Biaxial bending interaction diagrams

Biaxial bending interaction diagrams for reinforced concrete column design

solution

The steps to calculate biaxial flexural strength of a rectangular reinforced concrete column for a given nominal axial strength and moment ratio of biaxial bending moments are as follows:

1. assuming a value for the angle of the neutral axis (a) and the neutral axis depth (c) to calculate the strain values in each reinforcement layer

2. Calculate the forces values in the concrete (Cc) and reinforcement layers (Fst)

3. Calculate Pn, Mnx/Mny using the following equations


the procedure above should be repeated until the calculated Pn, and Mnx / Mny are euqal to the given Pn, and Mnx/Mny.

The following figure demonstrates the procedure explained above:

출처: Biaxial Bending Interaction Diagrams for Rectangular Reinforced Concrete Column Design (ACI 318-19) Structure Point






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Punching shear resistance of slabs and column bases without shear reinforcement(KDS vs EC2)

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 KDS 24 14 21 콘크리트교 설계기준(한계상태설계법) 4.1.4.3 전단철근이 없는 슬래브 또는 기둥 기초판의 뚫림전단강도 식(4.1-46), 식(4.1-47)에서 다음 그림과 같이 괄호안의 100은 없어야 한다. 극한하중조합에서 콘크리트 재료계수 0.65이므로 (표 1.4-1 재료계수) 0.85*0.65 = 0.5525 극단상황하중조합에서 콘크리트 재료계수 1.0 0.85*1.0 = 0.85 EuroCode2  6.4.4 Punching shear resistance of slabs and column bases without shear reinforcement C_ ʀd.c = 0.18 /  γc Persistent & Transient Partial factor for concrete 1.5 1/γc = 1/1.5 = 0.667 0.18 * 100^(1/3) = 0.835 C_ ʀd.c * 10^(1/3) =  0.18 /  γc * 100^(1/3) 0.18/1.5 * 100^(1/3) = 0.557 Accidental Partial factor for concrete 1.2 1/1.2 = 0.833 0.18 * 100^(1/3) = 0.835 C_ ʀd.c * 10^(1/3) =  0.18 /  γc * 100^(1/3) 0.18/1.2 * 100^(1/3) = 0.696 KDS24 와  EC2의 뚫림전단 강도 비교
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