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Code Name

Iranian Code for Seismic Resistance Design of Buildings

Issued by

Building and Housing Research Center


Horizontal Base Shear

V = CW

  V : Base shear force (total seismic lateral forces in direction under consideration)

  W : Total weight of the building (total dead load and weight of fixed installations) plus some of the
        live load

  C : Seismic coefficient obtained from Relation (1)

C = ABI/R                                              (1) 

          A : Design base acceleration (in relation to gravity acceleration g) (See Table 1)

          B : Response coefficient of the building obtained from the design response spectrum (See Fig.2),
               which is determined in accordance with Relation (2)

                        B = 2.0(T/T0)2/3                             (2)

                        T : Fundamental natural period of vibration of the building

                       T0 : Figure which is given according to the type of soil (See Table 2)

          I : Importance factor (See Table 4)

         R : Behavior coefficient of the building (See Table 6)

         The maximum value of B is taken to be equal to 2.0 and the minimum to 0.6.

The C value adopted shall in no case be less than 10 % of the design base acceleration.