Resources Numerical accuracy
Calculations
Every calculation under our calculation policies: what it works out, its formula and the precision it runs at. Open one to see its code as it is in the released app.
Calculations
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Model to paper
The scale and offset that place a view on the sheet.
paper = origin + model ÷ s
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Part of a member inside a view's slab
The stretch of a member's axis that lies inside the band a plan or elevation shows.
a = (lo − s0) ÷ k, b = (hi − s0) ÷ k; k = x̂·A
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Corners of a part's box
The eight corners of a part's section box, moved onto the cut faces at mitre ends.
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Outline of a projected part
The convex outline of a part's projected box corners.
pop while cross(o, a, b) ≤ 1e-9
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Where two paper lines cross
The position along one segment where it crosses another.
t = ((c − a) × q) ÷ (r × q), u = ((c − a) × r) ÷ (r × q)
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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A hole's center and axis
Where a hole is in the model and which way it goes through the part.
flange hole: v = ±(depth ÷ 2 − t ÷ 2)
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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An assembly in its main part's coordinates
The welded-on parts, holes and overall extents of an assembly, measured along and across its main part.
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Weights in an assembly's part list
The weight of each part, of each line and of the whole assembly in the part list.
total = Σ n × weight
Dimensions and views on drawing sheets drawings.js64-bit- DetailCraft
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Rounding to six decimals
The rounding applied to every number written to the file.
round(v × 10⁶) ÷ 10⁶
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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Text position and height
Where a line of text sits and how tall it is in the DWG model.
height = size × 0.718
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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Line and polyline vertices
The points of each line, polyline and solid fill in the DWG model.
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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Outline of a filled circle
The polygon used as the boundary of a filled circle.
(c_x + r·cos(2π·i ÷ 48), c_y + r·sin(2π·i ÷ 48))
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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A number in the DXF text
How each coordinate is printed in the DXF file.
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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Line weight of a pen
The line weight written for a layer, in hundredths of a millimeter.
round(w × 100)
Drawing sheets as DWG and DXF dwgout.js64-bit- DetailCraft
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Model point to screen
Where a model point is drawn on the canvas.
Erection movie player erection-html.js32-bit, display only- DetailCraft
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Where a pick is at a given minute
The offset of a lifted piece from its final place while the movie plays.
Erection movie player erection-html.js32-bit, display only- DetailCraft
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Load chart cleaned
The chart rows kept: sorted by radius, with a capacity that never rises as the radius grows.
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Capacity at a radius
The chart capacity that applies at a given radius.
capacity = kg of the first row with radius ≥ r; 0 beyond the last row
Erection plan: picks, crane loads and times erection.jsExact- DetailCraft
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Weight and center of gravity of a pick
The weight of an assembly and the point its weight acts at.
W = Σ w_i; cg = Σ w_i·(a_i + b_i) ÷ 2 ÷ W
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Storey a pick belongs to
Which storey a pick is erected with, for the order of the sequence.
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Load, radius and share of the chart
The load on the hook, the working radius, the chart capacity there and the share of it used.
load = W·(1 + rigging% ÷ 100) + deduction; radius = max(r_pick, r_set); share = load ÷ capacity
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Time of a pick
How long a pick takes and when it starts and ends.
travel = (plan distance + top height) ÷ 1000; minutes = hook + travel ÷ speed + set + release; start = max(crane free, supports done)
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Status of a pick
Whether a pick is fine, over the chart, above the chosen limit, out of reach or too high for the hook.
over when share > 1; high when share > limit
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Plan totals
The total weight, the total time, the heaviest pick and the pick that uses most of the chart.
total kg = Σ W; minutes = max end time
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Figures in the plan's warnings
The numbers quoted when a pick is over the chart, over the limit or too high.
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Data handed to the movie
The picks, boxes and times saved into the erection movie page.
Erection plan: picks, crane loads and times erection.js64-bit- DetailCraft
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Concrete strength from the footing's text
The concrete strength in MPa read from text such as 4000 psi, 28 MPa or C30/37.
MPa = psi × 0.00689476
Footing design checks foundation.js64-bit- DetailCraft
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Support reaction as a footing load
Turns an analysis support reaction into the load on the footing in the footing's own axes.
P = F_z ÷ 1000; (V_x, V_y) = rot(−F) ÷ 1000; (M_x, M_y) = rot(−M) ÷ 10⁶
Footing design checks foundation.js64-bit- DetailCraft
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Effective depths
The depth from the top of the footing to the middle of each layer of bottom bars.
d_X = H − c − d_bX ÷ 2; d_Y = H − c − d_bX − d_bY ÷ 2
Footing design checks foundation.js64-bit- DetailCraft
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Service load and its eccentricity
The total vertical load on the soil and where it acts.
W = γ_c·A·h + γ_s·A·fill; N = ΣP + W; e_x = (ΣP·x + ΣM_y + h·ΣV_x) ÷ N
Footing design checks foundation.js64-bit- DetailCraft
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Pressure under a rigid rectangle
The plane of soil pressure under the footing, with part of the base lifting off when the load is outside the kern.
q = a + b·x + c·y; inside the kern: a = N ÷ A, b = 12·N·e_x ÷ (A·L²), c = 12·N·e_y ÷ (A·B²)
Footing design checks foundation.js64-bit- DetailCraft
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Three equations in three unknowns
Solves the Newton step for the pressure plane.
