Rebar Development and Lap

1 · Input data

The development length of a deformed bar and the length of a lap splice to ACI 318-25 Chapter 25 — Reinforcement Details, for a straight bar, a standard hook, a bar in compression and a lap splice, in tension and in compression. The card asks for the condition, never for a factor: every modification factor the code applies — λ, ψ_g, ψ_e, ψ_s, ψ_t, ψ_cc, ψ_r — is a table lookup keyed to a condition declared here, and the solution card prints the factor it took with the table and the printed page it came from. The parameters a branch does not use are dimmed, not silently ignored. Press Compute the lengths when the card is complete.

The bar and the concrete

Bar size

Reinforcement grade

Concrete compressive strength f′_c, psi

Concrete weight class — the factor λ

The action and the anchorage

Action in the bar

Anchorage

Route to the tension development length

Coating of the bar — the factor ψ_e

Casting position — the factor ψ_t

What (c_b + K_tr)/d_b needs — a straight bar or a lap splice in tension, §25.4.2.4

Clear cover to the bar being developed, in.

Clear spacing between the bars being developed, in.

Stirrups or ties throughout ℓ_d not less than the Code minimum — Table 25.4.2.3 row 1

How K_tr is taken

Area of transverse reinforcement crossing the plane of splitting, A_tr, in²

Spacing of the transverse reinforcement, s, in.

Number of bars being developed along the plane of splitting, n

A standard hook in tension, §25.4.3

Hook type

Side cover normal to the plane of the hook, in.

Cover on the bar extension beyond the hook, in.

Confining reinforcement along the hook — the factor ψ_r

The hook is at a discontinuous end of a member with both side cover and top (or bottom) cover to the hook less than 2-1/2 in. — §25.4.3.3, which forces ψ_r = 1.0

A bar in compression, §25.4.9

Confining reinforcement of the compression bar — the factor ψ_r

A lap splice, §25.5

Splice type

A_s,provided/A_s,required over the length of the splice

Maximum percent of A_s spliced within the required lap length

Mechanical splice class — Table 25.5.7.2

Reduced embedment, §25.4.10

Take reduced embedment in accordance with §25.4.10?

A_s,provided, in²

A_s,required, in²

Exclusions of §25.4.10.2 — any one of them forbids reduced embedment here

2 · Solution

No solution yet — complete the card above and press Compute the lengths. This card stays empty until a solution is computed, and it is emptied again the moment any input changes, so a displayed solution always belongs to the inputs on screen.