Seismic Load for Design Criteria According to Egyptian Code of Practice for Calculating Loads and Forces on Structures and Building

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Seismic Load for Design Criteria
According to Egyptian Code of Practice for Calculating Loads
and Forces on Structures and Building
Egyptian Codes for calculated loads and forces on structure and building No (201 /
2008 & 201/2011) include three chapters for calculate Seismic load as Following:-
 Chapter (8) : Seismic Loads on Building.
 Chapter ( 9 ) : Seismic Loads on Bridges.
 Chapter (10) : Seismic Loads on tanks.
Egyptian Codes for loading Construction and building Accept to Estimate Seismic
loads by Their Methods as following:-
 Simplified Modal Response Spectrum Methods ((Equivalent static
Loads)).
 Multi-Modal Response Spectrum Method.
 Dynamic analysis ( Time – History Method )
The Egyptian Code concentrated on Elastic Response Spectrum method and explained
it with more details
Elastic Response Spectrum
The Main aim of Elastic Response Spectrum is drawing Curves between two
EC201/2011 & 201/2008 have been divided A.R.E (Egypt) to Two Type for
Horizontal Elastic Response Spectrum as following below figure.
Horizontal Elastic Response Diagram For Type ( I ) to all A.R.E

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Horizontal Elastic Response Diagram For Type ( II ) to all A.R.E For all Area
beside Meridian sea with alignment for 40 KM
The equation use to calculation Elastic Response Spectrum as following table:-
Region Horizontal Elastic Response Spectrum Vertical elastic Response spectrum
0 ≤ T ≤ TB
𝑆 𝑒(𝑇) = 𝑎 𝑔 ∗ 𝛾1 ∗ 𝑆 ∗ [1 +
𝑇
𝑇𝐵
(2.5𝜂 − 1)] 𝑆 𝑣𝑒(𝑇) = 𝑎 𝑣𝑔 ∗ 𝛾1 [1 +
𝑇
𝑇𝐵
(3𝜂 𝑣 − 1)]
TB ≤ T ≤ TC 𝑆 𝑒(𝑇) = 2.5 𝑎 𝑔 ∗ 𝛾1 ∗ 𝑆 ∗ 𝜂 𝑆 𝑣𝑒(𝑇) = 3𝑎 𝑣𝑔 ∗ 𝛾1 ∗ 𝜂 𝑣
TC ≤ T ≤ TD
𝑆 𝑒(𝑇) = 2.5 𝑎 𝑔 ∗ 𝛾1 ∗ 𝑆 ∗ 𝜂 ∗ [
𝑇𝐶
𝑇
] 𝑆 𝑣𝑒(𝑇) = 3 𝑎 𝑣𝑔 ∗ 𝛾1 ∗ 𝜂 𝑣 ∗ [
𝑇𝐶
𝑇
]
TC ≤ T ≤ 4 s
𝑆 𝑒(𝑇) = 2.5 𝑎 𝑔 ∗ 𝛾1 ∗ 𝑆 ∗ 𝜂 ∗ [
𝑇𝐶 ∗ 𝑇 𝐷
𝑇2 ] 𝑆 𝑒(𝑇) = 3 𝑎 𝑣𝑔 ∗ 𝛾1 ∗ 𝜂 𝑣 ∗ [
𝑇𝐶 ∗ 𝑇 𝐷
𝑇2 ]
Where:
Se (T) Elastic Horizontal Response Spectrum
S ve (T) Elastic Vertical Response Spectrum
T Vibration Period,
ag Designed Ground Acceleration,
avg Vertical Designed Ground Acceleration

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Ɣ1 Importance Factor
TB, TC, and TD Limits depending on the soil type,
η Design Damping factor depending on the type of structure (RC),
ηv Vertical Design Damping factor depending on the type of structure
(RC),
S: Soil factor.
EC201/2011 & 201/2008 consider a table to gets vertical factor which can draw
the vertical elastic Response diagram as following Table :
Spectrum avg / ag TB Tc TD
Type I 0.45 0.05 0.15 1.0
Type II 0.9 0.05 0.15 1.0
Note: - Vertical acceleration isn’t depend on type of soil
Step 1 :- calculate ground acceleration (ag)
According to the assumed zones, the designed ground acceleration, ag, will vary
according to the EC 201/2008 & EC201/2011 . the following table restated the values
of designed ground acceleration, ag, for the Five seismic zones shown on the
following map.
Table 4.1 Designed Ground Acceleration, ag.
Zone No. ag
1 0.10 g
3 0.15 g
5 0.25 g
Assiut on Zone No 1

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cal
Step 2 : Calculate importance factor Ɣ1
Its depend on the importance of structure and range of requirement on Natural
disaster which The EC201/2008 & EC 201/2011 classified it on the following table:-
:-

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Importance
Group
Structure Ɣ1
I
Include structure which should be work with full
efficiency at Emergency purpose as :-
(Hospitals – Firefighting Centers – Power plants –
Police station …….etc. )
1.4
II
Structure which should have earthquake resistance and
the damage on it will cause to lose of Human life's :
(Schools and universities, Mosque and churches,
Culture Centers and Tanks and Silos …..etc. ) 1.2
III Ordinary Structure 1.0
IIII Temporary Structure 0.8
Step 3 :- calculate Soil Factors (S)
Geotechnical Report should include there value for estimate classification of soil. It is
as following:-
NSPT : Number of Standard penetration Test ( No. Per 30 cm )
Cu : shear strength for soil from unconfined Test (KN/m2
)
VS,30 : Shear Waves Velocity (m/Sec )
Group Description NSPT Cu VS,30
A Rock ---- ------ > 800
B Dense Soil > 50 >250 From 800 to 360
C Medium Soil From 15 to 50 From 70 to 250 From 360 to 180
D Weak Soil <15 <70 <180
E* Very weak Soil __________ _________ __________
E* added on EC201/2011
After we know soil classification can Know S factor according to this below table :

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Type I
Subsoil Class S TB TC TD
A 1.0 0.05 0.05 1.2
B 1.35 0.05 0.25 1.2
C 1.5 0.10 0.25 1.2
D 1.8 0.10 0.3 1.2
E* 1.6 0.05 0.25 1.2
Type II
Subsoil Class S TB TC TD
A 1.0 0.15 0.4 2.0
B 1.2 0.15 0.5 2.0
C 1.15 0.20 0.6 2.0
D 1.35 0.20 0.8 2.0
E* 1.4 0.15 0.5 2.0
Note: it should be modified Soil factor if the structure is on calf
Step 4 : calculate Damping Factor, η & ηv
According the following Table:-
Structure Type η ηv
Steel structure with welded connection 1.20 1.0
Steel structure with bolted connection 1.50 0.75
Reinforcement Concrete 1.0 0.7
Prestressed concrete 1.05 0.75
Shear wall 0.95 0.65