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Concrete Rectangular Beam Calculator to ACI 318-19 (IMP)'s banner
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Concrete Rectangular Beam Calculator to ACI 318-19 (IMP)

Welcome to the ACI 318-19 compliant RC Rectangular Beam Calculator. Streamline your design process with precise calculations for moment capacities, shear, and flexural requirements following the latest ACI standards.
📝This calculator follows ACI 318-19 guidelines using Imperial units.

Calculation

Materials

Concrete


f'c
:{"mathjs":"Unit","value":4000.0000000000005,"unit":"psi","fixPrefix":false}



Ec
:3604996.5325919534

Reinforcement


fy
:{"mathjs":"Unit","value":60000.00000000001,"unit":"psi","fixPrefix":false}



Es
:29000000psi



n
:8


Where:
  1. 
    
    is the specified compressive strength of concrete in psi
  1. 
    
    is the specified strength for non-prestressed reinforcement in psi
  1. 
    
    
    
    f'c
    :{"mathjs":"Unit","value":4000.0000000000005,"unit":"psi","fixPrefix":false}
    (19.2.2.1.b) is the Modulus of Elasticity for the concrete
  1. 
    
    is the Modulus of Elasticity for the reinforcement in psi.
  1. n is the modular factor, expressed as
    
    
    
    n
    :8.0

Cross Section

Geometry




Cross section



b
:{"mathjs":"Unit","value":14,"unit":"in","fixPrefix":false}



cover
:{"mathjs":"Unit","value":1.4999999999999998,"unit":"in","fixPrefix":false}



h
:{"mathjs":"Unit","value":23.999999999999996,"unit":"in","fixPrefix":false}



C1
:{"mathjs":"Unit","value":11.999999999999998,"unit":"in","fixPrefix":false}



L
:{"mathjs":"Unit","value":30,"unit":"ft","fixPrefix":false}



C2
:{"mathjs":"Unit","value":11.999999999999998,"unit":"in","fixPrefix":false}



Profile view


Reinforcement

Top


Ntop
:2



Top rebar
:#3

Bottom


Nbot
:4



Bot rebar
:#7

Stirrup


Legs
:2



S1
:{"mathjs":"Unit","value":8,"unit":"in","fixPrefix":false}



Stirrup rebar
:#3



S2
:{"mathjs":"Unit","value":16,"unit":"in","fixPrefix":false}

Where:
Ntop: number of bars used as top reinforcement.
Top rebar: diameter of the top reinforcement expressed as eighths of an inch.
Nbot: number of bars used as bottom reinforcement.
Bot rebar: diameter of the bottom reinforcement expressed as eighths of an inch.
Legs: number of vertical bars used as transverse reinforcement, assuming two legs for a regular stirrup.
Stirrup rebar: diameter of the transverse reinforcement expressed as eighths of an inch.
S1/S2: Longitudinal spacing of the transverse reinforcement in the corner and the centre of the beam, respectively. Measured center to center.

Loads

Loads Entry

Following the above axis system, you can introduce the different beam solicitations for each load.
3D Axis

Where:
D: Dead Load.
E: Earthquake Load.
F: Fluids Load.
H: Earth Load.

L: Live Load.
Lr: Roof Live Load.
S: Snow Load.
R: Rain Load.
W: Wind Load.


Use A(+) for compression.

Ultimate Loads

Max/Min Loads

Resume of the max/min applied ultimate loads to the structure according to the combinations established in the ACI318-19 and ASCE7-22.

1.2D+1.6L+0.5Lr
0.78 kips
10.70 kips-ft
1.2D+1.6L+0.5Lr
0.78 kips
10.70 kips-ft
0.9D+ 1.0W
0.14 kips
1.01 kips-ft
0.9D+ 1.0W
0.14 kips
1.01 kips-ft

Combinations of loads

The full table of applied ultimate loads to the structure according to the combinations established in the ACI318-19 and ASCE7-22.

