at least the same performance than the FRM. The thermal stress restrained specimen testing (TSRST) results showed that the control mix performed slightly better than the CRM, while the FRM performance was adversely affected with respect to the transition temperature midpoint and the maximum tensile stress temperature. Both of the RAP incorporated mixes exhibited better rutting resistance than the control mix. With regard to fatigue cracking, the CRM performed better than the FRM. It can be concluded that the RAP particle size has a considerable effect on its contribution to the total binder content, the aggregate skeleton of the mix, and ultimately the performance of the mix. In spite of the higher RAP content in the CRM versus FRM, the satisfactory performance observed for the CRM mix indicates a great potential in producing high RAP content mixes through optimizing the RAP particle size and content. The results also suggest that the black curve gradation assumption is not representative of the actual RAP particles contribution in a high RAP mix. Full article

Numerous post-windstorm investigations have reported that windborne debris can cause costly damage to the envelope of buildings in urban areas under strong winds (e.g., during hurricanes or tornados). Thus, understanding the physics of debris flight is of critical importance. Previously developed numerical models describing debris flight physics have not been validated for the complex urban flow environment; such a validation requires experimentally measuring the debris flight trajectory in wind tunnel tests. In this context, this paper proposes a debris measurement algorithm using stereophotogrammetry. This algorithm aims to determine the six-degree-of-freedom (6-DOF) trajectory and velocity of flying debris, addressing the research gap, i.e., the lack of an algorithm/software for measuring three-rotational-DOF using stereophotogrammetry. This is a civil engineering problem, but computer graphics is the foundation to solve it. This paper focuses on the theoretical development of the algorithm. The developed algorithm can be readily implemented in modern wind tunnel experiments. Full article

Unprecedented flooding events put dams and downstream communities at risk, as evidenced by the recent cases of the Oroville and Whaley bridge dams. Empirical models may describe expected ‘normal’ dam behaviour, but they do not account for changes due to recurring extreme weather events. Numerical modelling provides insights into this, but results are affected by the chosen material properties. Long-term field monitoring data can help with understanding the mechanical behaviour of earthfill dams and how this is affected by the environment over decades. We analyse the recorded settlements for one of the largest earthfill dams in Europe. We compare the evolution of these settlements to the reservoir level, rainfall, and the occurrence of earthquakes for a period of 31 years after first impoundment. We find that the clay core responds to the reservoir fluctuations with an increasing (from 0 to 6 months) time delay. This is the first time that a change in the behaviour of a central clay core dam, as observed from field data, is reported in the international literature. Seepage rates, as recorded within the drainage galleries, are directly affected by cumulative rainfall depths exceeding 67 mm per fortnight. Full article

Wastewater infrastructure systems deteriorate over time due to a combination of aging, physical, and chemical factors, among others. Failure of these critical structures cause social, environmental, and economic impacts. To avoid such problems, infrastructure condition assessment methodologies are developing to maintain sewer pipe network at desired condition. However, currently utility managers and other authorities have challenges when addressing appropriate intervals for inspection of sewer pipelines. Frequent inspection of sewer network is not cost-effective due to limited time and high cost of assessment technologies and large inventory of pipes. Therefore, it would be more beneficial to first predict critical sewers most likely to fail and then perform inspection to maximize rehabilitation or renewal projects. Sewer condition prediction models are developed to provide a framework to forecast future condition of pipes and to schedule inspection frequencies. The objective of this study is to present a state-of-the-art review on progress acquired over years in development of statistical condition prediction models for sewer pipes. Published papers for prediction models over a period from 2001 through 2019 are identified. The literature review suggests that deterioration models are capable to predict future condition of sewer pipes and they can be used in industry to improve the inspection timeline and maintenance planning. A comparison between logistic regression models, Markov Chain models, and linear regression models are provided in this paper. Artificial intelligence techniques can further improve higher accuracy and reduce uncertainty in current condition prediction models. Full article

In this paper, the carbonation depths of glazed hollow bead insulation concrete (GHBC) and normal concrete (NC) at different carbonation ages are tested. The microstructure of GHBC and NC before and after carbonation were observed and compared by mercury intrusion porosimetry (MIP), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The results showed that NC had better carbonation resistance than GHBC, and GHBC had a carbonation depth of 1.61 times than that of NC at 28 days accelerated carbonation experiment. The microstructural analysis showed that with the decrease of porosity of the samples, the carbon content and CaCO₃ content increased after carbonation. The porosity of NC decreased from 14.36% to 13.53%, the carbon content increased from 4.42% to 5.94%, and the CaCO₃ content increased from 18.5% to 56.0%. The porosity of GHBC decreased from 22.94% to 20.71%, the carbon content increased from 4.97% to 5.31%, and the CaCO₃ content increased from 70.0% to 82.0%. The above results showed that carbon reacts with hydration products 3CaO·SiO₂, 2CaO·SiO₂, and Ca(OH)₂ to produce a large amount of CaCO₃ which causes a large amount of pores to be filled and refined hence the porosity and pore size were reduced leading to increase in the compactness of the material. From the results obtained, the carbonation depth prediction formula of glazed hollow bead insulation concrete was developed, and carbonation life was predicted. Full article

