Influence of Earthquake according to JTJ 004-89
Only horizontal seismic force is considered according to JTJ 004-89.
Seismic force on structure
Seismic force acting on structure is provided by (Art. 3.1.5):
seismic force acting at the center of gravity of the wall above the ith cross section [kN/m]
coefficient of horizontal seismic acceleration
weight of the structure above the ith cross section [kN/m]
comprehensive influence factor, usually it's 0.25
distribution coefficient of horizontal earthquake along the wall
Recommended value of distribution coefficient ψiw (Tbl. 3.1.5):
Wall Height [m]
Calculation diagram for ψiw
Highway, A class and B class motorway
C class and D class motorway
H ≤ 12
ψiw = 1
ψiw = 1
H > 12
ψiw = 1
ψiw isn't considered when H ≤ 12 m which means parameter a and b don't work when H ≤ 12 m. a is the top value of the distribution map and b is the bottom value of the distribution map.
Seismic earth pressure
When computing seismic earth pressure, Coulomb theory is used and unite weight of soil γ, internal friction angle of soil φ and angle of friction structure-soil δ is replaced by γ / cos θ, sdasdasd φ - θ, δ + θ, where θ is seismic angle (Art. 3.1.6).
Seismic angel θ is determined by different option of .
Cz.is a little different from the or by reducing the water influence using comprehensive influence factor
Seismic bearing capacity of subsoil
Seismic bearing capacity of subsoil is provided by (Art. 2.2.1):
seismic bearing capacity of subsoil
adjusting coefficient for seismic bearing capacity
characteristic value of bearing capacity which has been modified by the geometry of foundation
The above formula is as same as Art. 4.2.3 in GB 50011-2010 (Code for seismic design of buildings). Suggested values of ξa by different standards can be found .