After this chapter, you should be able to
- Distinguish local bearing from global wall compression.
- Calculate A_b, A_ef, stress and utilisation.
- Recognise edges and openings that limit spread.
- Decide when a padstone or spreader is required.
- Carry the reaction into the wall-below check.
4.1 Purpose and workflowSource §4.1
A masonry wall may pass its global vertical check yet fail immediately below a small beam end, bearing plate or lintel reaction. Local bearing is therefore a separate concentrated-compression check.
- Calculate the design concentrated load N_Edc.
- Define the actual bearing area.
- Estimate effective spread area and edge restrictions.
- Select β only where justified.
- Check direct bearing.
- If needed, size a spreader and check the wall below.
4.2 NotationSource §4.2
| Symbol | Meaning | Typical unit |
|---|---|---|
| N_Edc | Design concentrated load | kN |
| N_Rdc | Design concentrated-load resistance | kN |
| A_b | Actual loaded bearing area | mm² |
| A_ef | Effective area after load spread | mm² |
| l_c, w_c | Bearing length and width | mm |
| f_d | Design compressive strength | N/mm² |
| β | Concentrated-load enhancement factor | — |
| e_c | Load eccentricity from wall centreline | mm |
4.3 Local bearing versus global compressionSource §4.3
- Global compression
- Checks the wall strip under total vertical load after slenderness and eccentricity effects: N_Ed ≤ N_Rd.
- Local bearing
- Checks masonry immediately beneath the limited support area: N_Edc ≤ N_Rdc.
4.4 Sources of concentrated loadsSource §4.4
- Beam-end reactions from floors and roofs.
- Lintel reactions beside openings.
- Padstones, spreaders and bearing plates.
- Brackets, corbels and temporary-works reactions.
- Plant or transfer-member reactions.
4.5 Actual loaded area and effective areaSource §4.5
Use the actual contact dimensions beneath the supported member.
The adopted model must stop at wall ends, openings, movement joints, chases and unsupported edges.
Keep direct contact area separate from the effective spread area.
4.6 Concentrated-load resistance and βSource §4.6
Enhancement represents confinement and load spread but is not automatic.
Teaching form recorded by the source for WE-05.
Prevents unlimited enhancement.
4.7 Edges, openings and lintel zonesSource §4.7
- Do not spread load through an opening or movement joint.
- Check the local pier beside an opening.
- Use one-sided spread where bearing is near an edge.
- Show an edge/opening warning even when the numerical resistance appears adequate.
4.8 Padstones and spreadersSource §4.8
A padstone or spreader increases contact length and transfers reaction into a larger masonry zone. It introduces its own material, bearing, bending, shear and detailing checks; do not stop after placing it in the model.
4.9 Wall check below a concentrated loadSource §4.9
| Check | Purpose |
|---|---|
| Effective length at mid-height | Defines how much wall length receives the spread load. |
| Distributed local reaction | Converts the reaction into a line load at the lower check. |
| Global vertical resistance | Checks N_Ed ≤ N_Rd in the wall below. |
| Eccentricity and slenderness | Confirms the downstream load path remains acceptable. |
4.10 Concentrated Load / Padstone CalculatorSource §4.10
Concentrated Load / Padstone Calculator
Calculate the design reaction, areas, source enhancement factor, direct bearing resistance and spreader stress while preserving edge/detail warnings.
- Inputs
- G_k · Q_k · Action factors · Bearing dimensions · Wall thickness · f_d · Clear height · Edge distance · Spreader length
- Outputs
- N_Edc · A_b · A_ef · β · N_Rdc · Direct utilisation · Spreader stress
- Status states
- Pass · Fail—spreader review required · Invalid input
- Validation
- Approved against the supplied worked-example results; project-specific verification remains required
Concentrated Load / Padstone Calculator
Approved educational implementation reproducing the supplied source example.
Direct bearing fails; review a padstone or spreader and complete all follow-on checks.
- Design concentrated load
- 35.25 kN
- Actual / effective area
- 10000 / 127169 mm²
- Enhancement β
- 1.34
- Direct resistance
- 25.59 kN
- Direct utilisation
- 1.38
- Stress below spreader
- 0.78 N/mm²
Calculation trail
N_Edc = 1.35G_k + 1.50Q_k = 35.25 kNA_b = 10000 mm²l_efm = 1272 mm; A_ef = 127169 mm²β = min(1.49, 1.34) = 1.34N_Rdc = βA_bf_d = 25.59 kN
4.11 WE-05 — Beam bearing / padstone checkSource §4.11
WE-05 · Chapter 04 local bearing
Check a concentrated beam reaction near the end of a 100 mm aggregate-concrete blockwork wall. If direct bearing fails, adopt the source 450 × 225 × 100 mm concrete spreader and check the wall below.
- Material
fb = 7.3(1.0)(1.38) = 10.07; fk = 0.75(10.070.7)(4.00.3)
fk = 5.73; fd = 1.91 N/mm2 - Suitability
hef/tef = 2500/100 = 25; ec = 10 mm ≤ t/4 = 25 mm
Slenderness and eccentricity source checks pass - Design load
NEdc = 1.35(15) + 1.50(10)
35.25 kN - Areas
Ab = 100(100) = 10,000 mm2; lefm = 100 + 1250tan30° + 450 = 1272 mm
Aef = 127,200 mm2 - Enhancement
βinit = 1.49; βmax = 1.34
Adopt β = 1.34 - Direct bearing
NRdc = 1.34(10,000)(1.91)/1000
25.58 kN < 35.25 kN · FAIL - Spreader
σd,sp = 35.25×1000/(450×100)
0.78 N/mm2 ≤ 1.5fd = 2.86 · PASS - Wall below
Nmd = 21.66 kN/m; source Annex G route gives Φm = 0.40
NRd = 76.08 kN/m ≥ 21.66 · PASS
Result. Direct bearing on 100 × 100 mm fails. The source-adopted spreader passes its recorded stress check and the wall below passes the source mid-height check; the spreader itself still requires complete project design.
4.12 Chapter summarySource §4.12
Key points
- Global wall resistance does not prove local bearing.
- Keep A_b and A_ef separate and respect discontinuities.
- Use β only when its geometry and eccentricity assumptions are satisfied.
- If direct bearing fails, design the spreader and recheck the wall below.
Source references recorded by the supplied chapter
- EN 1996-1-1 §§6.1.2 and 6.1.3; Figure 6.2 concept
- EN 1990 Equation 6.10 action combination
- Updated interactive book Chapter 04 and supplied worked-example document