Development of Reinforcement per ACI 31819 with ideCAD
How does ideCAD calculate development length according to ACI 31819?
The √FC values used to calculate development length should not exceed 100 psi. This is automatically controlled according to 25.4.1.4.
For deformed bars or deformed wires, l_{d} is calculated automatically by Table 25.4.2.3.
Symbols
ψ_{e} = factor used to modify development length based on reinforcement coating
ψ_{g} = factor used to modify development length based on the grade of reinforcement
ψ_{s} = factor used to modify development length based on reinforcement size
ψ_{t} = factor used to modify development length for casting location in tension
λ = modification factor to reflect the reduced mechanical properties of lightweight concrete relative to normalweight concrete of the same compressive strength
K_{tr} = transverse reinforcement index, in.
A_{tr} = total crosssectional area of all transverse reinforcement within spacing s that crosses the potential plane of splitting through the reinforcement being developed, in.^{2}
d_{b} = nominal diameter of bar, wire, or prestressing strand, in
f'_{c} = specified comprehensive strength of concrete, psi
f_{y} = specified yield strength of nonprestressed reinforcement, psi
l_{d} = development length in tension of deformed bar, deformed wire, plain and deformed welded wire reinforcement, or pretensioned strand.
s = centertocenter spacing of items, such as longitudinal reinforcement, transverse reinforcement, tendons, or anchors.
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Development of reinforcement
The fact embedment length should adopt determined tension or compression in reinforcement at each member section; hook, head deformed bar, mechanical device, or a combination according to 25.4.1.
Heads and hooks should not be used to develop bars in compression, according to 25.4.1.2.
The √fc values used to calculate development length should not exceed 100 psi. It’s automatically controlled according to 25.4.1.4.
Development of deformed bars and deformed wires in tension
Development length l_{d}_{ }for deformed bars and deformed wires in tension is controlled the greater of below:
Length calculated in accordance with 25.4.2.3 or 25.4.2.4 using the applicable modification factors of 25.4.2.5
12 in
For deformed bars or deformed wires, l_{d} is calculated in accordance with Table 25.4.2.3.
Spacing and cover  #6 and smaller bars  #7 and larger bars 

Clear spacing of bars or wires 


Other Cases 


All modification factors for developing deformed bars and wires are chosen automatically according to Table 25.4.2.5.
Modification factor  Condition  Value of factor 

 Lightweight concrete  0.75 
Normalweight concrete  1.0  
Reinforcement grade, ψ_{g}  Grade 40 or Grade 60  1.0 
Grade 80  1.15  
Grade 100  1.3  
Epoxy ψ_{e}  Epoxycoated or zinc and epoxy dualcoated reinforcement with clear cover less than 3db or clear spacing less than 6d_{b}  1.5 
Epoxycoated or zinc and epoxy dualcoated reinforcement for all other conditions  1.2  
Uncoated or zinccoated (galvanized) reinforcement  1.0  
 No. 7 and larger bars  1.0 
No. 6 and smaller bars and deformed wires  0.8  
 More than 12 in. of fresh concrete placed below horizontal reinforcement  1.3 
Other  1.0 
Alternatively, l_{d} can be calculated with Eq. 25.4.2.4a and 25.4.2.4b.
(c_{b} + K_{tr})/d_{b} is not exceeded 2.5,
Where n is the number of bars, wires being developed, or lap spliced along the splitting plane, it is permitted to use K_{tr} = 0 reinforcement is present or required.
When Eq. 25.4.2.4a is calculated with the prerequisite (c_{b} + K_{tr})/d_{b} = 2.5 is used with the development length can be determined as less than calculated according to Table 25.4.2.3.
Development of standard hooks in tension
Development length l_{dh} for deformed bars in tension terminating in a standard hook is the greater of
8db
6 in.
25.4.3.3 The total crosssectional area of ties or stirrups confining hooked bars A_{th} shall consist of (a) or (b):
(a) Ties or stirrups that enclose the hook and satisfy 25.3.2.
(b) Other reinforcement enclosing the hook, that extends at least 0.75dh from the enclosed hook in the direction of the bar in tension, and is in accordance with (1) or (2).
For members with confining reinforcement that is both parallel and perpendicular to l_{dh}, it shall be permitted to use the value of A_{th} based on (1) or (2) that results in the lower value of l_{dh}.
(1) Two or more ties or stirrups shall be provided parallel to l_{dh} enclosing the hooks, evenly distributed with a centertocenter spacing not exceeding 8d_{b}, and within 15d_{b} of the centerline of the straight portion of the hooked bars, where db is the nominal diameter of the hooked bar.
(2) Two or more ties or stirrups shall be provided perpendicular to l_{dh}, enclosing the hooked bars, and evenly distributed along l_{dh} with a centertocenter spacing not exceeding 8d_{b}, where d_{b} is the nominal diameter of the hooked bar.
According to 25.4.3.4, for bars being developed by a standard hook at discontinuous ends of members with both side cover and top (or bottom) less than 21/2 in., the rules below should be supplied:
The hook is enclosed along l_{dh} within ties or stirrups perpendicular to l_{dh} at s≤3d_{b}
The first tie or stirrup encloses the bent portion of the hook within 2d_{b} of the outside of the bend
where d_{b} is the nominal diameter of the hooked bar.
25.4.9  Development of deformed bars and deformed wires in compression
Development length l_{dc} for deformed bars and deformed wires in compression is greater of
 Length calculated in accordance with 25.4.9.2
 8 in.
According to 25.4.9.2, l_{dc} is the greater of (a) and (b), using the modification factors in Table 25.4.9.3
ψ_{r} is permitted to be taken as 1.0.
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