The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

Mark G Stewart - One of the best experts on this subject based on the ideXlab platform.

  • spatial time dependent reliability analysis of corroding pretensioned prestressed concrete Bridge Girders
    Structural Safety, 2007
    Co-Authors: Sigit M Darmawan, Mark G Stewart
    Abstract:

    Accelerated pitting corrosion tests have been performed to obtain spatial and temporal maximum pit-depth data for prestressing wires. This data is then used to develop probabilistic models of pitting corrosion and strength capacity of 7-wire strands. The probabilistic model of pitting corrosion for strands is then combined with a non-linear Finite Element Analysis and probabilistic models of corrosion initiation and propagation to study the spatial and temporal effects of pitting corrosion on a typical pretensioned prestressed concrete Bridge Girder. The limit states considered are flexural strength and serviceability. The spatial time-dependent reliability analysis takes into account the uncertainties and variabilities related to material properties, dimensions, loads and corrosion parameters as well as the spatial variability of pitting corrosion of prestressing strands. Including the spatial variability of pitting corrosion in the reliability analysis increased both the probability of strength and serviceability failure when compared with a mid-span sectional analysis.

  • Effect of spatially variable pitting corrosion on structural reliability of prestressed concrete Bridge Girders
    Australian Journal of Structural Engineering, 2006
    Co-Authors: M. S. Darmawan, Mark G Stewart
    Abstract:

    AbstractAccelerated pitting corrosion tests have been performed to obtain maximum pit- depth data for prestressing 7-wire strands. This data is then used to develop probabilistic models of pitting corrosion and strand strength capacity. The probabilistic model of pitting corrosion is incorporated in a non-linear Finite Element Analysis to study the spatial and temporal effects of pitting corrosion on a typical pretensioned prestressed concrete Bridge Girder. The limit states considered are flexural strength and serviceability. The spatial time-dependent reliability analysis takes into account the uncertainties and variabilities related to material properties, dimensions, loads as well as the spatial variability of pitting corrosion of prestressing strands. Including the spatial variability of pitting corrosion in the reliability analysis increased both the probability of strength and serviceability failure when compared with a mid-span sectional analysis.

Yoko Okazaki - One of the best experts on this subject based on the ideXlab platform.

  • Improvement of aerodynamic stability of suspension Bridges with H-shaped simplified stiffening Girder
    Frontiers of Structural and Civil Engineering, 2016
    Co-Authors: Hiroshi Katsuchi, Hitoshi Yamada, Mayuko Nishio, Yoko Okazaki
    Abstract:

    Wind-tunnel study on the improvement of aerodynamic stability of simplified suspension-Bridge Girder structures was conducted with using a 1/40-scaled section model. Objective of the study is the development of an economically superior suspension Bridge with 500–1,000 m center span length. The wind-tunnel test showed that an edge-Girder type cross section exhibited large amplitude torsional vortex-induced vibration as well as torsional flutter at a low wind speed. Accordingly, aerodynamic countermeasures of open grating deck and triangular faring, and structural countermeasures of center stay, diagonal bracing and mass increase were tried to improve the aerodynamic stability. Finally, feasibility of the best combination to a full-scale Bridge was examined by structural analysis.

Masoud Motavalli - One of the best experts on this subject based on the ideXlab platform.

  • prestressed cfrp strips for concrete Bridge Girder retrofitting application and static loading test
    Journal of Bridge Engineering, 2016
    Co-Authors: Julien Michels, Christoph Czaderski, Michal Staśkiewicz, Renata Kotynia, Yunus Emre Harmanci, Masoud Motavalli
    Abstract:

    AbstractThis paper presents an investigation on the practicability and structural efficiency of prestressed carbon-fiber–reinforced polymer (CFRP) strips with a gradient anchorage in the framework of a Bridge-strengthening application in Poland. The nonmechanical anchorage system avoids the installation of metallic bolts and plates, with the exception of a temporary support frame. Two 18.4-m-long large-scale prestressed concrete Girders were produced following the drawings of the existing Bridge construction. One Girder served as a reference, and the second one was strengthened with two prestressed CFRP strips. In this case, the initial negative cambering was leveled out by a layer of dry shotcrete. CFRP strips with a prestrain of 0.58% were applied for flexural upgrading. Both Girders with a total length of 18.4 m were finally statically loaded up to failure to assess the strengthening efficiency in flexure of the retrofitting technique used. Tensile failure of the CFRP strips was reached, indicating an ...

