The condition that columns are stronger than beams is automatically controlled according to Equation 7.3 .
Equation 7.3 is applied separately for each earthquake direction and for both directions of the earthquake, giving an unfavorable result.
All of the columns joining the node point N d ≤ 0.10 A c f ck are automatically controlled.
A c = Cross-sectional area of the column
f ck = Characteristic compressive strength of concrete
f cd = Design compressive strength of concrete
f yd = Design yield strength of longitudinal reinforcement
M ra = Bearing strength calculated according to f cd and f yd at the lower end of the free height of the column or wall torque
M r = column or in the upper end of the free height of the curtain for CDs and f yd 'calculated according to the ultimate moment
M r = Moment of positive or negative bearing capacity calculated according to f cd and f yd on the column or wall face at the left end of the beam
M rj = Negative calculated according to f cd and f yd on the column or wall face at the right end of the beam j positive bearing strength moment
N d = Axial force calculated under the combined effect of vertical loads and earthquake loads multiplied by the load factors.
V ik = Sum of shear forces calculated in the direction of the earthquake in all columns on the i'th floor of the building
V is =The sum of shear forces calculated in the direction of the earthquake considered in the columns where (M ra + M rü ) ≥ 1.2 (M ri + M rj ) is provided at both the lower and upper joints of the building. At the ends of the columns meeting the condition N d ≤ 0.10 A c f ck , Eq. Even if (7.3) is not provided, these columns are also not taken into account in the calculation of V is .
Conditions for Columns to be Stronger than Beams (Strong columns)
The sum of the moments of bearing strength of the columns is considered to be 20% more than the moments of the beams for both directions of the earthquake (Equation 7.3).
( M ra + M rü ) ≥ 1.2 ( M ri + M rj ) (7.3)
However, whether Equation 7.3 is fulfilled is exempted for the following conditions:
If N d ≤ 0.10 Ac f ck is achieved in both columns joining the node point
In single-storey buildings and at the nodes of columns that do not continue to the upper floor of multi-storey buildings
In case the curtain where the beams are stuck working like a column in the weak direction
It is considered to be stronger than column beams when equation 7.3 is satisfied or when the exemption conditions are met.
The situation that the columns are not stronger than the beams (Weak column)
Columns are considered to be weaker than beams when (Equation 7.3) is not fulfilled and exemption conditions are not met.
The following steps are applied for weak columns:
The validity of Equation (7.4) is checked. Provided that Equation (7.4) is fulfilled , it may be allowed that Equation (7.3) is not provided at some nodes above and / or below the relevant floor .
α i = V is / V ik ≥ 0.70 (7.4)
0.70 ≤ α i ≤ 1.0 interval, Eq. The bending moments and shear forces acting on the columns where (7.3) is provided at both the lower and upper joints are multiplied by the ratio (1 / αi).
If Equation (7.4) is not met for any floor , the structure should be considered as a frame with limited ductility level in cases where the ductility level can be accepted as frame , or mixed systems of ductility level can be used in combination with walls with high ductility level or strong column by increasing the system rigidity. conditions must be met.