Journal of Infrastructure Systems

The structural capacity of a pavement has been shown to be an excellent indicator of the required maintenance and expected performance of asphalt pavements, but studies reported in the literature have produced few indices for composite pavement systems. This paper presents a relationship to predict the future functional performance (i.e., the behavior of the surface condition over time) of composite pavements as a function of its structural condition measured using the falling weight deflectometer (FWD). Network-level deflection data were collected using the FWD between the years 2005 and 2007 on approximately 3,700 directional km (2,300 directional miles) of interstate pavements in Virginia. The network of pavements included asphalt, jointed concrete, and composite (asphalt surface over jointed concrete) pavements. The FWD data were then compared with the performance of several pavement segments that received maintenance treatment just before deflection testing. It was found that the measurements obtained using the FWD correlated strongly with the performance of the composite pavements.

Most of the commercially available bridge weigh-in-motion (B-WIM) systems are based on an algorithm developed by Moses. The performance of this method was generally acceptable for estimating gross vehicle weight (GVW) but can be inadequate for estimating single axle load. Two alternative algorithms for the identification of vehicle axle loads are presented in this paper based on field verified simulation model using the semirigid frame system with multiple simplified span bridges. Both algorithms are based on the simulation of the entire bridge, representing realistic boundary conditions, bridge geometry properties, and field environment from field B-WIM testing results. The first alternative algorithm includes adjusting the experimental weight-in-motion (WIM) moment of the testing span from the simulation model to perform vehicle weight calculation. The second algorithm includes applying the simulated influence line from the simulation model to calculate the vehicle weight. Both approaches demonstrate significant improvements on the accuracy of vehicle weight for a bridge on the U.S. Highway 78 (US-78) by B-WIM testing.

As long as motorway concessions are subject to the variability of traffic demand, it is necessary to apply valuation methods that can take into account that uncertainty. In the past, many concession projects have faced an early termination of the contract due to lower traffic than expected. These insolvency situations raise the issue of the compensation to the concessionaire when the contract is prematurely terminated. A methodology based on the real-options approach has been developed in this paper to assess insolvency situations in motorway concessions. Under this approach, the mechanism of compensation can be modeled as an abandonment option, granted by the public administration to the concessionaire, in which the value of the option will depend on the evolution of traffic. This methodology is then applied to the case of a real concession in Spain. The results show a significant value of the abandonment option, which represents an implicit aid from the public administration to the concession. In this way, the methodology presented in this paper can contribute to gaining a better understanding of the risks of motorway concessions and enhancing the transparency in concession contracts.

Infrastructure that meets users’ needs with less complexity can satisfy growing demand and relieve system pressures. Such outcomes are defined as elegant. Unfortunately, social and cognitive biases can inhibit infrastructure stakeholders from achieving these outcomes. In other fields, similar biases are overcome with well-designed choice architecture, which considers how the presentation of choices effects the decisions that are ultimately made. Using a metasynthesis research approach, this article describes cognitive biases that can inhibit elegant infrastructure and then presents strategies to mitigate these biases with choice architecture interventions. The emphasis here is on high-impact decisions with cost-effective and plausible choice architecture interventions. This systematic merging of behavioral science and infrastructure systems is meant to provide readers with the background and examples needed to investigate choice architecture as a strategy to influence the infrastructure outcomes they desire.

Damage to power distribution systems due to hurricanes is likely to increase due to a possible increase in the intensity of tropical cyclones caused by climate change. This will exacerbate the already high cost incurred by utility companies and communities due to damage to distribution systems by hurricanes. Consequently, long-term investment in critical civil infrastructure systems, such as distribution systems, requires long-term planning that incorporates the potential impact of climate change. This can only be achieved through a comprehensive risk analysis framework for evaluating the impact of climate change and studying the effectiveness of various adaptation strategies. This paper presents a framework for incorporating the potential impact of climate change in the reliability analysis of power distribution systems subject to hurricane hazards. The framework incorporates a time-dependent hurricane hazard model, time-dependent fragility model, system reliability evaluation, and a life cycle cost analysis for evaluating the cost-effectiveness of various climate change adaptation strategies. A notional power distribution system located in the hurricane-prone state of Florida is used to demonstrate the proposed framework.

