According to the standard 03G 10 1- 1, the length of the first row of steel bars at the beam support is Ln/3, the length of the second row of steel bars is LN/4, and the length of the third row of steel bars is not specified, so it is best to calculate it by design specification or Ln/4.

Beam support refers to the contact part between beam and column or other beams. Because of the rigidity of beams and columns, the bearing can generally be imagined as an immovable rigid domain, and the rigid domain can be imagined as a bearing. The calculation method of the rigid domain is that the rigid domain of the column is equal to half of the column width minus a quarter of the beam height, and the rigid domain of the beam is equal to the beam support, which is the support at both ends or in the middle of the beam and plays the role of supporting the beam.