Name
Date
Prepared by Checked by Approved by
Seismic Load Design Calculation per BS EN 1998-1 & 1998-6 Reference
Calculation
Ground type
Output
D
=
(deposits of loose-to-medium cohesionless soil...)
Soil parameters: S TB TC TD
= = = =
1.35 0.20 0.80 2.00
Viscous damping ratio, ξ
=
5
Damping correction factor, η = = = =
s s s
%
√[ 10 / (5 + ξ) ] √[ 10 / ( 5 1.00 but 1.00
+ 5 )] ≥ 0.55
Horizontal Elastic Response Spectrum is as defined and plotted below: 0 ≤ T ≤ TB :
Se (t) = ag S [ 1 + ( T / TB ) ( η 2.5 - 1 ) ]
TB ≤ T ≤ TC :
Se (t) = ag S η 2.5
TC ≤ T ≤ TD :
Se (t) = ag S η 2.5 ( TC / T )
TD ≤ T ≤ 4s :
Se (t) = ag S η 2.5 ( TC TD / T2 )
Response Spectrum Curve Elastic Response Spectrum, Se(t) (g)
0.40 Se(t) = agSη2.5
0.35 0.30 0.25 0.20
Elastic Spectrum
0.15
Design Spectrum
0.10 0.05 0.00 0.00
0.20
0.80
2.00
(TB)
(TC)
(TD)
4.00
Vibration Period, T (s)
aa
Page 2 of 17
Name
Date
Prepared by Checked by Approved by
Seismic Load Design Calculation per BS EN 1998-1 & 1998-6 Reference
Calculation
Output
3.0 Criteria for Regularity in Plan For a building to be categorised as being regular in plan, it shall satisfy all the conditions listed in the following paragraphs:
Regularity compliance
a. With respect to the lateral stiffness and mass distribution, the building structure shall be approximately symmetrical in plan with respect to two orthogonal axes.
Yes
b. The plan configuration shall be compact, i.e., each floor shall be delimited by a polygonal convex line. If in plan set-backs (re-entrant corners or edge recesses) exist, regularity in plan may still be considered as being satisfied, provided that these setbacks do not affect the floor in-plan stiffness and that, for each set-back, the area between the outline of the floor and a convex polygonal line enveloping the floor does not exceed 5% of the floor area.
Yes
c. The in-plan stiffness of the floors shall be sufficiently large in comparison with the lateral stiffness of the vertical structural elements, so that the deformation of the floor shall have a small effect on the distribution of the forces among the vertical structural elements. In this respect, the L, C, H, I, and X plan shapes should be carefully examined, notably as concerns the stiffness of the lateral branches, which should be comparable to that of the central part, in order to satisfy the rigid diaphragm condition. The application of this paragraph should be considered for the global behaviour of the building.
Yes
d. The slenderness λ = Lmax/Lmin of the building in plan shall be not higher than 4, where Lmax and Lmin are respectively the larger and smaller in plan dimension of the building, measured in orthogonal directions.
Yes
e. At each level and for each direction of analysis x and y, the eccentricity eo and the torsional radius r shall be in accordance with the two conditions below, which are expressed for the direction of analysis y:
Yes
eox ≤ 0,30 rx
and
rx ≥ ls
where,
eox is the distance between the centre of stiffness and the centre of mass, measured along the x direction, which is normal to the direction of analysis considered; rx is the square root of the ratio of the torsional stiffness to the lateral stiffness in the y direction (“torsional radius”); and ls is the radius of gyration of the floor mass in plan (square root of the ratio of (a) the polar moment of inertia of the floor mass in plan with respect to the centre of mass of the floor to (b) the floor mass). Hence, building is categorised as regular in plan.
aa
Page 3 of 17
Name
Date
Prepared by Checked by Approved by
Seismic Load Design Calculation per BS EN 1998-1 & 1998-6 Reference
Calculation
Output
4.0 Criteria for Regularity in Elevation For a building to be categorised as being regular in elevation, it shall satisfy all the conditions listed in the following paragraphs:
Regularity compliance
a. All lateral load resisting systems, such as cores, structural walls, or frames, shall run without interruption from their foundations to the top of the building or, if setbacks at different heights are present, to the top of the relevant zone of the building.
Yes
b. Both the lateral stiffness and the mass of the individual storeys shall remain constant or reduce gradually, without abrupt changes, from the base to the top of a particular building.
Yes
c. In framed buildings the ratio of the actual storey resistance to the resistance required by the analysis should not vary disproportionately between adjacent storeys.
No
Hence, building is categorised as non-regular in elevation.
