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Title |
A Study on the Flexural Minimum Reinforcement for Prevention of Brittle Failure Specified in KCI and EN Codes
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DOI |
https://doi.org/10.4334/JKCI.2014.26.2.211 |
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Keywords |
최소철근량 ; 휨강도 ; 연성지수 ; 파괴에너지 minimum reinforcement ; flexural capacity ; ductility index ; fracture energy |
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Abstract |
In the design of reinforced rectangular concrete beam structure, the minimum amount of flexural reinforcement is required to avoid brittle failure. KCI code is based on concept of ultimate strength and usually used as a model code. But bridge design code enacted by Ministry of land, transportation and maritime affairs in 2012 is based on concept of limit state and similar to Euro code EN 1992-2. This means that the minimum reinforcement presented in both design codes has different origination and safety margin. When rectangular concrete beams with minimum reinforcement are designed according to EN and KCI codes, the amount of minimum reinforcement specified in EN code is only 76% of that in KCI code. This makes the design engineers to be confused. In this study, flexural tests were conducted on nine beams with the two different minimum reinforcement specified in KCI and EN design codes. In results, the measured ratios of nominal strength to crack strength from the test were about 25% greater than those evaluated from the equations presented in KCI and EN codes. The EN beams having only 76% of the minimum reinforcement for the KCI beams were fractured by rupture of steel reinforcement but in ductile manner. It is confirmed that the minimum reinforcement concrete beams designed according to both codes have enough safety margin in flexural capacity and moreover in ductility.
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