DESIGN SPECIFICATIONS FOR HIGHWAY BRIDGES - IISEE

k hg : Design horizontal seismic coefficient at the ground surface for Level 2
Earthquake Ground Motion specified in Section 6.4.3
σv: Total overburden pressure (kN/m 2 )
σ’v : Effective overburden pressure (kN/m 2 )
x : Depth from the ground surface (m)
γt1: Unit weight of soil above the ground water level (kN/m 3 )
γt2: Unit weight of soil below the ground water level (kN/m 3 )
γ’t2: Effective unit weight of soil below the ground water level (kN/m 3 )
hw: Depth of the ground water level (m)
(3) Cyclic triaxial shear stress ratio
Cyclic triaxial shear stress ratio RL shall be calculated by Equation (8.2.9).
R
L
0.0882
0.0882
N
N
a
a
/1.7
/1.7 1.6
10
6
・N
a
14
4.5
( N
a
14)
(14 N )
a
・・・・・・・・・・・・・・・・・・・・・ (8.2.9)
where
Na = c 1
N1 + c 2
・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (8.2.10)
N1 =170N / (σ’v +70 )・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (8.2.11)
1 ( 0%≦FC < 10% )
c1 = (FC +40) / 50 ( 10%≦FC < 60% ) ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・ (8.2.12)
FC / 20-1 ( 60%≦FC )
0 (0%≦FC