0.00 kips
0.21 kips
1.57 kips-ft
0.00 kips
0.78 kips
10.70 kips-ft
0.00 kips
0.78 kips
10.70 kips-ft
0.00 kips
0.78 kips
10.70 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.18 kips
1.34 kips-ft
0.00 kips
0.18 kips
1.34 kips-ft
0.00 kips
0.18 kips
1.34 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.55 kips
7.19 kips-ft
0.00 kips
0.14 kips
1.01 kips-ft
0.00 kips
0.14 kips
1.01 kips-ft


Service Loads

The full table of applied service loads to the structure according to the combinations established in ASCE7-22.

1.00 kips
1.00 kips
1.00 kips
1.00 kips-ft
1.00 kips-ft
1.00 kips-ft
1.00 kips
2.00 kips
2.00 kips
2.00 kips-ft
2.00 kips-ft
2.00 kips-ft
1.00 kips
3.00 kips
3.00 kips
3.00 kips-ft
3.00 kips-ft
3.00 kips-ft
1.00 kips
1.70 kips
1.70 kips
1.70 kips-ft
1.70 kips-ft
1.70 kips-ft
1.00 kips
2.00 kips
2.00 kips
2.00 kips-ft
2.00 kips-ft
2.00 kips-ft
1.00 kips
2.50 kips
2.50 kips
2.50 kips-ft
2.50 kips-ft
2.50 kips-ft
1.00 kips
2.28 kips
2.28 kips
2.28 kips-ft
2.28 kips-ft
2.28 kips-ft
1.00 kips
2.50 kips
2.50 kips
2.50 kips-ft
2.50 kips-ft
2.50 kips-ft
1.00 kips
1.60 kips
1.60 kips
1.60 kips-ft
1.60 kips-ft
1.60 kips-ft
1.00 kips
3.10 kips
3.10 kips
3.10 kips-ft
3.10 kips-ft
3.10 kips-ft
1.00 kips
2.88 kips
2.88 kips
2.88 kips-ft
2.88 kips-ft
2.88 kips-ft
1.00 kips
3.10 kips
3.10 kips
3.10 kips-ft
3.10 kips-ft
3.10 kips-ft
1.00 kips
1.20 kips
1.20 kips
1.20 kips-ft
1.20 kips-ft
1.20 kips-ft

Elastic Deflections

In the following table, you can add the deflections due to each kind of load in case of a required deflection analysis. These deflections must be the product of an elastic analysis of the beam for the correct use of this page.


Flexural Strength

The flexural strength of the beam is calculated according to the standard literature for prismatic and simple reinforced beams. The

factor of 0.90 corresponds to the established in the ACI318-19; it can be changed according to the necessity of the user.

Mn =ρbd2fy(10.59ρfyfc)M_n\ =\rho bd^2f_y(1-0.59\rho \frac{f_y}{f'_c})


φf
:0.9



Mn, Bot
:242.53681730479084



φMn, Bot
:218.2831355743119



Mn,Top
:24.0750032188715



φMn,Top
:21.66750289698435


Shear strength

The

factor of 0.75 corresponds to the established in the ACI318-19; it can be changed according to the necessity of the user.
22.5.1.1
Nominal one-way shear strength at a section

Vn =Vc + VsV_n\ = V_c\ +\ V_s


φs
:0.75


(22.5.1.1)


Vn1
:49.852389621235396



Vn2
:49.852389621235396



φVn,1
:37.38929221592655



φVn,2
:37.38929221592655


Notice that two Shear Strengths are calculated in each section, each corresponding to the different spacings used in the beam.

Concrete Ultimate Design Shear



Vc1
:13.922724616984



Vc2
:13.922724616984

Vc shall not be taken greater than:

Vc, max= 5λfcbwdV_{c,\ max}=\ 5\lambda\sqrt{f'_c}b_wd
(22.5.5.1.1)


Vc,max+
:96.0146554568624



Vc,max-
:97.1214526379213

For nonprestressed members, Vc shall be calculated by Table 22.5.5.1:
A complete revision for each load combination was made for the following calculation. The final value is taken as the minimum calculated value in the table below. Finally, the

condition can be checked in the code revision.
Table 22.5.5.1 - ACI 318-19



Vc_22.5.5.1-1
:13.922724616984



Vc_22.5.5.1-2
:13.922724616984


1.4D
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+1.6L+0.5Lr
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+1.6L+0.5S
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+1.6L+0.5R
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6Lr+1.0L
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6S+1.0L
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6R+1.0L
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6Lr+0.5W
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6S+0.5W
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.6R+0.5W
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.0W+ 1.0L+0.5Lr
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.0W+ 1.0L+0.5S
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.0W+ 1.0L+0.5R
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
1.2D+ 1.0E+ 1.0L + 0.2S
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
0.9D+ 1.0W
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips
0.9D+ 1.0E
0.00 kips
38.41 kips
38.85 kips
30.62 kips
13.92 kips
24.33 kips
11.02 kips

