High Performance Fiber Reinforced Concrete In Earthquake-resistant Construction

The advantages of using work-hardening, high-performance fiber reinforced concrete (HPFRC) in critical areas of earthquake resistant structures are increasingly recognized. Due to their ductile behavior HPFRCs is particularly attractive for use in areas where a large inelastic deformation capacity is needed to withstand the demands caused by a severe earthquake. Test results showed that HPFRCs serve as a substitute for specific details of seismic reinforcement by providing additional shear strength and confinement, which could lead to important simplifications in the construction of earthquake resistant structures.

In 1987, Naaman proposes to classify the fiber reinforced concrete is based on the tensile behavior after cracking (Fig. 1). When the rate of hardening behavior has been observed, the mixture is classified as high-performance fiber reinforced cement (HPFRC). When the strain softening behavior is observed, the mixture is classified as a simple fiber reinforced concrete (FRC).

After the first crack occurs HPFRC subjected to direct tension, the fibers bridge the crack to carry a greater load, thus increasing the composite cracking. This cracking process, which eventually leads to a dense mass of fine cracks, damage continues to locate the (substantial removal of the fiber) is one or a few cracks, traction typically between 0.5 and 3%. FRC on a regular basis, on the other hand, because the fibers can not carry more load after cracking, the location of damage will start as soon as the first structural cracking occurs.

The fibers also increase the compression behavior of concrete, especially by increasing the voltage on capacity. HPFRCs has shown to exhibit a very similar behavior in the confined concrete, load capacity exceeding 1%. This suggests that the confinement reinforcement relaxations are possible when using HPFRCs than concrete.

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What Is Fiber Reinforced Polymer (FRP) Rebar?

Reinforced concrete is a very common building material for construction of facilities and structures. Complementing the strength of concrete in tension is very limited, the construction of steel structure was a cost effective solution. However, insufficient concrete cover, poor design or workmanship, and the presence of large amounts of aggressive agents, including all environmental factors can lead to cracking of concrete and corrosion of steel bars. For example, the United States, almost 40% of bridges are structurally deficient or functionally obsolete, and the percentage is increasing, according to the Federal Highway Administration (Griffiths 2000) For many years there have been many studies on this subject the corrosion, and the interest of FRP (Fiber Reinforced Polymer) has recently emerged as a potential substitute for steel. A careful examination of the potential of FRP reinforcing bars to meet cost and performance may propose appropriate solutions.

The benefits

* Waterproof to chloride ions and chemical attack

* Tensile strength than steel

* 1/4th weight of steel reinforcement

* Transparent to magnetic fields and radio frequency

* Electrically and thermally conductive

Based on the above characteristics, FRP bars appears to be a promising alternative to steel reinforcement in concrete structures such as marine structures, parking structures, bridges, roads in extreme environments, and structures are very sensitive to magnetic fields and corrosion.

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