5.0 Criteria for Structural Regularity Table A: Recommended Structural Analysis Approach Allowed Simplification
Regularity
Model
Method of Analysis
Behaviour Factor
Plan
Elevation
Yes
Yes
Planar
Lateral force **
Reference value
Yes
No
Planar
Modal
Decreased value *
No
Yes
Spatial
Lateral force **
Reference value
No
No
Spatial
Modal
Decreased value *
(Linear-elastic analysis)
(for linear analysis)
Min. applicability
Note: * basic behaviour factor, q o shall be reduced by 20% (see Table C for reduced value) ** applicable only if natural period, T1 ≤ 4T C & 2s
6.0 Category of Seismicity ag
=
0.1125 g
ag S
= =
0.1125 x 1.35 0.15 g
If ag ≤ 0.04g (or) agS ≤ 0.05g, the site is categorised as 'very low seismicity'.
NO
If ag ≤ 0.08g (or) agS ≤ 0.10g, the site is categorised as 'low seismicity'.
NO
If ag > 0.08g (and) agS > 0.10g, the site is categorised as 'high seismicity'.
YES
In this case, the site falls under 'high seismicity' category.
aa
Page 4 of 17
Name
Date
Prepared by Checked by Approved by
Seismic Load Design Calculation per BS EN 1998-1 & 1998-6 Reference
Calculation
Output
7.0 Ductility Class and Behaviour Factor - for Concrete Buildings Ductility class
=
DCM (Ductility Class Medium)
Behaviour factor, q
=
qo kw
Basic behaviour factor, qo
=
Refer Table B if regular in elevation (or) Table C if non-regular in elevation
Wall factor, kw
=
1.0 (conservatively)
Table B: Basic value of behaviour factor, qo, for systems REGULAR in elevation DCM Structural Type
Frame system, dual system, coupled wall system
DCH
Regular
Non-regular
Regular
Non-regular
in plan αu/α1 qo
in plan αu/α1 qo
in plan αu/α1 qo
in plan αu/α1 qo
-
3αu/α1
-
3αu/α1
-
4.5αu/α1
-
4.5αu/α1
1.10
3.30
1.05
3.15
1.10
4.95
1.05
4.73
1.20
3.60
1.10
3.30
1.20
5.40
1.10
4.95
1.30
3.90
1.15
3.45
1.30
5.85
1.15
5.18
1.30
3.90
1.15
3.45
1.30
5.85
1.15
5.18
1.20
3.60
1.10
3.30
1.20
5.40
1.10
4.95
-
-
-
-
-
4.0αu/α1
-
4.0αu/α1
-
3.00
-
3.00
1.00
4.00
1.00
4.00
-
3.00
-
3.00
1.10
4.40
1.05
4.20
-
2.00 1.50
-
2.00 1.50
-
3.00 2.00
-
3.00 2.00
a) Frame or frame-equivalent dual system - one-storey buildings - multistorey, one-bay frames - multistory, multi-bay frames - frame-equivalent dual structures b) Wall or wall-equivalent dual system - wall-equivalent dual, or coupled wall systems Uncoupled wall system - wall systems with only two uncoupled wall per horizontal direction - other uncoupled wall systems Torsionally flexible system Inverted pendulum system
aa
Page 5 of 17
Name
Date
Prepared by Checked by Approved by
Seismic Load Design Calculation per BS EN 1998-1 & 1998-6 Reference
Calculation
Output
Table C: Basic value of behaviour factor, qo, for systems NON-REGULAR in elevation DCM Structural Type
DCH
Regular
Non-regular
Regular
Non-regular
in plan αu/α1 qo
in plan αu/α1 qo
in plan αu/α1 qo
in plan αu/α1 qo
Frame system, dual system, coupled wall system a) Frame or frame-equivalent dual system - one-storey buildings - multistorey, one-bay frames - multistory, multi-bay frames - frame-equivalent dual structures
-
2.64
-
2.52
-
3.96
-
3.78
-
2.88
-
2.64
-
4.32
-
3.96
-
3.12
-
2.76
-
4.68
-
4.14
-
3.12
-
2.76
-
4.68
-
4.14
-
2.88
-
2.64
-
4.32
-
3.96
-
2.40
-
2.40
-
3.20
-
3.20
-
2.40
-
2.40
-
3.52
-
3.36
2.40 1.60
-
2.40 1.60
b) Wall or wall-equivalent dual system - wall-equivalent dual, or coupled wall systems Uncoupled wall system - wall systems with only two uncoupled wall per horizontal direction - other uncoupled wall systems
1.60 1.60 Torsionally flexible system Inverted pendulum system 1.20 1.20 Note: Shaded area denotes applicable q ̥ values
aa
Page 6 of 17
