Now showing 1 - 6 of 6
  • Publication
    Variations of safety factors for bridges over their lifetime considering changing live load definitions
    Design of long lasting structures would require insights from the past. In this regard, design of future long-life bridges and the assessment of current ageing bridges can particularly benefit from understanding the evolution of safety over lifetime. This is an important issue since there has been an evolution of design live loads over the lifetime of such bridges in the past and such changes in definition can influence the computed estimates of safety; while the true state of the structure remains the function of the site-specific live loads. Considering the limitations around instrumenting individual bridges, it is important to investigate the variations of such computed estimates over their lifetime. Previous studies around this problem have focused on the changes in terms of reliability indices over time and life-cycle costs due to degradation. However, the key change in safety estimates for owners of bridges based on changes in live load definitions will be reflected in terms of safety factors, which remain a key index for taking commercial and safety intervention decisions for a bridge stock. This paper presents the variation in safety factors of representative slab, beam and prestressed bridges for changing live load definitions and compares it with corresponding changes in reliability index parameter importance factors for the life-cycle of such bridges. The work provides an insight to how future changes in anticipated changes in live loading definitions can influence safety factors and provides guidance around better built bridges for the future.
      173
  • Publication
    Effects of increasing design traffic load on performance and life-cycle cost of bridges
    (CRC Press - Taylor & Francis Group, 2016-06-07) ; ; ;
    Due to the onerous and expensive nature of preventative and essential maintenance of existing bridge infrastructure, it is prudent to look into methods of improving life-cycle safety and cost of newly constructed bridges at the design phase. In an effort to achieve economy in material quantities and initial cost, the structural capacity of these bridges is often at the required minimum target level. This paper investigates the effects that increased design traffic loading have on the initial construction cost and whether that could be balanced by a reduced requirement for financial intervention in the mid to later stages of the bridge’s design-life. This is achieved by conducting a life-cycle performance and cost assessment on a reinforced concrete slab bridge that is designed to increasing standard traffic loads.
      153
  • Publication
    Reliability analysis of a bridge network in Ireland
    (ICE Publishing, 2016-03-01) ;
    This paper presents the reliability analysis of a network of six bridges in Ireland, with a focus on the sensitivity analysis and the analysis of parameter importance measures. The basis of the analysis stems from the possibility of investigating similarities in various parameters, leading to the establishment of network-level indicators based on fully probabilistic assessments. Initially, deterministic assessments are carried out on these bridges to verify the limit states, and a detailed probabilistic analysis is conducted, taking uncertainty in relation to the available information into account. Parametric importance measures are established across the network, and patterns identified from these studies suggest the potential for reliability-based network calibrations of bridge structures. This paper is expected to encourage a greater sharing of network-level information of the owners and managers of bridges.
      290Scopus© Citations 6
  • Publication
    Cross-asset management for road infrastructure networks
    Limitation of resources and variations of interest or priority of different stakeholders of road infrastructure networks often lead to multiple considerations of intervention options. It is of interest to identify the best available intervention or investment option under a multi-criteria framework. Markers of performance may be varied and the approach towards maintenance management may have different philosophies based on specific organisational structures of governance. This paper presents a methodology for cross-asset management that caters to different maintenance management systems without modification. Optimisation approaches and effective implementation methods are identified. Practical implementation guidelines of the developed framework are illustrated.
      445Scopus© Citations 10
  • Publication
    Reliability index and parameter importance for bridge traffic loading definition changes
    With the continued evolution of traffic loading specifications, safety classifications of bridge structures are subject to change, independent of the actual condition of the structures at that point in time. As investment decisions are often based on these safety classifications, a reclassification of safety level due to changing of traffic load definitions can lead to misinterpretation of the actual state of the structure, and thus lead to a misallocation of resources. Should a reclassification of safety occur after a change in traffic load specification, the question as to whether modern design codes are producing more or less robust bridges than previous design codes is raised. To investigate this, three bridge structures were assessed for evolving definitions of traffic load. Using deterministic and probabilistic methods, critical limit states were assessed and the associated reliability indices and parametric sensitivity factors were determined and compared across various code specifications. This comparison allowed for an evaluation of how the evolution of traffic load over time influences the computed safety of bridge structures.
      393Scopus© Citations 5
  • Publication
    Reliability index and parameter importance for bridge traffic loading definition changes
    With the continued evolution of traffic loading specifications, safety classifications of bridge structures are subject to change, independent of the actual condition of the structures at that point in time. As investment decisions are often based on these safety classifications, a reclassification of safety level due to changing of traffic load definitions can lead to misinterpretation of the actual state of the structure, and thus lead to a misallocation of resources. Should a reclassification of safety occur after a change in traffic load specification, the question as to whether modern design codes are producing more or less robust bridges than previous design codes is raised. To investigate this, three bridge structures were assessed for evolving definitions of traffic load. Using deterministic and probabilistic methods, critical limit-states were assessed and the associated reliability indices and parametric sensitivity factors were determined and compared across various code specifications. This comparison allowed for the evaluation as to how the evolution of traffic load over time influences the computed safety of bridge structures.
      309Scopus© Citations 5