ABSTRACT
The compu ta t i on of ea r thquake loads acting on the s t ructure is given in terms of response sepctra in mos t of the current codes.
Specification of base shear-equivalent static approach . This specifies first the procedure and necessary numerical da t a for the computa t ion of base shear and bending m o m e n t a t each floor either directly or th rough the compu ta t ion of the intertial forces on the s tructure. Take the former as an example; the commonly used format is as follows:
Hor izonta l base shear Vo = cnW (14.1a)
a = Z / S C p ( r , Qikb (14.1b)
where a is the hor izonta l ea r thquake load coefficient or ea r thquake coeffi cient; k0 = a/g is the basic ea r thquake coefficient and a the hor izonta l acceleration of g round mot ion . The basic coefficient is modified by a seismic zoning coefficient Z and the p roduc t Zk0 is the zone ea r thquake coefficient. / is the impor tance factor of the structure; C is the s t ructural coefficient; S is the site effect factor; (3(7, Q is the design response spectrum, a function of the na tura l per iod T and damping ra t io q of the s t ructure; W is the weight of s t ructure, including the total dead load and par t ia l live load. The damping ra t io q of an ord inary s t ructure is usually taken as 0.05.