Footing design checks foundation.js64-bit- DetailCraft
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Soil force and moment beyond a cut
The upward soil force on the part of the base beyond a cut, and its moment about the cut.
V = Σ q·dw·ds; M = Σ q·dw·ds·(t − cut)
Footing design checks foundation.js64-bit- DetailCraft
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Demand over capacity
The ratio each check reports and whether it passes.
ratio = demand ÷ capacity; ok when ratio ≤ 1 + 1e-9
Footing design checks foundation.js64-bit- DetailCraft
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Sliding and overturning
The safety factors against sliding on the base and against overturning.
H = √(V_x² + V_y²); sliding: fs·H ≤ μ·N; overturning: FS = 1 ÷ max(|e_x| ÷ (L ÷ 2), |e_y| ÷ (B ÷ 2))
Footing design checks foundation.js64-bit- DetailCraft
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Shear and moment on a cut, and the largest moment
The shear and moment on a cut across the footing, and the cut with the largest moment.
V = V_soil − ΣP; M = M_soil − Σ(P·arm + M_col + h·V_col)
Footing design checks foundation.js64-bit- DetailCraft
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Bending steel
The steel provided per meter, the steel bending needs and the minimum steel.
M_u per m = |M| ÷ (b ÷ 1000) × 10⁶; A_s provided = A_bar × 1000 ÷ s; A_s,min = ρ_min × 1000 × H
Footing design checks foundation.js64-bit- DetailCraft
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One-way shear
The largest shear at a distance d from each column face against the concrete's shear strength.
V_u = max |V| at face ± d; capacity = 0.75 × V_c
Footing design checks foundation.js64-bit- DetailCraft
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Bar development length
The straight length a bar needs beyond the column face to develop its strength.
l_d = max(300, f_y ÷ (k·λ·√f′c) × d_b); k = 2.1, 1.7, 1.4 or 1.1
Footing design checks foundation.js64-bit- DetailCraft
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Hooked bar development length
The length a hooked bar needs.
l_dh = max(8·d_b, 150, 0.24·f_y ÷ (λ·√f′c) × d_b)
Footing design checks foundation.js64-bit- DetailCraft
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Length available for development
The length of bar from the farthest column face to the end of the footing, less the cover.
available = side ÷ 2 − (|x_col| + c_col ÷ 2) − cover
Footing design checks foundation.js64-bit- DetailCraft
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Critical section for punching
The perimeter at d ÷ 2 from a column, cut off at the footing's edge, with its length, centroid and section properties.
b_o = Σ l; J = Σ (d·l³ ÷ 12 + l·d³ ÷ 12 along the bending direction) + d·l·arm²
Footing design checks foundation.js64-bit- DetailCraft
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Punching shear
The shear stress on the critical section against the concrete's punching strength.
v_u = V_u ÷ (b_o·d) + γ_v·M·c ÷ J (both directions); v_c = min(0.33, 0.17·(1 + 2 ÷ β), 0.083·(2 + α_s·d ÷ b_o))·λ_s·λ·√f′c
Footing design checks foundation.js64-bit- DetailCraft
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Share of the base in contact
The share of the base still pressing on the soil when part has lifted off.
share = cells with q > 0 ÷ 1600
Footing design checks foundation.js64-bit- DetailCraft
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Settlement at the corner of a loaded rectangle
The settlement under the corner of a flexible rectangle carrying a uniform pressure on an elastic half-space.
w = q·b·(1 − ν²) ÷ (π·E) × (m·ln((1 + √(m² + 1)) ÷ m) + ln(m + √(m² + 1))); m = long side ÷ short side
Settlement, flexible mats, pile groups and retaining walls foundation.js64-bit- DetailCraft
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Settlement at the center and corner of a footing
The elastic settlement at the middle and at a corner of the footing.
center = 4 × corner of the quarter rectangle
Settlement, flexible mats, pile groups and retaining walls foundation.js64-bit- DetailCraft
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Mat mesh size and concrete stiffness
The element size of the plate mesh and the concrete's modulus.
size = max(min(clamp(min(L, B) ÷ 14, 150, 600), max(100, smallest column ÷ 3)), √(L·B ÷ 8000)); E_c = 4700·√f′c
Settlement, flexible mats, pile groups and retaining walls foundation.js64-bit- DetailCraft
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Soil springs under the nodes
The spring stiffness under each node from the subgrade modulus and the area the node carries.
A = |d₁ × d₂| ÷ 2 (the two diagonals); k_node = k_s × 10⁻⁶ × Σ A ÷ 4
Settlement, flexible mats, pile groups and retaining walls foundation.js64-bit- DetailCraft
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A column load spread over its footprint
The force on each node inside a column's footprint.
R_i = P ÷ n + M_y·dx_i ÷ Σdx² − M_x·dy_i ÷ Σdy²
Settlement, flexible mats, pile groups and retaining walls foundation.js64-bit- DetailCraft
A calculation is added only after its source was read. Each statement can be checked in the code shown on its policy's page; the app repositories are public. When a release changes a calculation, its page says so until it has been read again.