Journal of Performance of Constructed Facilities

This paper presents a classification system for the inspection, diagnosis, and rehabilitation of vinyl and linoleum floorings in healthcare infrastructures. First, the identification of the main anomalies affecting these floorings and their probable causes is made. The adequate corresponding in situ diagnosis methods and rehabilitation techniques are also analyzed. Then, correlation matrices are created, namely: anomalies-causes; interanomalies; anomalies-diagnosis methods; and anomalies-repair techniques. An inspections program was carried out on 101 floorings in six health infrastructures. With the results obtained in the inspection program, the proposed theoretical system was validated through a statistical analysis. From this validation, anomaly sheets, diagnosis method sheets, and repair technique sheets were obtained. The classification systems, including the correlation matrices, were also validated. The proposed innovative vinyl and linoleum floorings inspection system intends to help inspectors to standardize their procedures. To the best of the authors’ knowledge, there is no similar system to support the inspection and diagnosis of vinyl and linoleum floorings.

The large-scale management and monitoring of existing buildings is a complex issue for the holders and administrators that are responsible for user safety. Decision support systems (DSS) can be used to simplify such operations and to detect the criticalities that can compromise human safety or building usability. This paper proposes a DSS designed for detecting building criticalities, which includes a software application (APP) implemented on mobile devices and a web service–based quality detection platform (QDP) that stores and processes data. The APP allows the building users to report criticality through photographic inspection and to answer a suitable questionnaire. The collected data are processed by the QDP, which quantifies critical issues through a set of key performance indices (KPIs). The KPI formulations are computed by an optimized analytic hierarchy process (O-AHP), which is a modified version of the AHP. The DSS allows monitoring buildings at the regional scale and provides a classification of the most damaged buildings, which is useful for civil protection aims and for the prioritization of interventions.

The seismic performance of bridge structures is significantly affected by their column height, design era, and horizontal deck curvature. However, existing risk assessment platforms do not appropriately account for the effect of column height and horizontal deck curvature. This paper investigates the effect of column height, design era, and deck curvature on probabilistic seismic demand models and fragilities of bridges. This paper selects a typical configuration of horizontally curved concrete box-girder bridges in California: two-frame five-span bridges with single-column bents. Extensive nonlinear time history analysis results for the bridges including the uncertainties are initially compared using a statistical technique, analysis of covariance. Results from the analysis of covariance are used to estimate the influence of column height, design era, and horizontal deck curvature on bridge performance. An increase in the deck horizontal curvature is found to increase the bridge vulnerability irrespective of the design era and height range. Although the seismic vulnerability of bridges constructed prior to 1970 increases with the increase in the column height, there is no specific trend in the change in vulnerability with respect to column height for bridges constructed after 1970. This research also shows that the implementation of seismic design principles reduces the seismic vulnerability of the bridges.

The service life of adjacent box beam bridges is curtailed by the corrosion of reinforcement in the girders and spalling of concrete. This damage is attributed primarily to infiltration of water and chemical agents through longitudinal cracks in the shear keys. However, there are two other possible factors that can lead to water penetration of the bridge structure and eventual failure in box beam bridges: nonuniform box beam dimensions and bridge transverse slope. No study has been conducted to evaluate the effects of these two factors on induced stresses in adjacent box beam bridges. Typically, box girders are placed together with a transverse slope to facilitate drainage, which creates contact areas along just the bottom edges of adjacent girders. Additionally, for girders with nonuniform dimensions, even if within beam dimension tolerance, the contact between adjacent beams may be created at isolated spots. Measurements made at a box beam fabrication site verified inconsistency of beam dimensions. Three-dimensional finite-element models of composite and noncomposite single-span skew-adjacent box beam bridges were created to determine the stresses induce at the contact areas under environmental load conditions. The finite-element model was calibrated and validated in terms of the stresses in tie bars using experimental temperature profiles (uniform with and without temperature gradient). Two models were analyzed; the first model represented the contact areas generated due to drainage slope and the second one represented nonuniform beam dimensions using realistic input data. Under uniform and temperature gradient conditions, the models showed that contact stresses exceeded the concrete design strength at certain spots along the beams’ length. For girders with full flat contact, the contact stresses were noted to be less than the concrete strength. Additionally, the results of the analysis showed the contact stresses were reduced when modeling a bridge with a reinforced concrete deck. Moreover, the skew geometry showed a significant effect on the distribution of stresses at contact zones. Furthermore, the finite-element failure mode was compared with past research in terms of the locations of the greatest deterioration, and good agreement was found. Based on the results, it is recommended in this study to construct box beam bridges with enough spacing between the beams to ensure that no contact occurs between them; it is also recommended to manufacture box beams with high levels of accuracy.

