Infrastructures, Volume 7, Issue 12 (December 2022) – 15 articles

Determining the material properties and existing capacity of concrete infrastructure using nondestructive techniques is challenging due to evolving design requirements, unknown as-built conditions, and ongoing maintenance and deterioration. Concrete’s material properties, including density, porosity, and compressive strength, are usually determined by mechanical testing, but being able to measure these properties noninvasively could aid engineers in maintaining and designing concrete infrastructure. Research into nondestructive methods for determining material properties of concrete has shown relationships between mechanical properties and ground penetrating radar (GPR) properties such as dielectric constant, attenuation, and instantaneous amplitude. We investigated direct relationships between dielectric constant and the density, porosity, and compressive strength of 23 mature concrete samples with varying mix designs using a commercial 1 GHz GPR. In normal-weight concrete, weak trends were seen between a dielectric for compressive strength ($R^2=0.76$) and one for density ($R^2=0.64$), whereas no significant trend was found with porosity ($R^2=0.52$). The GPR unit used provides acceptable data but has limited resolution for analyses and utility. The dielectrics showed distinct clustering by mix type—particularly the inclusion of materials such as blast furnace slag. While demonstrating that the dielectric constant is a candidate for rapid concrete comparisons, there is also a demonstrated need for further investigation of the complex relationships between mechanical and electromagnetic properties in concrete. Full article

Plastic waste (PW) constitutes a nuisance to our environment despite several efforts to reduce, reuse and recycle it. This study experimentally explores the possibility of storing plastic waste within a cement-stabilised soil that can be used as a road pavement layer material without adversely affecting the geotechnical characteristics of the stabilised soil. The soil is an A-2-6 soil, according to classification by the American Association of State Highway and Transportation Officials (AASHTO). Compaction characteristics, the California bearing ratio (CBR) and the unconfined compressive strength (UCS) of soil with 10% cement were determined for the 0, 2, 5, 10 and 15% addition of PW. The cementing of soil particles, which played a vital role in enhancing its strength on the addition of cement, may have been activated by the pozzolanic reaction between cement and soil particles. However, the addition of PW to this cement-stabilised mix led to a decrease in strength parameters at all variations. The soil with 10% cement and 2% PW yielded higher strength when compared to other mix ratios with PW and is suitable for use as a layer material in road pavement construction. As a sustainable strategy for PW management in developing nations, the usage of PW in cement-stabilised soil layer is recommended. Full article

Damage to devices installed in electric substations, which have shown vulnerable behaviour under strong earthquakes in the last decades, may endanger power delivery in the emergency phases during and after an earthquake. Within seismic risk assessment of power networks, the definition of the fragility functions of electric equipment is paramount. However, in the current literature the availability of such fragility models for some specific electric substation components, including instrument transformers, is relatively limited, this being the reason behind the deployment of the current experimental and numerical research endeavour. Two voltage transformers and two current transformers having different system voltage levels (respectively in the high voltage HV and extra-high voltage EHV ranges) were subjected to shake table tests, and the experimental results were used to calibrate the corresponding 3D numerical models developed in OpenSees. A number of nonlinear dynamic analyses carried out within a multiple-stripe analysis (MSA) framework allowed the derivation of 16 fragility curves for the four transformers in both stand-alone and elevated/supported configurations, considering also two different soil types. Based on the derived curves, one of the voltage transformers is expected to experience light or negligible damage due to earthquake shaking, owing to its high resonance frequencies (and hence stiffness), whilst the remaining three devices may suffer moderate damage under medium to strong shaking intensities; however, their seismic risk is in effect mitigated by the presence of the typically employed supporting column. Comparison against models available in the literature lent valuable reassurance on the adequacy of the employed methodology and the reliability of the derived fragility curves. Full article

Geopolymer concrete is concrete made from industrial materials, such as fly ash, GGBS, silica fume, and metakaolin, used as a cement alternative. In this study, geopolymer concrete will be based on fly ash as a binder material, alkaline activators of sodium hydroxide and sodium silicate, GPC beams of dimensions 800 mm × 250 mm × 100 mm, circular columns with diameter 350 mm and depth of 700 mm and GPC slabs of dimensions 500 mm × 500 mm × 100 mm are all cast with fly ash content of 350 kg/m³. The ratio of alkaline solution to fly ash was equal to 0.5 and was kept constant, and the Na₂SiO₃-to-NaOH ratio was 2.5 and the NaOH molarity was kept constant at 12 M. The beams reinforcement was changed to study the shear and flexural behaviour, and the slabs and columns reinforcement ratio was kept constant. The load capacity, stress–strain behaviour of the GPC and load-deflection behaviours of the members were also examined. The results showed that reinforced geopolymer members can be used as an alternative to reinforced concrete structural members, but they are more expensive than reinforced concrete. Further study is recommended to provide more practical design recommendations for incorporating geopolymer concrete into structural elements in order to accelerate the adoption of this concrete for large-scale field applications in the future. Full article