Transverse Reinforcement Ultimate Design Shear


Vs=AvfydsV_s=\frac{A_vf_yd}{s}
(22.5.8.5.3)


Vs1
:35.9296650042514



Vs2
:35.9296650042514



Effective Deflection

Deflection Limits

The following deflections and deflection limits were calculated according to table 24.2.2 of ACI318-19. The deflection limit can be changed in the table below according to the actual case for the current calculation.
Table 24.2.2 - ACI 318-19


1.50 in
1.00 in
Check
4.10 in
0.75 in
Check
Where "Check" means the beam isn't accomplishing the code requirements.

Cracking Moment


Mcr=frIgytM_{cr}=\frac{f_rI_g}{y_t}
(24.2.3.5)


Mcr
:53.12626469082875



Cracked Moment of Inertia

The following calculation was made assuming a simple reinforced prismatic concrete beam.
Cracked Cross Section


Icr=b(kd)312+b(kd)22+nAs2(dkd)I_{cr}=\frac{b{(kd)}^3}{12}+\frac{b{(kd)}^2}{2}+n{A_s}^2(d-kd)


Icr, Bot
:1319.6867570644195



Icr, Top
:55.78928963530608


Effective Moment of Inertia

Table 24.2.3.5 - ACI 318-19

Where:


is the moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement in

.


is the moment of inertia of cracked section transformed to concrete (see chapter above) in

E=mc^2
.


is the cracking moment.


is the maximum moment in the member due to service loads at stage deflection is calculated.
A complete calculus for each combination of loads was made for the effective moment of inertia. (See the final chapter).

Time-dependent deflections

24.2.4.1.1
Additional time-dependent deflection resulting from creep and shrinkage of flexural members shall be calculated as the product of the immediate deflection caused by sustained load and the factor λΔ.
Table 24.2.4.1.3 - ACI 318-19

We use a time-dependent factor ξ of 2.0, corresponding to a sustained load duration of 60 or more months only for the dead loads, which are the one that remains sustained in time. A manual inclusion of this factor should be applied to the calculated deflection in case of a different condition.


ξBot
:2



ξTop
:2


λΔ=ξ1+50ρ\lambda_\Delta=\frac{\xi}{1+50\rho'}
(24.2.4.1.1)


λΔ,Bot
:1.930573759831715



λΔ,Top
:1.4325681149257323

Where:


is the reinforcement ratio for the compressive reinforcement. We use the top ratio for positive flexural moments and the bottom ratio for negative flexural moments.

Service load calculated deflections

For immediate deflections, the dead load deflection is calculated first and then subtracted from the total combination deflection. The inmmediate deflection calculation is made only for live loads included combinations.

0.00 kips
0.53 kips
5.51 kips-ft
1.00 in
16128.00 in4
1
1.00 in
2.00 in
0.00 kips
0.53 kips
6.97 kips-ft
2.00 in
16128.00 in4
1
2.00 in
1.00 in
3.00 in
0.00 kips
0.15 kips
1.12 kips-ft
2.00 in
16128.00 in4
1
2.00 in
1.00 in
3.00 in
0.00 kips
0.15 kips
1.12 kips-ft
1.70 in
16128.00 in4
1
1.70 in
2.70 in
0.00 kips
0.15 kips
1.12 kips-ft
2.00 in
16128.00 in4
1
2.00 in
3.00 in
0.00 kips
0.43 kips
5.51 kips-ft
2.50 in
16128.00 in4
1
2.50 in
1.50 in
3.50 in
0.00 kips
0.43 kips
5.51 kips-ft
2.28 in
16128.00 in4
1
2.28 in
3.28 in
0.00 kips
0.43 kips
5.51 kips-ft
2.50 in
16128.00 in4
1
2.50 in
3.50 in
0.00 kips
0.15 kips
1.12 kips-ft
1.60 in
16128.00 in4
1
1.60 in
2.60 in
0.00 kips
0.43 kips
5.51 kips-ft
3.10 in
16128.00 in4
1
3.10 in
4.10 in
0.00 kips
0.43 kips
5.51 kips-ft
2.88 in
16128.00 in4
1
2.88 in
3.88 in
0.00 kips
0.43 kips
5.51 kips-ft
3.10 in
16128.00 in4
1
3.10 in
4.10 in
0.00 kips
0.09 kips
0.67 kips-ft
1.20 in
16128.00 in4
1
1.20 in
2.20 in