The total water needs of the city of Athens are supplied through the Mornos aqueduct. The Mornos aqueduct includes series of tunnels, siphons, and open R/C (reinforced concrete) canal segments. On the 29th of March 2011, sudden failure of the Mornos aqueduct took place causing interruption of the water supply. The failure has occurred in the Taxiarches canal of the Mornos aqueduct. It resulted in failure and displacement of the segmental parts of the aqueduct in a region spanning 80 m. The failure of the canal occurred in a zone of sharp morphology, at the front of an overthrust, vulnerable to erosion. A numerical investigation was carried in an effort to interpret the mechanism that caused the failure. The soil–structure interaction of the foundation conditions in respect to the segmental superstructure of the aqueduct is studied utilizing numerical simulation tools. The finite-element numerical analysis that was carried out includes two research fields. Initially, the role of the joint interface between articulated segments was investigated. Subsequently, the behavior of the whole numerical simulation of the aqueduct including the joint interfaces between segments were studied. Different numerical analysis was carried out to evaluate numerically the failure scenario. It was numerically established that the high water level in the surveillance road next to the aqueduct and the nonuniform subsoil condition of the foundation of the aqueduct raised the vulnerability of the structure. The numerical simulation proposed in the current study could be a useful tool for the inspection of articulated open channels for the avoidance of activation of similar failure mechanisms.

Pipelines are lifeline structures, as any significant disruption to the performance of these systems often translates into undesirable impacts on the economics and the living conditions of citizens. It is important to maintain the integrity of pipelines during severe natural hazards such as earthquakes. Prior observations have indicated that pipelines are highly vulnerable to earthquakes, and therefore the seismic behavior of pipelines has attracted great attention from researchers over the years. This paper presents a detailed review of the response of pipelines in previous major earthquakes with an emphasis on various seismic hazards, associated failure modes, and extent of pipeline failures in the last 110 years (1906–2016). In addition, the paper draws attention to the lessons learnt from the earthquakes that led to the development of seismic design criteria for pipelines. A state-of-the-art review on seismic fragility estimation for buried pipelines is presented along with a comparative study of existing fragility formulations. Also, the paper presents a brief review of different seismic mitigation techniques used in practice. Based on the review, areas of concern are identified, and the future direction for research is highlighted.

This paper is motivated by the experience of measurement and characterization of tunnel lining defects occurring in a real case involving four tunnels excavated by tunnel boring machines (TBMs). This experience has shown that often the causes of these defects were not well understood and not well covered by current design practices. The paper focuses on five defect types: uncontrolled cracking of the lining, ovalization, joint openings, misalignments, and edge ruptures. It is found that deficient gap filling is the cause of excessive cracking, ovalization and joint openings, whereas misalignments and edge ruptures are caused by deficient placing of the segments. Edge ruptures could also be related to lack of confinement of the stresses at the joint section in the longitudinal direction. The possibility of deficient gap filling is not contemplated in design practices, and perhaps it should be considered, in terms of having enough minimum reinforcement to control cracking when no significant axial force is present. Ovalization is interpreted as being caused by service loads, whereas in fact this paper shows that it is also due to deficient gap filling and its structural consequences are, therefore, not significant. The experience recounted in this paper is a good instance of the importance of understanding the underlying causes of the observed phenomena to properly treat them.

Seepage is always expected in earthen dams because they are made of porous materials. However, it should be always under control and its amount and pore-water pressures should be kept below acceptable limits. This can be satisfied by installing internal drains. This study reviews the characteristics of blanket, chimney, and toe drains and assesses their suitability and effectiveness for various material types and geometric characteristics in separate cases. Numerical simulations are conducted for steady-state seepage through a homogeneous and simple zoned earthen dam using the finite-element method. It is found that the seepage rate increases and the phreatic line shortens with an increase in the blanket drain length; the phreatic line becomes steeper within the core if the chimney drain material is relatively coarse; and the seepage rate becomes higher when the height of the toe drain is increased. The thickness of the blanket drain and the material gradation of the toe drain are found ineffective in the seepage behavior of the dams considered.

Antiliquefaction performance improvement for developed sites beneath existing structures has drawn increasing public attention to meet stricter requirements of seismic protection. Liquefaction mitigation using nanoparticles is a novel countermeasure because of its low environmental disturbance and greater environmental friendliness. This paper reports a centrifuge test to evaluate the effectiveness of laponite (the representative nanoparticle) for liquefaction mitigation. A constructed reservoir embankment foundation was selected as the prototype and the laponite-treated model was carried out with a centrifugal acceleration of $45g$. Additionally, the viscosity of laponite suspensions was measured to determine the appropriate concentration range and curing time. A similar test with an untreated model was conducted beforehand as a comparison. The subsequent research results showed that the generation of excess porewater pressure was suppressed and both lateral displacements and settlement were reduced in the laponite-treated model versus the untreated model. This paper provides experimental data beyond the elemental scale to support the beneficial effects of laponite on the antiliquefaction performance improvement of the developed sites.