The present study focused on the design of geothermal energy piles based on cone penetration test (CPT) data, which was obtained from the Perniö test site in Finland. The geothermal piles are heat-capacity systems that provide both a supply of energy and structural support to civil engineering structures. In geotechnical engineering, it is necessary to provide an efficient, reliable, and precise method for calculating the group capacity of the energy piles. In this research, the first aim is to determine the most significant variables required to calculate the energy pile capacity, i.e., the pile length (L), pile diameter (D), average cone resistance ($q_{c0}$), minimum cone resistance ($q_{c1}$), average of minimum cone resistance ($q_{c2}$), cone resistance ($q_c$), Young’s modulus ($E$), coefficient of thermal expansion (${\alpha }_c$), and temperature change ($\Delta T$). The values of q_c0, q_c1, q_c2, q_c, and E are then employed as model inputs in soft computing algorithms, which includes random forest (RF), the support vector machine (SVM), the gradient boosting machine (GBM), and extreme gradient boosting (XGB) in order to predict the pile group capacity. The developed soft computing models were then evaluated by using several statistical criteria, and the lowest system error with the best performance was attained by the GBM technique. The performance parameters, such as the coefficient of determination (R²), root mean square error (RMSE), mean absolute error (MAE), mean biased error (MBE), median absolute deviation (MAD), weighted mean absolute percentage error (WMAPE), expanded uncertainty (U₉₅), global performance indicator (GPI), Theil’s inequality index (TIC), and the index of agreement (IA) values of the testing data for the GBM models are 0.80, 0.10, 0.08, −0.01, 0.06, 0.21, 0.28, −0.00, 0.11, and 0.94, respectively, demonstrating the strength and capacity of this soft computing algorithm in evaluating the pile’s group capacity for the energy pile. Rank analysis, error matrix, Taylor’s diagram, and the reliability index have all been developed to compare the proposed model’s accuracy. The results of this research also show that the GBM model developed is better at estimating the group capacity of energy piles than the other soft computing models. Full article

New technologies such as the I-BIM (Infrastructure Building Information Modeling) are radically changing the infrastructure design and construction sector. In this study, the I-BIM approach has been used for the design of a portion of the future Bologna’s Red Tramway Line. Starting from the topographical survey of the area, a “federated” model was created, aggregating in a single digital environment all the models inherent to the individual disciplines involved. Interference analysis (Clash Detection) between the various disciplines was performed, subject to the preparation of a coordination matrix and the temporal simulation of the worksite phases (BIM 4D). The results have shown that the I-BIM approach represents a powerful tool for optimizing and validating infrastructure design, allowing users to see how the infrastructure integrates and fits into the real 3D environmental context. Full article

Wind and/or earthquake-imposed loadings on two dynamically similar adjacent buildings cause vigorous shaking that can be mitigated using energy dissipating devices. Here, the vibration response control in such adjacent structures interconnected with semi-active magneto-rheological (MR) dampers is studied, which could also be used as a retrofitting measure in existing structures apart from employing them in new constructions. The semi-active nature of the MR damper is modeled using the popular Lyapunov control algorithm owing to its least computational efforts among the other considered control algorithms. The semi-active performance of the MR damper is compared with its two passive states, e.g., passive-off and passive-on, in which voltage applied to the damper is kept constant throughout the occurrence of a hazard, to establish its effectiveness even during the probable electric power failure during the wind or seismic hazards. The performance of the MR damper, in terms of structural response reduction, is compared with other popular energy dissipating devices, such as viscous and friction dampers. Four damper arrangements have been considered to arrive at the most effective configuration for interconnecting the two adjoining structures. Structural responses are recorded in terms of storey displacement, storey acceleration, and storey shear forces. Coupling the two adjacent dynamically similar buildings results in over a 50% reduction in the structural vibration against both wind and earthquake hazards, and this is achieved by not necessarily connecting all the floors of the structures with dampers. The comparative analysis indicates that the semi-active MR damper is more effective for response control than the other passive dampers. Full article