Over the last few years there has been a renewed interest on the use of timber-concrete composite (TCC) structures in bridge decks, possibly because of their cost competitiveness and environmental friendliness. Accordingly, this paper investigates the sustainability of TCC bridge decks under a threefold environmental, economic, and sociocultural perspective. Two different types of decks, which represent the overall characteristics of TCC bridges constructed around the world, are first described. Next, the paper presents a comparative sustainability assessment of two existing concrete bridges and their TCC deck potential alternatives (of the types previously mentioned); a lifecycle methodology, based on standards from the International Organization for Standardization (ISO) and other publications, is followed. The main conclusions are that, when compared with concrete decks, TCC solutions cause less environmental impact and are cost-competitive. Regarding sociocultural impacts, this analysis reveals the lower user-incurred costs of one of the TCC deck types.

Reinforcement bars in concrete are exposed to several actions, such as overloading, fatigue, and corrosion. These actions can lead to a deterioration of the reinforcement bars. However, only advanced stages of damage in the reinforcement will be visible at the surface. Since no suitable commercial nondestructive methods are available yet, the concrete cover must be removed if damage is suspected. The magnetic flux leakage method is a promising approach to solving this problem. A measuring device was developed that enables the simultaneous magnetization of the reinforcement and measurement over a width of 20 cm. To support the user, a software is in development that allows for immediate evaluation and interpretation of the results. The present project aims at demonstrating the value of the magnetic flux leakage method in particular for bridge evaluation.

Strengthening deficient structural reinforced concrete (RC) elements by using externally bonded carbon fiber-reinforced polymer (CFRP) has become a popular method because of CFRP’s superior mechanical properties. However, previous studies have shown that sudden failure due to debonding is the major problem for CFRP-strengthened RC members, especially for the deficient beams. Debonding of CFRP results in sudden fracture of the structural element, and most studies show that it is not easy to predict debonding of CFRP from strain values. In cases that whole surface of the RC member is covered with CFRP strips and U-jacketing is preferred, it is impossible to see the cracks on the surface that may lead to failure of the RC member. Acoustic emission (AE) is known to be a useful method for crack monitoring of an element under load. In this study, in order to understand the behavior of a CFRP U-plate-strengthened RC beam, a specimen strengthened with CFRP U-plate against shear was tested under cyclic loading. AE monitoring was used to obtain types and locations of cracks to correlate them with different load steps and failure mechanisms for the specimen covered with CFRP at its whole beam surface.

Ultrasonic noncontact methods of testing civil engineering materials in air, where both transmission of waves into materials and reception of signals are contactless, are reviewed. A short history and technical details of noncontact methods related to generation, reception, and transmission of waves are presented. Particular attention is devoted to enhancement of the signal-to-noise ratio by using coded signals. Next, examples of currently available solutions dedicated to (1) estimation of bulk properties of materials, (2) evaluation of state of concrete cover, (3) flaw detection, and (4) identification of structural parameters of porous materials are discussed. Applications of laser techniques, classical echo, direct through transmission, and different types of semicontact methods are topics that are not reviewed in this paper. Finally, the benefits and limitations as well as expected directions of further development of the noncontact techniques are indicated.

A large aperture ultrasonic system (LAUS) has been designed and built for testing thick concrete structures. The scalable system consists of 12 ultrasonic units, each hosting 32 individual shear wave transducers with a mechanical dry point contact (DPC) to the concrete surface. The 12 units are attached to the concrete surface using a vacuum case, which holds them in place during operation. Each LAUS unit can be placed individually on the surface to achieve the optimal ultrasonic condition, e.g., to avoid rebars. For the generation of the vacuum, air pressure is supplied to each unit through an air hose. The 12 units define an aperture, which is necessary for fast reconstruction of the subsurface structure. The well-known synthetic aperture focusing technique (SAFT) algorithm has been adopted for this situation, where the individual LAUS units form a linear aperture with not necessarily equidistant spacing between the units. The exact geometrical position of the units, which are individually marked with retroreflective labels, is determined using photographs and image processing. All transducers are synchronized and work either as a transmitter or receiver. A full scan consists of $12\times 11$ recordings, where each unit acts as transmitter once and all others as receivers. An electronic subunit on the back of the ultrasonic device holds the battery and handles data acquisition, synchronization, and data communication. A computer is used as base unit that communicates with each LAUS unit for control and data acquisition, the synchronization is performed by a radio modem that uses a special algorithm similar to a digital phase locked loop (PLL). No wire connections are necessary between the units and the base system. The LAUS system is designed to investigate concrete structures with thicknesses in excess of 2 m, depending on the acoustic condition of the object under investigation. Highly reinforced concrete may have less penetration depth. The LAUS provides quasi-real-time imaging, once the transducers are put in place and the data have been acquired. The first measurements on a foundation slab confirm that the system can register ultrasonic echoes from the back wall at 4 m distance.

