3 · Two-Way Slab Design
Restrained panel, Annex D · Case 1 — Interior panel — all four edges continuous
Shorter span, lx
4.000m
Longer span, ly
6.000m
ly / lx
≤ 2.0 for two-way action
1.500OK
Effective depth, short span dx
D − cover − ø/2
174mm
Effective depth, long span dy
D − cover − ø_main − ø_dist/2
164mm
Table 26 row for Case 1
| ly/lx | 1.00 | 1.10 | 1.20 | 1.30 | 1.40 | 1.50 | 1.75 | 2.00 |
|---|---|---|---|---|---|---|---|---|
| αx (−) support | 0.032 | 0.037 | 0.043 | 0.047 | 0.051 | 0.053 | 0.060 | 0.065 |
| αx (+) midspan | 0.024 | 0.028 | 0.032 | 0.036 | 0.039 | 0.041 | 0.045 | 0.049 |
αx (−)Table 26
table value, exact ly/lx
0.0530
αx (+)
table value, exact ly/lx
0.0410
αy (−)
constant for all ly/lx
0.0320
αy (+)
constant for all ly/lx
0.0240
Mx (−) at continuous short-span edge
αx(−)·wu·lx² = 0.0530 × 16.50 × 4.000²
13.992kN·m/m
Mx (+) short-span midspan
αx(+)·wu·lx²
10.824kN·m/m
My (−) at continuous long-span edge
αy(−)·wu·lx²
8.448kN·m/m
My (+) long-span midspan
αy(+)·wu·lx²
6.336kN·m/m
Midspan (positive moment)
Ru = Mu/(b·dx²)
0.358N/mm²
pt required
fck/(2fy)·[1 − √(1 − 4.598Ru/fck)]·100
0.0836%
Design pt (≥ 0.12 % of b·D)Cl. 26.5.2.1
0.1379%
Ast required
240mm²/m
Spacing required
1000·Ab/Ast,req
471.2mm
Ast provided
754mm²/mOK
Support (negative moment) — top steel
Ast required
240mm²/m
Spacing required
471.2mm
Ast provided at the same spacing
754mm²/mOK
Midspan (positive moment)
Ru = Mu/(b·dy²)
0.236N/mm²
Design pt
0.1463%
Ast required
240mm²/m
Ast provided
251mm²/mOK
Support (negative moment) — top steel
Ast required
240mm²/m
Ast provided
251mm²/mOK
Case 1 interior panel — all edges continuous, so no corner torsion steel is required.
Design shear, Vu
0.5·wu·lx/2 — short span share
16.500kN/m
τv = Vu/(b·dx)Cl. 40.1
0.095N/mm²
100·Ast/(b·dx)
0.433
τcTable 19
0.461N/mm²
kCl. 40.2.1.1
1.20
k·τc
0.553N/mm²
Verdict
No shear reinforcement required (Cl. 40.2.3)OK
Span used for the check
shorter span lx
4.000m
Basic l/dCl. 23.2.1
26
fs
0.58·fy·(Ast,req/Ast,prov)
92.3N/mm²
Modification factorFig. 4
2.0000
Allowable l/d
52.000
Provided l/d
lx / dx
22.989OK
| Location | Bar | Spacing | Ast req. | Ast prov. | Status |
|---|---|---|---|---|---|
| Short span — bottom, midspan | ø12 | 150 mm c/c | 240 mm²/m | 754 mm²/m | OK |
| Short span — top, at support | ø12 | 150 mm c/c | 240 mm²/m | 754 mm²/m | OK |
| Long span — bottom, midspan | ø8 | 200 mm c/c | 240 mm²/m | 251 mm²/m | OK |
| Long span — top, at support | ø8 | 200 mm c/c | 240 mm²/m | 251 mm²/m | OK |