Effects of Cyclic Loading on Structural Performance of Glass FRP Reinforced Concrete Elements - PowerPoint PPT Presentation

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Effects of Cyclic Loading on Structural Performance of Glass FRP Reinforced Concrete Elements

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Title: Effects of Cyclic Loading on Structural Performance of Glass FRP Reinforced Concrete Elements


1
  • Effects of Cyclic Loading on Structural
    Performance of Glass FRP Reinforced Concrete
    Elements
  • Francisco Aguíñiga
  • Hector Estrada
  • Jorge Cruz
  • Civil and Architectural Engineering Program
  • Texas AM University Kingsville
  • Department of Civil Engineering
  • Universidad Michoacana de San Nicolas de Hidalgo

2
Problem corrosion of steel
  • Causes important deterioration on bridge decks
    by the use of deicing salts
  • Solution?
  • Use FRP bars

3
Application
  • Sierrita de La Cruz creek Bridge Amarillo, Texas

4
Question
  • Would overhang bars break due to fatigue?
  • Bars on overhang would be loaded to approximately
    20 of ultimate load during service conditions
    (AASHTO wheel loading 1ft from railing)
  • Design would be governed by either deflections or
    cracking shear
  • Experiment
  • Design specimens to replicate geometry and field
    load conditions study flexural performance

5
Materials
  • FRP bars
  • Concrete
  • Design strength
  • fc 27.6 MPa
  • Actual strength
  • fcr 47.6 MPa

6
Beams
  • Study influence of
  • Bar diameter (13 and 19 mm)
  • Bar type (P, V1, or V2)
  • Concrete cover (38 and 51 mm)
  • All beams aged in the field for 1 year
  • 12 beams loaded to failure at constant load rate
    control
  • 13 beams subjected to 2 million cycles of loading
    at f10 Hz

7
Beam geometry
8
Loading setup
9
Constant load rate results
  • Beams with 13 mm diameter bar

10
Constant load rate results
  • Beams with 19 mm diameter bar

11
Cyclic load specimens
  • Bar stress at midspan

12
Comparison of results
  • Failure loads with and w/o cyclic loading for 13
    mm diam. bar specimens

13
Comparison of results
  • Failure loads with and w/o cyclic loading for 19
    mm diam. bar specimens

14
Conclusions
  • Surface finish, concrete cover, and bar diameter
    do not significantly affect the ultimate flexural
    capacity of GFRP reinforced concrete beams under
    cyclic loading
  • The residual flexural strength of GFRP reinforced
    concrete beams is not affected by applying cyclic
    loading to bar stresses of approximately 21
    percent of the average GFRP bar strength

15
Conclusions
  • One specimen survived nearly 5 million cycles of
    loading and retained 100 of its flexural strength

16
Conclusions
  • These results although based on limited data may
    give a good indication of the performance of a
    bridge overhang
  • Considering that the design strength was obtained
    using the loading specified by AASHTO (wheel load
    applied 1 ft from face of railing)
  • During service conditions vehicles typically do
    not drive so close to the railing
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