Lateral Systems

EN 1998-1 lateral force method · shear wall force distribution · RC wall design

Seismic base shear (lateral force method)EN 1998-1 3.2.2.5, 4.3.3.2

agR (g)Importance γISpectrum typeGround typeBehaviour factor qCtStoreysStorey height (m)Seismic weight / storey (kN)

T1	Ct H^(3/4)	0.688 s
ag = γI agR		0.200 g
Sd(T1)		0.1118 g
λ		0.85
Total weight		18000 kN
Base shear Fb	Sd(T1) W λ	1711 kN
Fb / W		0.0950

Storey	z (m)	Fi (kN)	Vi (kN)
6	19.2	488.8	488.8
5	16.0	407.3	896.2
4	12.8	325.9	1222.0
3	9.6	244.4	1466.4
2	6.4	162.9	1629.4
1	3.2	81.5	1710.8

3D view: walls and seismic storey forces

Distribution of storey shear to wallsrigid diaphragm, one direction

Storey shear V (kN)Centre of mass x (m)Building width (m)

Wall	Direct (kN)	Torsion (kN)	Design (kN)
W1	342.9	184.2	527.1
W2	342.9	23.0	365.9
W3	514.3	207.2	721.5

Centre of rigidity x = 13.71 m · design eccentricity e = |xCM − xCR| + 0.05 B = 3.91 m

RC shear wall designEN 1992-1-1 6.2.3, 9.6

Length lw (mm)Thickness tw (mm)NEd (kN)MEd (in plane) (kNm)VEd (kN)ConcreteVertical Ø (each face) (mm)Vertical spacing (mm)Horizontal Ø (mm)Cover (mm)

National Annex (partial factors)

Wall design passes · boundary: 2 × 2Ø12 per end · ρv = 0.37%

Checks

OKFlexure + axial (N–M) MRd 3470 ≥ MEd 2500 kNm with 2×2Ø12 end bars
OKVertical steel ≥ 0.002 Ac 2809 ≥ 1500 mm² (EN 1992-1-1 9.6.2)
OKVertical bar spacing 200 ≤ 400 mm
OKShear (VEd ≤ VRd,max) 400 ≤ 2185 kN (cot θ = 2.50)
OKHorizontal steel Ø10 each face @ 400 mm (ρh,min = 0.0010)

Wall with door/window openings: pier designsimplified pier model

Opening widths (m), comma separatedOpening height (m)Concrete E (GPa)

Uses the wall length, thickness, loads and materials from the wall design above, and the storey height from the seismic section. Openings are spaced evenly.

Lateral stiffness is 89% of the solid wall · 2 piers

Pier	Length	Share	VEd	NEd	MEd	Boundary bars
P1	1.00 m	50%	200 kN	750 kN	210 kNm	2 × 2Ø12	OK
P2	1.00 m	50%	200 kN	750 kN	210 kNm	2 × 2Ø12	OK

Piers act in parallel over the opening height (fixed-fixed, flexure + shear stiffness) and in series with the solid wall above. Coupling beams over the openings are not designed: check them with the beam tool.

Scope: regular buildings, lateral force method (T1 ≤ min(4 TC, 2 s), no significant higher modes), no ductile detailing (DC) rules beyond minimum steel, wall distribution for one direction only, no coupling or openings. Results are an aid only and must be verified by a qualified, licensed engineer before use. National Annex presets are recommended values and must be checked against the official documents.