Within any ecosystem, information sharing is essential. In this paper, the Swedish gravel road ecosystem is studied, where information plays a crucial role for the effective management of operations and maintenance. However, efficient information sharing is not enabled due to the lack of appropriate information systems. For addressing this issue, this paper intends to elicit information needs of gravel road stakeholders to support the design of a cloud-based information system. The main purpose is to explore the information needs of stakeholders within the Swedish gravel road ecosystem. Data were collected through in-depth semi-structured interviews with 11 participants representing key stakeholders in the ecosystem. Template analysis was used for analyzing the interview results. The major findings were a set of information needs covering road identification and condition, weather conditions, accessibility and traffic, maintenance policy, and sensor data. The results form a comprehensive information model for the further development of a cloud-based gravel road management system that would contribute to increased traffic safety and comfort, lower maintenance and management costs, and better decision-making abilities. Full article

One of the most interesting applications of Structural Health Monitoring (SHM) is the possibility of providing real-time information on the conditions of civil infrastructures during and following disastrous events, thus supporting decision-makers in prompt emergency operations. The Bayesian decision theory provides a rigorous framework to quantify the benefit of SHM through the Value of Information (VoI) accounting for different sources of uncertainties. This decision theory is based on utility considerations, or, in other words, it is based on risk. Instead, decision-making in emergency management is often based on engineering judgment and heuristic approaches. The goal of this paper is to investigate the impact of different decision scenarios on the VoI. To this aim, a general framework to quantify the benefit of SHM information in emergency management is applied to different decision scenarios concerning bridges under scour and seismic hazards. Results indicate that the considered decision scenario might tremendously affect the results of a VoI analysis. Specifically, the benefit of SHM information could be underestimated when considering non-realistic scenarios, e.g., those based on risk-based decision-making, which are not adopted in practice. Besides, SHM information is particularly valuable when it prevents the selection of suboptimal emergency management actions. Full article

Offsite construction has become popular in recent times due to the numerous benefits it offers compared to traditional construction methods. This paper explores the different offsite construction methods, the motivations for adopting these approaches, and the cost-effectiveness of these methods in the UK housing sector using multiple case studies. Firstly, the literature and data were obtained from various sources including professional body reports, industry reports, government websites, and journal articles. Following the review, twelve completed housing projects from the UK which used offsite construction approaches were analyzed. The review of these projects showed that different offsite methods were used in these projects. These include Structural Insulated Panels (SIPs), Timber Frames, Precast Concrete, Steel Frames, Volumetric Construction, Gyproc Habito Plasterboards, and Light Gauge Steel (LGS) technology. The key motivations for adopting offsite construction in these projects include the speed of construction, durability of the products, aesthetic considerations, thermal quality, low air leakage requirements, and quality of construction. Of the 12 cases, only two recorded a higher cost for the offsite construction method compared with the alternative using traditional approaches. The outputs of this paper provide evidence-based strategies which would inform practitioners on the best practices for adopting offsite construction methods and what to expect. Full article

Concrete delamination detection using unmanned aerial vehicle (UAV)-mounted infrared cameras has proved effective in recent research. However, most studies used expensive research-grade infrared cameras and proprietary software to acquire images, which is hard to implement in state departments of transportation (DOTs) due to the lack of specialty professionals. Some state DOTs started deploying lightweight UAV-based consumer-grade infrared cameras for delamination detection. Quantitative performance evaluation of such a camera in concrete delamination detection is lacking. To fill this gap, this study intends to conduct a comprehensive assessment of the consumer-grade camera benchmarked against the results of a research-grade camera to see the practicality of using the small and low-cost camera in concrete delamination detection. Data was collected for a slab with mimicked delamination and two in-service bridge decks. For the case of the slab, maximum detectability of 70–72% was achieved. A transient numerical simulation was conducted to provide a supplemental and noise-free dataset to explore detectability accuracy peaks throughout the day. The results of the in-service bridge decks indicated that the consumer-grade infrared camera provided adequate detection of the locations of suspected delamination. Results of both the slab and in-service bridge decks were comparable to those of a research-grade infrared camera. Full article

