B13 · Intermediate · 1–2 hours
BS 8110 — two-way slab (Tables 3.13–3.15)
Rectangular panel spanning two ways: restrained (Table 3.14) or simply supported (Table 3.13) moments, steel each way and over continuous edges, span/d, Table 3.15 support shears and corner torsion steel.
Tool: Education preview · Lesson: In preparation · Example: Built awaiting check · Workbook: Not applicable · Assessment: Not started
Outstanding before release: Engineering checker to verify clause mapping against BS 8110-1 and sign off v0.1.0. Cross-checked against TCC RCC94 Two-way Slabs (Tables) (see evidence).
Sources
| Role | Source | Note |
|---|---|---|
| Primary | BS 8110-1:1997 (+A1–A3): 3.5.3.3 & Table 3.13 (eqs 12–13); 3.5.3.4–3.5.3.5 & Table 3.14 (eqs 14–18, torsion steel 3.5.3.5); 3.5.3.7 & Table 3.15 (eqs 19–20); 3.4.4.4; Table 3.25; 3.4.6 / 3.5.7 (span/d on the short span); 3.5.5 (shear); 3.12.11.2.7 | Withdrawn standard — education and legacy checks only (mapping awaiting checker verification) |
| Supporting | Cross-check reference: The Concrete Centre RCC94 Two-way Slabs (Tables) (external tool; not used in the implementation) | Comparison evidence only (mapping awaiting checker verification) |
"Primary" marks the governing clause for this exercise; "contextual" marks related clauses; "supporting" marks the design-method or data source outside the CDC. A CDC chapter mapping does not mean the CDC contains the equation used.
Prerequisites: B10 BS 8110 — continuous one-way slab (Table 3.12) · Topics: Reinforced concrete
Lesson
Lesson in preparation. No content is published until it has been written and reviewed.
Calculator
Purpose: Rectangular slab panel spanning in two directions: moments, steel, span/depth, support shears and corner torsion steel.
Model: Restrained panels: βsy = (24 + 2Nd + 1.5Nd²)/1000; γ = (2/9)[3 − √18 (lx/ly)(√(βsy + β2) + √(βsy + β4))]; √γ = √(βsx + β1) + √(βsx + β3); support coefficients = 4/3 × span coefficient at continuous edges. Simply supported: αsx = r⁴/[8(1 + r⁴)], αsy = r²/[8(1 + r⁴)], r = ly/lx. Shears from Table 3.15 coefficients: Σβvx + (lx/ly)Σβvy = 4/3, split 0.6/0.4 between continuous and discontinuous edges.
Units: N, mm, kN, kNm; stresses in N/mm² Ranges: fcu 25–50 N/mm²; fy 250 / 460 / 500; βb 0.7–1.0
Equations: msx = βsx n lx², msy = βsy n lx² (restrained); msx = αsx n lx² (simple) ; vs = βv n lx (kN/m) ; Corner torsion steel: ¾ Asx (both edges discontinuous) or ⅜ Asx (one edge), top and bottom each way over lx/5
Clauses: 3.5.3.3 & Table 3.13 (eqs 12–13); 3.5.3.4–3.5.3.5 & Table 3.14 (eqs 14–18, torsion steel 3.5.3.5); 3.5.3.7 & Table 3.15 (eqs 19–20); 3.4.4.4; Table 3.25; 3.4.6 / 3.5.7 (span/d on the short span); 3.5.5 (shear); 3.12.11.2.7
© 2026 QP Academy. Original calculation software implementing BS 8110-1:1997 (+A1, A2, A3). BS 8110 is WITHDRAWN (superseded by BS EN 1992-1-1 and, in Singapore, SS EN 1992-1-1). For education and for checking legacy designs only — not for new design submissions.
Not covered: ly/lx > 2 (design as one-way); Panels with unequal adjacent spans or loads beyond 3.5.3.5; Openings, point loads, cantilevered edges; Shear reinforcement; deflection enhancement by extra steel
Version 0.1.0 Draft
EDUCATION PREVIEW — NOT YET INDEPENDENTLY CHECKED. Education preview: this calculator has not yet been independently checked by an engineer. Use for learning only — not for engineering use. Outputs are stamped and must not be used for engineering work.
Excel workbook
The workbook is available with the calculator once this version is released.
Exercises
Assessment in preparation.