In frames and beams with seismic requirements, stirrups in the overlapping range of longitudinal steel bars in tension should be encrypted.
In frame columns, the top surface of foundation shall be densified within the range of 1/3 above the column net height, and the bottom embedded parts, the bottom upper and lower columns shall be densified with stirrups within the range of 1 /6 and not less than 500mm, except the bottom lower part.
Frame column stirrups should be encrypted when passing through each beam slab.
The stirrup encryption area in the beam is located at the maximum shear, calculated from Lippi's 50mm position at the beam end support to the middle of the beam.
In the frame beam, the range of stirrup encryption area is determined according to the seismic strength grades Ⅰ, Ⅱ to Ⅳ, which is divided into two values: 2 times the beam height and 1.5 times the beam height, and the minimum value shall not be less than 500mm.
On the main beam at the intersection of primary and secondary beams, additional stirrups are also required to be encrypted. The calculation of the single-sided densified area starts from 50mm away from the edge of the secondary beam, and the width of the secondary beam plus the height difference of the bottom skin of the primary and secondary beams. Its encryption value is 8d of stirrup diameter, and it is not more than100 mm. ..