Code Check

In the following tables, the "Check" condition corresponds to a failure of accomplishment in the checked state.

Strength

Max/Min


1.2D+1.6L+0.5Lr
0.78 kips
10.70 kips-ft
0.49
N/A
0.02
0.02
0.04
OK
1.2D+1.6L+0.5Lr
0.78 kips
10.70 kips-ft
0.49
N/A
0.02
0.02
0.04
OK
0.9D+ 1.0W
0.14 kips
1.01 kips-ft
0.05
N/A
0
0
0.01
OK
0.9D+ 1.0W
0.14 kips
1.01 kips-ft
0.05
N/A
0
0
0.01
OK

Ultimate Combinations


0.00 kips
0.21 kips
1.57 kips-ft
0.07
N/A
0
0
0.01
OK
0.00 kips
0.78 kips
10.70 kips-ft
0.49
N/A
0.02
0.02
0.04
OK
0.00 kips
0.78 kips
10.70 kips-ft
0.49
N/A
0.02
0.02
0.04
OK
0.00 kips
0.78 kips
10.70 kips-ft
0.49
N/A
0.02
0.02
0.04
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.18 kips
1.34 kips-ft
0.06
N/A
0
0
0.01
OK
0.00 kips
0.18 kips
1.34 kips-ft
0.06
N/A
0
0
0.01
OK
0.00 kips
0.18 kips
1.34 kips-ft
0.06
N/A
0
0
0.01
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.55 kips
7.19 kips-ft
0.33
N/A
0.01
0.01
0.03
OK
0.00 kips
0.14 kips
1.01 kips-ft
0.05
N/A
0
0
0.01
OK
0.00 kips
0.14 kips
1.01 kips-ft
0.05
N/A
0
0
0.01
OK


Geometry

Select the correct support condition for the current analysed beam:


Support
:Simply supported


22.50 in
Ok
Table 9.3.1.1 - ACI 318-19

Select the correct exposure condition for the concrete:


Condition
:Cast against and permanently in contact with ground


3.00 in
Check
Table 20.5.1.3.1 - ACI 318-19


Reinforcement

Longitudinal Reinforcement

According to 9.6.1.2 As shall be the larger of:

As,min=3fcfybwdA_{s,min}=\frac{3\sqrt{f'_c}}{f_y}b_wd

As,min=200fybwdA_{s,min}=\frac{200}{f_y}b_wd

1.02 in²
Check
Ok


Transversal Reinforcement

According to 9.6.3.4 If shear reinforcement is required... Av shall be the greater of:

Av,min=0.75fcfybwA_{v,min}=\frac{0.75\sqrt{f'_c}}{f_y}b_w

As,min=50fybwA_{s,min}=\frac{50}{f_y}b_w


0.012 in²/in
Ok


Properties

Geometry



Ag
:336

Gross area of concrete section


Ig
:16128

Moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement.


yt
:12

Distance from centroidal axis of gross-section, neglecting reinforcement, to tensional face.

Reinforcement

Top Rebar


Øtop rebar
:0.375



As, top_rebar
:0.110446616727766



AsT, top_rebar
:0.220893233455532



ρTop
:0.0007192290873603009



dtop
:21.9375

Bottom Rebar


Øbot rebar
:0.875



As, bot_rebar
:0.60132046885117



AsT, bot_rebar
:2.40528187540468



ρBot
:0.00792188349248143



dbot
:21.6875

Transverse Rebar


Øst rebar
:0.375



As, st_rebar
:0.110446616727766



AsT, st_rebar
:0.220893233455532