Efficiency Of Using Steel End Caps In Improving The Post-Fire Flexural Behavior Of Frp Reinforced Concrete Beams
The use of Fiber Reinforced Polymer (FRP) bars as an alternative to traditional steel reinforcement helps overcoming durability problems in reinforced concrete structures. The behavior of FRP-RC structures is satisfactory at only low temperatures, hence the application of combustible FRP material...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2017
|
| Subjects: | |
| Online Access: | http://eprints.usm.my/45761/1/Efficiency%20Of%20Using%20Steel%20End%20Caps%20In%20Improving%20The%20Post-Fire%20Flexural%20Behavior%20Of%20Frp%20Reinforced%20Concrete%20Beams.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The use of Fiber Reinforced Polymer (FRP) bars as an alternative to traditional steel
reinforcement helps overcoming durability problems in reinforced concrete structures.
The behavior of FRP-RC structures is satisfactory at only low temperatures, hence the
application of combustible FRP materials in commercial, industrial and residential
buildings, where the possibility of fire occurrence is relatively high, can be dangerous.
Further research to evaluate and enhance the performance of FRP-RC structures under
fire conditions is required. In this study, the effect of high temperatures on the
mechanical properties of FRP/Steel bars, bond behavior between FRP/Steel bars and
concrete, and the flexural response of concrete beams with different types of FRP bar
reinforcement was investigated in much details. A new steel-end-caps technique was
proposed aiming to improve anchorage of embedded FRP bars in concrete. For that
FRP/Steel bars, plain concrete, pullout and beam specimens (with and without steel
end caps) were prepared and then cured for 28 days and later tested before and after
subjected to elevated temperatures of up to 500°C. Concrete and FRP bars suffered
significant reductions in their mechanical properties due to exposure to high
temperatures. Bond strength between FRP bars and concrete had decreased upon
exposure to temperature in the range of 125 to 325°C, with the reduction reaching as
high as 85%. These reductions were reflected negatively in the behavior of heated
FRP-RC beams hence cracking load, ultimate load capacity, stiffness and total
absorbed energy were reduced by as high as 89%, 81%, 79%, and 70%, respectively
whereas mid-span deflections and ductility indices were increased noticeably by as
high as 50% and 94%, respectively. Attaching steel end caps to the ends of FRP bars
had improved their bond strength with concrete before and after exposure to high
temperatures of up to 325oC. Consequently, the flexural performance of FRP-RC
beams with end-cap anchorage was improved where the cracking load, ultimate load
capacity, stiffness, deflection at ultimate load, and total absorbed energy were
increased to reach as high as (124%, 208%, 225%, 196%, and 453%) and (33%, 123%,
58%, 216% and 215%) before and after heating up to 500°C, respectively, compared
with that of control beams without end anchorage. Based on the experimental results,
an analytical model was proposed to predict the behavior of the ascending part of bondslip
relation between the different FRP bars and concrete under high temperatures.
Another theoretical method was also proposed to predict the theoretical ultimate load
capacity of FRP-RC beams. The predictions of the two models were in an excellent
agreement with the experimental results. |
|---|