Horizontal Shear
All loads acting on the section are assumed to generate horizontal shear. The design is based on the following equation:
LFD Eq. 9-31a:
The required amount of horizontal shear steel that must cross the interface between the top of the beam and slab is computed for the following two conditions:
- A smooth finish (not intentionally roughened) on the top of the beam (Avh-sm).
- A rough finish on the top of the beam (Avh-rg).
If the surface is smooth and Vnh is less than 80 bvd, minimum ties of 50 bvs/fy are sufficient, as specified in LFD Art. 9.20.4.3(b).
If the surface is intentionally roughened and Vnh is less than 80 bvd, then no ties are required, as specified in LFD Art. 9.20.4.3(a).
LFD Art. 9.20.4.3(c) specifies that if the surface is intentionally roughened and Vnh is greater than 80 bvd, but less than 350 bvd, then minimum ties of 50 bvs/fy are sufficient, as specified in LFD Art. 9.20.4.5(a).
If the required shear capacity (Vnh) is greater than 80 bvd for smooth or 350 bvd for rough, then additional steel is provided to generate the additional capacity, as stated in LFD Art. 9.20.4.3(d).