RC Corbel Design (ACI318-05)

Project

Job Ref.

Section

Sheet no./rev.

SAFORY 00000

1 Calc. by

Date

D

d

Date

App'd by

Date

4/29/2011

Vu

Main tension bars 2 3

Chk'd by

Steel angle

a

Nuc    2    /    d    n    i    m

Sh Sh Sh

Horizontal bars

d h

Framing bars

RC SINGLE CORBEL DESIGN TO ACI 318-05 Corbel geometry ;Width of corbel; corbel;

b = 20.000 in

;Total thickness of corbel; corbel;

h = 35.000 in

;Depth to main reinforcement; reinforcement;

d = 28.000 in

Material properties ;Yield strength of reinforcement; reinforcement;

fy = 60000 psi

;Compressive strength of concrete; concrete;

f’c = 4000 psi

Type of concrete; concrete;

Normal weight

Unit weight of concrete; concrete;

 = 1.00

Corbel construction; construction;

Monolithic

Coefficient of friction; friction;

= 1.4

= 1.40

Design load data ;Factored vertical load ;

Vu = 2.000 kips

;Distance of vertical load from face of column; column;

a = 5.000 in

;Horizontal force acting on corbel; corbel;

Nuc = 2.000 kips

;Strength reduction factor; factor;

 = 0.750

Vertical load capacity check Nominal vertical load; load;

Vn = Vu / = 2.667 kips

Nominal vertical load capacity; capacity;

Vn_cap = min(0.2  f’c  b  d, 800 psi  b  d) = 448.000 kips PASS - Nominal vertical load is less than the nominal vertical load capacity 

Find shear friction reinforcement Minimum horizontal force acting on corbel; corbel;

Nuc_min = 0.2  Vu = 0.400 kips

Horizontal force acting on corbel; corbel;

Nuc_act = max(Nuc, Nuc_min) = 2.000 kips

For balanced condition; condition;

 j = 0.85

Area for shear friction reinforcement; reinforcement;

Avf = Vn / (fy ) = 0.032 in2 Af = [(Vu  a) + (Nuc_act  (h –d))] / (  fy  j  d) = 0.022 in2

Nominal area required; required;

An = Nuc_act / ( fy) = 0.044 in2

Project

Job Ref.

Section

Sheet no./rev.

SAFORY 00000

2 Calc. by

Date

D

Chk'd by

Date

App'd by

Date

4/29/2011

Main tension reinforcement check Minimum area of tension reinforcement;

Asc_min = 0.04  f’c  b  d / fy = 1.493 in2

Area of tension reinforcement required;

Asc = max([(2  Avf) / 3] + An, Af + An) = 0.067 in2 Asc_req = max(Asc, Asc_min) = 1.493 in2

Main tension reinforcement;

5 No.5 bars

Diameter of tension bars;

Dtension = 0.625 in

Number of tension bars;

Ntension = 5

Area of tension reinforcement provided;

Asc_prov = Ntension    Dtension2 / 4 = 1.534 in2 PASS - Tension reinforcement is adequate 

Horizontal reinforcement check Minimum area of horizontal reinforcement;

Ah_min = 0.5 * (A sc_req – An) = 0.724 in2

Area of horizontal reinforcement required;

Ah = max(Avf / 3, Af / 2) = 0.011 in2 Ah_req = max(Ah, Ah_min) = 0.724 in2

Horizontal reinforcement;

5 No.4 bars

Diameter of horizontal bars;

Dhorizontal = 0.500 in

Number of horizontal bars;

Nhorizontal = 5

Area of horizontal reinforcement provided;

Ah_prov = 2  Nhorizontal    Dhorizontal 2 / 4 = 1.963 in2 PASS - Horizontal reinforcement is adequate 

Maximum spacing of horizontal bars;

Sh_max = 2  d / (3  Nhorizontal ) = 3.733 in

Actual spacing of horizontal bars;

Sh = 2.000 in PASS - Horizontal bar spacing is adequate 

Design Summary Single corbel 20.0'' wide by 35.0'' deep with 4000 psi concrete and 60000 psi steel Provide main tension reinforcement as 5 No. 5 bars Provide horizontal reinforcement as 5 No. 4 link bars at maximum 2.000'' centres