Monitoring the condition of concrete bridge decks is essential because bridge decks are deteriorating faster than other bridge components. This study concentrated on bridge deck condition assessment using complementary nondestructive evaluation (NDE) techniques. The assessment had three main components: evaluation of the corrosive environment and corrosion processes, concrete degradation evaluation, and assessment with respect to deck delamination. Five NDE techniques were used: impact echo (IE) to detect and characterize delamination, ground-penetrating radar (GPR) to describe the corrosive environment, measurement of the concrete cover and description of its overall condition, half-cell potential (HCP) to assess corrosion activity, ultrasonic surface waves (USW) to describe concrete quality, and electrical resistivity (ER) to estimate corrosion rate. The ability of NDE methods to objectively characterize deterioration progression is illustrated by the results from four NDE surveys of a bridge in Virginia during a period of five and a half years. The results, which include condition maps and condition indices, demonstrate the ability of NDE technologies to accurately and objectively detect and quantify deterioration progression. Results from periodical NDE surveys show a high potential for development of more realistic deterioration and lifecycle cost models for bridge decks.

A new technology to coat concrete with coherent layers of glass by flame-spraying is currently developed at the Institutes of Building Materials Research and Mineral Engineering of RWTH Aachen University in Germany through a joint program. A major factor influencing the pull-off strength of the flame-sprayed glass coating is thermally induced damage in the underlying concrete substrate. In this article, the authors present a nondestructive test method using single-sided ${}^1\mathrm{H}$ nuclear magnetic resonance (NMR) to evaluate the thermally induced damage in concrete specimens. The particular NMR device used in this project primarily detects water and can qualitatively assess the water content as well as the relative size of water-filled voids such as pores and cracks. To do so, the specimens are water saturated and subsequently analyzed by NMR. Changes in the NMR-signal are interpreted in terms of change in porosity and development of cracks inside the cement stone as a function of depth from the concrete surface.

This paper presents a state-of-the-practice of turnaround maintenance (TAM). It also develops an assessment tool for TAM projects based on quality function deployment (QFD). A modified QFD methodology was used in a case study to investigate how TAM projects can be implemented successfully. To build the QFD matrix, the research identified the technical and stakeholder requirements from three survey sources: literature, industry, and expert opinions. The findings presented three levels of technical requirements: phases (4), attributes (10), and detailed (32). It also defines nine stakeholders (internal and external) with a 24 requirements. In addition, the weights of the technical requirements are found by using the QFD framework. The weights are used to build an assessment matrix based on a Likert scaling. A case study is presented to demonstrate the assessment tool for a petrochemical facility in Saudi Arabia. The assessment found deficiencies in four TAM attributes. Finally, the research proposed actions to improve the deficient attributes. The implementation of this tool helped TAM management to improve their practices of TAM.

In the United States, for road maintenance activities, state departments of transportation (DOT) use either in-house resources or outsource to private contractors under various methods, such as method-based contracting (MBC), performance-based contracting (PBC), the hybrid method, lane rental, cost plus time, or incentives/disincentives, etc. In a literature review, factors were identified that affect the selection of the maintenance methods as well as their benefits. This study conducted a survey with state DOT maintenance engineers, and asked them to rate the factors and benefits. This study identified which factors were more important to state DOTs when assigning maintenance work to in-house staff or to private contractors. Statistical test results showed that the top two ranked factors influencing the selection of in-house (MBC and PBC) were availability of DOT staff and DOT staff have specific skills for jobs. Regarding the levels of satisfaction with benefits, on average, the respondents were significantly more satisfied with using in-house resources than with MBC or PBC methods. The study also determined the levels of satisfaction with quality of work that state DOTs and private contractors had with these methods.