7/29/2019 SHEAR DESIGN OF DEEP BEAMS.doc

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SHEAR DESIGN OF DEEP BEAMS

Basic Design Relationship: Vn > Vu

Design Procedure

1) Check Ln/d for distributed loads, critical section is 0.15 Ln from face of support

> for concentrated loads, critical section is 0.5a from location of concentrated force

3) Check Vn < 8(fc) bwd for Ln/d < 2

OR Vn < 2/3 (10+ Ln/d)(fc) bwd for 2 < Ln/d < 5

4) Compute Vc = 2(fc) bwd

Note: A more detailed expression is given in ACI 11.8.7

5) Vs = Vn - Vc

6) Design shear reinforcement

a) simply supported beams:

b) Continuous beams

Use minimum steel for horizontal shear reinforcement

7) Minimum requirements

Av > 0.0015 bw s

and s d/5 or 18

Avh > 0.0025 bw s2

and s2 d/3 or 18

NOTE: DESIGN AT CRITICAL SECTION APPLIES THROUGHOUT SPAN

dfs

A

s

AV y

dLn

vhdLn

v

s

+

+=

12

11

12

1

2

s

dfAV

yv

s =