  • prestressed cfrp for strengthening of reinforced concrete structures recent developments at empa switzerland
    Journal of Composites for Construction, 2011
    Co-Authors: Christoph Czaderski, Masoud Motavalli, Kerstin Pfyllang
    Abstract:

    In civil engineering today, only 20 to 30% of the strength of carbon-fiber-reinforced polymer (CFRP) strips is used when they are applied as externally bonded strips for flexural and shear strengthening or in confinement of reinforced concrete (RC) structural elements. The strips are better used when the CFRP material is prestressed. This offers several advantages, including reduced crack widths, reduced deflections, reduced stress in the internal steel, and possibly increased fatigue resistance. In this paper, recent developments in the field of RC strengthening using prestressed CFRP are presented. The paper focuses on developments in flexural and shear strengthening and column confinement made at the Swiss Federal Laboratory for Materials Testing and Research (Empa). Several innovative ideas have been successfully realized in the laboratory. For example, a gradient prestressing technique without end anchorage plates was developed and successfully applied to a 17 m RC Bridge Girder. A confinement techni...

  • determining the remaining tendon force of a large scale 38 year old prestressed concrete Bridge Girder
    Pci Journal, 2006
    Co-Authors: Christoph Czaderski, Masoud Motavalli
    Abstract:

    A reliable method to determine the remaining prestressing force is often needed in routine inspection of Bridges, during rehabilitation of structures, or when retrofitting for increased vehicle capacity. This article reports on a study that was undertaken to determine the remaining tendon force of a large-scale (17 meters long), 38-year-old prestressed concrete Bridge Girder. The authors used a semi-destructive test method and compare measurements of the prestressing force losses determined by their method with calculations methods based on fib guidelines and Swiss code. They found that calculated and measured prestressing force losses were generally in good agreement. A long-term prestressing force loss of about 20% was determined. The authors conclude that their material tests on the prestressing steel showed that 38 years of constant stress had no discernable effect on its tensile strength. This article reports on the first part of an extensive test program that will be carried out on five similar test beams.

Hiroshi Katsuchi - One of the best experts on this subject based on the ideXlab platform.

  • Improvement of aerodynamic stability of suspension Bridges with H-shaped simplified stiffening Girder
    Frontiers of Structural and Civil Engineering, 2016
    Co-Authors: Hiroshi Katsuchi, Hitoshi Yamada, Mayuko Nishio, Yoko Okazaki
    Abstract:

    Wind-tunnel study on the improvement of aerodynamic stability of simplified suspension-Bridge Girder structures was conducted with using a 1/40-scaled section model. Objective of the study is the development of an economically superior suspension Bridge with 500–1,000 m center span length. The wind-tunnel test showed that an edge-Girder type cross section exhibited large amplitude torsional vortex-induced vibration as well as torsional flutter at a low wind speed. Accordingly, aerodynamic countermeasures of open grating deck and triangular faring, and structural countermeasures of center stay, diagonal bracing and mass increase were tried to improve the aerodynamic stability. Finally, feasibility of the best combination to a full-scale Bridge was examined by structural analysis.

Lech Wlasak - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Study on Static and Dynamic Performance of a Novel GFRP Bridge Girder
    Composite Structures, 1
    Co-Authors: Tomasz Siwowski, Mateusz Rajchel, Lech Wlasak
    Abstract:

    Abstract A novel glass fibre-reinforced polymer (GFRP) Bridge Girder was developed and implemented in a Bridge superstructure as the result of the domestic R&D project. The novel GFRP Girder consists of a shell with trapezoidal cross-section and a sandwich deck slab, both acting compositely owing to structural bonding. Before superstructure implementation, a test specimen fabricated as a full-scale prototype of the GFRP Bridge Girder was subjected to a series of static and dynamic tests to evaluate its structural performance and to verify design predictions and to check relevant code requirements. This paper presents a prototype GFRP Girder itself and the selected results of an experimental study on its stiffness, strength, ultimate capacity and failure mode, global factors of safety against failure and dynamic characteristics. The output of testing confirmed that the proposed GFRP Bridge Girder has an appropriate structural performance and fulfils the design assumptions and relevant standard requirements to be considered in an actual road Bridge design.