Structure and Infrastructure Engineering


Impact factor 2.81

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Publications in this journal

  • Structure and Infrastructure Engineering 01/2015;
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    ABSTRACT: Water pipes are considered as tangible assets designed to provide a level of service throughout an expected lifetime. The asset can be characterised by two types of values: capital or accounting value and functional value. The capital value of assets depreciates according to a specific rate per time period. The depreciation is assessed by the annual amortisation of the capital asset, which constitutes a potential self-budgeting for future renewal. The development in the last 20 years of public sector accounting standards boards dedicated to tangible capital assets management has encouraged water and wastewater utilities to consider capital depreciation as a decision-making criterion for asset prioritisation. At the same time, when the capital depreciates the asset function deteriorates, but this deterioration is more difficult to assess. In fact, each asset can be evaluated according to a functional value that indicates the capacity of the asset to deliver the designated service at the required level. This value declines during the service life because of the occurrence of unexpected events (failures, breaks, leaks and degradation). The functional deterioration, also referred to as ‘obsolescence’ or ‘reliability’, is still misunderstood for water pipe assets. This study addresses the following questions: How can the functional value be estimated for water systems both at the pipe and at the network scale? How can the decision-making process for pipe renewal be improved by incorporating specific indicators based on both functional and accounting values? The current research focuses on the definition of an appropriate time-dependent functional value, based on the following hypothesis: the functional value depends on both structural and hydraulic deterioration of the pipe asset, but is partially restored by curative maintenance actions. The calibration of the functional value is mainly based on historical incident data, roughness data and managers' opinions. In order to carry out the decision-making process, the evolution of the functional value is simultaneously analysed with the depreciation of the capital asset value. The implementation of the approach at the pipe and the network level leads to an assessment of innovative criteria for the purpose of assessing possible renewal policies.
    Structure and Infrastructure Engineering 01/2015; 11(2):15.
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    ABSTRACT: In railway lines, transition zones between different track support conditions normally evidence higher degradation rates, thus requiring additional maintenance to ensure safety and service quality. Studies based on numerical simulations indicate that under sleeper pads (USP) can minimise those degradation rates. The study presented herein focuses on the influence of USP on the dynamic behaviour of transitions to underpasses, in an attempt to fill the gap between numerical and field studies. To that aim, the authors used finite element method models, calibrated and validated with field measurements. These models take into account the train–track interaction and include all relevant track components and backfill geomaterials. This study shows that soft USP have a significant influence over the track's dynamic behaviour: amplifying rail displacements and sleeper accelerations, and inducing abrupt variations in the track vertical stiffness and oscillations in train–track forces. To benefit from the use of USP, the authors highlight the need to carefully design stiffness properties of USP and determine their arrangement at transitions. An improved design for the transition zone is proposed.
    Structure and Infrastructure Engineering 12/2014;
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    ABSTRACT: A conceptual model for the prediction of the shear-flexural strength of slender reinforced concrete beams with and without transverse reinforcement is presented. The model incorporates the shear transferred by the un-cracked concrete chord, along the crack’s length, by the stirrups, if they are, and, in that case by the longitudinal reinforcement. After the development of the first branch of the critical shear crack, failure is considered to occur when the stresses at any point of the concrete compression chord reach the assumed biaxial stress failure envelope. A physical explanation is provided for the evolution of the shear transfer mechanisms, and the contribution of each one at ultimate limit state is formulated accordingly. Simple equations are derived for shear strength verification and for designing transverse reinforcement. The method is validated by comparing its predictions with the results of 1131 shear tests, obtaining very good results in terms of mean value and coefficient of variation. Because of its accuracy, simplicity and theoretical consistency, the proposed method is considered to be very useful for the practical design and assessment of concrete structures subjected to combined shear and bending.
    Structure and Infrastructure Engineering 10/2014;
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    ABSTRACT: In recent years, appraisal of the condition and rehabilitation of existing bridges has become an ongoing problem for bridge owners and administrators in all developed countries. Reliable methodologies are therefore needed in the assessment and retrofit design phases, to identify the vulnerability of each bridge class. The specific problems of common arch bridge types are discussed herein, for both reinforced concrete and masonry structures, proper interventions for their static and seismic retrofitting are illustrated and several examples of applications are provided. Retrofitting is usually coupled with functional refurbishment, according to a methodological approach that takes into account bridge characteristics, state of maintenance and functional requirements, and environmental aspects connected with repair and strengthening systems.
    Structure and Infrastructure Engineering 08/2014;