Concerning one of the most important tasks of road structure management is the development of methods to predict their own functional or physical service life, which allows for objectively evaluating the state of road structures that are being considered or are already in operation with minimal labor and monetary incomes. Fuzzy logic systems constitute one successful methodology used for the valuation of pavement degradation. The clustering that focuses on pavement degradation conditions is normally performed by a visual inspection or using data collected by automated distress measurement equipment. Fuzzy sets theory provides different advantages for including a certain degree of uncertainty in the pavement performance index, subjective analysis, and maintenance assessments and can greatly improve consistency and reduce subjectivity in the degradation process. The main objective of this study was to develop a new fuzzy logic-based model to predict the functional service life of concrete pavement conditions and maintenance action evaluations concerning the airport network of Viña del Mar, Central Chile, and using pavement distress data from the Directorate of Airports, Ministry of Public Works of Chile. The proposed fuzzy logic model can be remarkably beneficial for design, construction, and maintenance, to evaluate design decisions for the measurable and objective valuation of deviations in the quality of construction, and for timely forecasting work based on continuous observing of the current infrastructure system. Full article

For the safe and efficient operation of dams, frequent monitoring and maintenance are required. These are usually expensive, time consuming, and cumbersome. To alleviate these issues, we propose applying a wave-based scheme for the location and quantification of damages in dams. To obtain high-resolution “interpretable” images of the damaged regions, we drew inspiration from non-linear full-multigrid methods for inverse problems and applied a new cyclic multi-stage full-waveform inversion (FWI) scheme. Our approach is less susceptible to the stability issues faced by the standard FWI scheme when dealing with ill-posed problems. In this paper, we first selected an optimal acquisition setup and then applied synthetic data to demonstrate the capability of our approach in identifying a series of anomalies in dams by a mixture of reflection and transmission tomography. The results had sufficient robustness, showing the prospects of application in the field of non-destructive testing of dams. Full article

European countries are characterized by an extensive infrastructural network, mainly built around the 1960s and 1970s. In that period prefabrication processes were starting to gain ground, and one of the most spread and studied typologies of bridges was constituted by reinforced or prestressed concrete decks. Those structures have gone through years of service, which caused the inevitable degradation of the materials and relevant deterioration of structural elements. Moreover, the design and construction processes of that period have soon become obsolete, and the knowledge relative to the influence of detailing increased significantly. One particular element that has been commonly used has been the half-joint, which is easy to prefabricate and has a strategic impact. However, in recent years this solution is showing critical aptitudes in resisting structural degradation and material decay. In addition, structural health monitoring (SHM) strategies are gaining attention since they are a very useful tool for gathering information on the current state of the structure and then for evaluating intervention plans to improve safety. Indeed, existing bridges, despite their working age, are still crucial to the development and sustainability of community life, and their decommissioning would be an act of critical impact on the communities (e.g., economy, logistics, sustainability). This contribution presents the design and the simulation of laboratory tests on half-joints of reinforced concrete beams that will be developed at the Politecnico di Torino in a subsequent step of the present research. They are designed to test and compare different monitoring techniques along with different steel reinforcement configurations. Specifically, the first part of the manuscript focuses on a review of the literature regarding the design, strengthening, and monitoring of half-joints. Subsequently, the laboratory setup to test half-joints is presented along with the numerical simulation to support the experimental design. Laboratory tests will involve the use of monitoring systems to detect the local response of the system and also to propose new solutions specifically for this type of connection using emerging technologies. Numerical collapse simulations show the effect of different reinforcement configurations and the collapse behavior. Full article

Concrete strength gain can be significantly affected by the initial characteristics of the raw materials. Unfortunately, information on the potential influence of the initial water pH on concrete strength gain is still scarce. In this study, the potential effects of the initial water pH on concrete strength gain were investigated using a combination of sensors and a sclerometric test. The impact of initial pH on the strength gain process was investigated using three distinct pH values (4.0, 7.0, and 12). The primary variables examined were pH variations over time, internal temperature, and strength gain. The problem was further examined using a number of statistical techniques, including Single-way Analysis of Variance, Scheffé’s approach, and Correlation Matrixes. When the temperature data from 4.0, 7.0, and 12 pH values were put through the Analysis of Variance, a p-value of 2.4 × 10⁻²⁶¹ was retrieved. Additionally, when the strength gain data from 4.0, 7.0, and 12 pH values were subjected to the Analysis of Variance, a p-value of 2.9 × 10⁻¹⁶⁸ was retrieved. The results showed that the differences in the list data retrieved from the investigated pH values were statistically significant. Based on the results, we can state that the initial pH level in the mixing water can have noticeably varied consequences in terms of the strength gain of the concrete and should be carefully considered during the preparation process of concrete. The findings retrieved from this study provide a piece of useful information in the construction field, especially with concrete strength management. Full article