Most gravity dams have been designed and built during the past century with methods of analysis that are now considered inadequate. In recent decades, knowledge of seismology, structural dynamics and earthquake engineering has greatly evolved, leading to the evaluation of existing dams to ensure public safety. This study proposes a methodology for the proper modelling and characterisation of the uncertainties to assess the seismic vulnerability of a dam-type structure. This study also includes all the required analyses and verifications of the numerical model prior to performing a seismic fragility analysis and generating the corresponding fragility curves. The procedure presented herein also makes it possible to account for the uncertainties associated with the modelling parameters as well as the randomness in the seismic solicitation. The methodology was applied to a case study dam in Eastern Canada, whose vulnerability was assessed against seismic events with characteristics established by the current safety guidelines. Full article

In this study, the performance of an islanded gas turbine power generation system in Malaysia was investigated. Considering the low fuel efficiency of the plant during peak and part-load operations, an economic analysis was also carried out, over the period of one year (2017). The case study was conducted on the isolated electrical network of the Universiti Teknologi PETRONAS (UTP), which consists of two gas turbine units with a total capacity of 8.4 MW. Simple performance indicators were developed to assess the performance, which can also be applied to other power stations in Malaysia and elsewhere. Meanwhile, the economy of variable load operations was analyzed using the statistical data of generation, fuel consumption, and loads. The study reveals that the capacity factor of the microgrid in the period was between 52.77–63.32%, as compared to the industrial best practice of 80%. The average plant use factor for the period under review was 75.04%, with a minimum of 70.93% and a maximum of 78.61%. The load factor of the microgrid ranged from 56.68–65.47%, as compared to the international best practice of 80%, while the utilization factor was between 44.22–67.655%. This study further reveals that high fuel consumption rates, due to the peak and part-load operations, resulted in a revenue loss of approximately 17,379.793 USD per year. Based on the present performance of the microgrid, suggestions are made for the improvement of the overall performance and profitability of the system. This work can be valuable for microgrid utility research to identify the most economical operating conditions. Full article

Underground infrastructure is a critical component of the basic utility services provided to society. The single largest threat to the safety of underground utility lines is being struck by construction earthwork projects. One of the causes of this problem is miscommunication between utility owners and contractors. Therefore, it is vitally important to coordinate resources, share information, and ensure efficient communication between construction personnel and utility owners. Geographic information systems (GIS) provide a solution for interoperability in the construction industry. Applying such technologies in the field of underground construction requires accurate and up-to-date information. Augmented reality (AR) has been identified as a technique that could enhance information extraction from the virtual world to the real world and improve the access and utilization of information. However, there is currently limited research that has integrated AR and GIS and evaluated the effectiveness and usability of the combination in this domain. The main objective of this research was to develop an integrated AR-GIS for mapping and capturing underground utilities using a mobile device. The data are shared instantaneously with other stakeholders through a cloud-based system. In order to achieve these objectives, a design research approach was utilized to develop and evaluate a mobile extended-reality (XR-GIS) application. Validation of the XR-GIS was conducted through a focus group discussion and a questionnaire. The results revealed that 86% of the participants validated the system’s adaptivity to the underground construction. We can conclusively say that this research has produced an efficient solution for data collection and sharing among stakeholders in the underground construction industry. Full article

Worldwide, infrastructure contains millions of isolated subsurface structures. Most, if not all, meet requirements for classification as confined spaces. Workers routinely enter and work in these structures. Ventilation of these spaces by air exchange induced by natural forces was documented first in 1936. The mechanism of the process remains to be discovered. This investigation utilized ‘smoke’ tubes to visualize air motion and video capture techniques to record the process. Air moved across the surface of the ground and unpredictably entered the airspace when a single opening in the manhole cover was present. The process is discrete and not continuous. Air moved downward linearly or in circular motion, and moved across the underside of the manhole cover in the direction opposite airflow and down the sidewall of the structure. This produced the rapid mixing in the airspace observed instrumentally. For two openings, entry was more aggressive and predictable. Separation between the openings influenced exchange. Closer spacing (center + circumference) produced better ventilation than wider spacing (circumferential openings opposite each other). Optimizing naturally induced ventilation of these structures has profound importance to minimize risk to passersby and workers who enter and work in them. Full article

Improving the resilience of infrastructures is key to reduce their risk vulnerability and mitigate impact from hazards at different levels (e.g., from increasing extreme events, driven by climate change); or from human-made events such as: accidents, vandalism or terrorist actions. One of the most relevant aspects of resilience is preparation. This is directly related to: (i) the risk prediction capability; (ii) the infrastructure monitoring; and (iii) the systems contributing to anticipate, prevent and prepare the infrastructure for potential damage. This work focuses on those methods and technologies that contribute to more efficient and automated infrastructure monitoring. Therefore, a review that summarizes the state of the art of LiDAR (Light Detection And Ranging)-based data processing is presented, giving a special emphasis to road and railway infrastructure. The most relevant applications related to monitoring and inventory transport infrastructures are discussed. Furthermore, different commercial LiDAR-based terrestrial systems are described and compared to offer a broad scope of the available sensors and tools to remote monitoring infrastructures based on terrestrial systems. Full article