Code Name

National Standards of the People's Republic of China

Code for Seismic Design of Buildings (GB50011-2001)

(Issued: July.20, 2001, Actualized: Jan. 1, 2002)

Issued by

Ministry of Construction

Revision

TJ11-74 (1974), TJ11-78 (1978), GBJ11-89 (1989), GB50011-2001 (2001)

Horizontal Seismic
Forces (Based Shear Method)

F_Ek :  standard value of the total horizontal seismic action of the structure

G_eq :  Total equivalent seismic weight of a building. The repetitive value of the total gravity load shall be used when the structures is modeled as a single-mass system; when the structure is modeled as multi-mass system, 85% of the representative of the total gravity load may by used. ( Table 1)

ƒ¿₁:   horizontal seismic effective coefficient corresponding to the fundamental period of the structure (Figure 1)

ƒ¿ =Seismic coefficient

T  =Natural period of structure

T_g  = Design Characteristic Period of Ground Motion (Table 2).

ƒ¿_max  = Maximum value of the seismic coefficient( Table 3)

For 0.1<T< T_g , ƒ¿=ƒ¿_max

      for  T_g<T< 5T_g

  attenuation index for T_g<T< 5T_g

  damping ratio

  for  5T_g<T< 6.0

 slope adjustment coefficient for T_g<T< 5T_g, it equal to 0.0 when it less than 0.0

 damping adjustment coefficient, it equal to 0.55 when it less than 0.55

F_i:   standard value of horizontal seismic action applied on mass (Figure 2)

G_i, G_j: representative values of gravity load concentrated at the masses of i and j, taken as the combination of dead load and live load (Table 1)

H_i, H_j: calculated height of masses i and j from the base of building respectively

ƒÂ_n:  additional seismic action coefficient at the top level of building (Table 4)

ĢF_n: Additional seismic force action at the top of building