Now showing 1 - 3 of 3
  • 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.
  • 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.
  • Publication
    The Influence of Flexible Towers on the Dynamics of Offshore Wind Turbine Gravity Base Structures
    With offshore wind turbines increasing in size, there is increasing interest in non-traditional support structures. New concepts include lightweight and flexible fiberglass composite towers that have potential benefits over traditional stiff steel towers. The aim of this paper was to assess how the combination of a more flexible wind turbine tower with an offshore concrete gravity base foundation would affect the dynamic response of the structure. The results focus on how the dynamic amplification factors (DAFs) change with varying levels of foundation stiffness during an extreme event (50 year return period extreme event).