How is concrete shear capacity Vc calculated per ACI 318-19?

Per ACI 318-19 Section 22.5, Vc = 0.17λ√f'c × bw × d (simplified), where λ is the lightweight factor, f'c is in MPa, bw is web width, and d is effective depth.

What is the minimum shear reinforcement required per ACI 318-19?

Per ACI 318-19 Section 9.6.3, Av,min/s = 0.062√f'c × bw/fyt ≥ 0.35bw/fyt when Vu > 0.5φVc.

When can stirrups be omitted in a concrete beam?

Stirrups may be omitted when Vu ≤ 0.5φVc per ACI 318-19 Section 9.6.3.1, typically in lightly loaded members with small cross-sections.

What is the maximum stirrup spacing per ACI 318-19?

Per ACI 318-19 Section 9.7.6.2.2, maximum stirrup spacing is the lesser of d/2 or 600 mm when Vs ≤ 0.33√f'c bwd, and d/4 or 300 mm when Vs exceeds that limit.

How is the shear DCR calculated?

Shear DCR = Vu / φVn, where φVn = φ(Vc + Vs). A DCR ≤ 1.0 means shear design is adequate.

Concrete Design

Beam Shear

ACI 318-19

Knowledge Projects

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Beam Shear Design

ACI 318-19 §22.5 — Stirrup design for shear

Loads

V_u?

N_u?

Geometry

Width (b)

Height (h)

Cover

dauto?

Material

f'c

λ (lightweight)?

A_s,longauto?

ρ_w is assumed 1%. Enable A_s,long above for a more accurate Vc.

Stirrups

Stirrup Size

Spacing (s)

Av (2 legs)auto?

s,reqauto?

✓ OK

Layout:

Elevation

Cross Section

SFD

Stirrup Detail

Step	Formula	Substitution	Result
Vc	0.66λ(ρw)^(1/3)√(f'c)·b·d	0.66×1×(1%)^(1/3)×√30×300×438	102.2 kN

Step	Formula	Substitution	Result
Vs	Av·fy·d/s	157×400×438/150	183.2 kN

Step	Formula	Substitution	Result
φVn	φ(Vc+Vs)	0.75×(102.2+183.2)	214 kN	✓

Step	Formula	Substitution	Result
DCR	Vu/φVn	180/214	0.84	✓

Step	Formula	Substitution	Result
s,req	s_req	199.4	199.4 mm
s,max	s_max	219	219 mm
s,prov	s	150	150 mm	✓

Results

Shear DCR

0.84 · PASS

Shear84%

φVn214 kN

Vu180 kN

Vc102.2 kN

Vs183.2 kN

s,req199.4 mm

s,design190 mm

s,max219 mm

s,prov150 mm

Av,min0.26 mm²

ρw1%

This calculation is for preliminary design verification only. All results must be independently verified by a licensed professional engineer before use in construction documents.

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Concrete Design

Beam Shear

ACI 318-19

Knowledge Projects

Dark ColorDark MonoLight ColorLight Mono

Beam Shear Design

ACI 318-19 §22.5 — Stirrup design for shear

Loads

V_u?

N_u?

Geometry

Width (b)

Height (h)

Cover

dauto?

Material

f'c

λ (lightweight)?

A_s,longauto?

ρ_w is assumed 1%. Enable A_s,long above for a more accurate Vc.

Stirrups

Stirrup Size

Spacing (s)

Av (2 legs)auto?

s,reqauto?

✓ OK

Layout:

Elevation

Cross Section

SFD

Stirrup Detail

Step	Formula	Substitution	Result
Vc	0.66λ(ρw)^(1/3)√(f'c)·b·d	0.66×1×(1%)^(1/3)×√30×300×438	102.2 kN

Step	Formula	Substitution	Result
Vs	Av·fy·d/s	157×400×438/150	183.2 kN

Step	Formula	Substitution	Result
φVn	φ(Vc+Vs)	0.75×(102.2+183.2)	214 kN	✓

Step	Formula	Substitution	Result
DCR	Vu/φVn	180/214	0.84	✓

Step	Formula	Substitution	Result
s,req	s_req	199.4	199.4 mm
s,max	s_max	219	219 mm
s,prov	s	150	150 mm	✓

Results

Shear DCR

0.84 · PASS

Shear84%

φVn214 kN

Vu180 kN

Vc102.2 kN

Vs183.2 kN

s,req199.4 mm

s,design190 mm

s,max219 mm

s,prov150 mm

Av,min0.26 mm²

ρw1%

This calculation is for preliminary design verification only. All results must be independently verified by a licensed professional engineer before use in construction documents.

Beam Shear

Beam Shear Design

Loads

Geometry

Material

Stirrups

Beam Shear Design

Given:

Material Properties:

Concrete Shear Capacity

Steel Shear Capacity

Design Capacity

DCR Check

Spacing Check

Beam Shear

Beam Shear Design

Loads

Geometry

Material

Stirrups

Beam Shear Design

Given:

Material Properties:

Concrete Shear Capacity

Steel Shear Capacity

Design Capacity

DCR Check

Spacing Check