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    ABSTRACT: A life cycle costing system should include the key variables that drive future costs in order to provide a framework for reducing the risk of under- or overestimating the future costs for maintenance and rehabilitation activities. In Sweden, price of oil products is mostly affected by the global economy rather than by the national economy. Whereas the price index of oil products has had a high fluctuation in different time periods, the cost fluctuation related to labour and equipment has been steady and followed the consumer price index (CPI). Contribution of the oil products was shown to be more than 50% of the total costs regarding construction and rehabilitation of asphalt pavements in Sweden. Consequently, it was observed that neither Swedish road construction price index (Vägindex) nor CPI has properly reflected the price trend regarding the asphalt pavement construction at the project level. Therefore, in this study, a framework is suggested in which energy- and time-related costs are treated with different inflation indices in order to perform a better financial risk assessment regarding future costs.
    Structure and Infrastructure Engineering 01/2014; 10(12):1638-1647.
  • Structure and Infrastructure Engineering 01/2014;
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    ABSTRACT: In recent decades, research on the management of infrastructure assets has increased steadily. However, there are concerns raised about the contribution of studies to a coherent body of knowledge. There is a call for a more structured understanding of the knowledge that is emerging around the management of infrastructure assets. This paper attempts to answer this call through an empirical study based on the reference lists of over 8200 articles that present their study relevant to the management of infrastructure assets. In so doing, we apply recognised techniques from bibliometric and social network analyses to visualise and identify major and minor topics, where researchers have oriented and contributed. We find that managing infrastructure assets traditionally was object-oriented, such as pavements, bridges, water and utility networks, and that attention is only now emerging on the life-cycle decision-making and organisational aspects, although the latter remains weakly linked with technical aspects. We conclude with shared research orientations in ‘managing’ infrastructure assets.
    Structure and Infrastructure Engineering 10/2013;
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    ABSTRACT: The authors have been conducting a static continuous monitoring experiment to assess the validity of some damage detection algorithms, consisting in non-model-based statistical data processing, previously validated, even for small levels of damage, on numerically simulated 2D finite element models of simply supported and continuous beams. Tests have been conducted in Italy on two specimens of pre-stressed R.C. beams equipped with fibre optic strain sensors and temperature sensors and placed outdoor. During the tests, several events have been artificially produced: a ballast load has been positioned on the beams and various known levels of damage have been introduced. One of the two beams was kept intact for reference. Preliminary data processing has disclosed substantial differences between the numerical simulations and the measurements obtained on the field for the case of simply supported beams. This paper shows that environmental variations have a great effect on measurements and should be correctly removed from the strain time histories before a reliable damage detection procedure can be successfully applied.
    Structure and Infrastructure Engineering 02/2013;
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    ABSTRACT: This article presents the results of an analytical study on the structural behaviour of buried concrete-lined corrugated steel pipe (CLCSP). CLCSP combines the hydraulic characteristics of concrete pipe with an extended service life compared to unlined corrugated pipe. It is typically factory manufactured and shipped to the jobsite for roadway drainage applications. However, recent investigations have also demonstrated the ability to rehabilitate deteriorating metal culverts using a spray-on mortar lining approach. Since the primary intent of the concrete liner of manufactured CLCSP is to prevent abrasion and corrosion and improve the hydraulic performance, design guides for metal culverts lined with concrete have not been developed. A better understanding of the structural significance and the effect of the concrete lining on the strength of CLCSP is therefore needed. This study evaluated the structural effects of the concrete lining in CLCSP using finite element analysis and detailed soil modelling and proposes a design methodology for CLCSP.
    Structure and Infrastructure Engineering 02/2013; 9(2):130-140.
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    ABSTRACT: Cyclic response of a class of reinforced concrete bridges with different degrees of irregularity in longitudinal direction has been investigated. Eighteen bridge configurations have been identified from regular to the so-called highly irregular models. The geometric irregularity in this class of bridges is assumed to vary with the height of the piers. Using non-linear fibre-based analytical models, the cyclic response curves have been generated for theindividual piers of each of these 18 bridge models. Discussions have been made about the imposition of the displacement ductility demand of the piers versus the bridge regularity. Comparison of the cyclic response curves shows that the most vulnerable bridges are the irregular ones, and a high level of damage and ductility demand is expected for the short piers of this class of bridges.
    Structure and Infrastructure Engineering 01/2013; 9(2):161-171.
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    ABSTRACT: Since the mid-twentieth century, prestressed concrete (PC) bridges have been significantly developed to become the most important type of bridge in the world. However, only a few studies have dealt with the reliability-based design optimisation (RBDO) of PC bridges despite the fact that RBDO demonstrates the real behaviour of structures. Moreover, the corrosion of post-tensioned tendon in PC bridges seriously caused sudden failures which have been recorded in the world. Since then, this study presents the probabilistic model and approach to formulate and analyse the RBDO of PC box girder bridges which consider the pitting corrosion phenomenon of shear, torsion reinforcements and post-tensioned tendon. A practical example of a typical PC box girder bridge is presented and discussed. Sensitive analyses are performed to evaluate the influence of ultimate target reliability index on the optimal solution. For the simple support PC box girder bridge, the ultimate target reliability index should be in the range of βult: 3.5–5 in order to produce the optimal design.
    Structure and Infrastructure Engineering 01/2013; 9(1):78-96.