Response spectrum analysis of a shear frame structure by using MATLAB

A shear frame may be defined as a structure in which there is no rotation of a horizontal section at the level of the floor. In this respect the deflected frame will have many of the features of a cantilever beam that is deflected by shear forces, Hence the name Shear frame is given to those frames. To accomplish such deflection in frame, it is assume that: (1) the total mass of the structure is concentrated at the levels of the floors; (2) the beams on the floor are infinitely rigid as compared to the columns; and (3) the deformation of the structure is independent of the axial forces present in the columns. These assumptions transform the problem from a structure with an infinite number of degree of freedom (due to the distributed mass) to a structure which has only as many degrees as it has lumped masses at the floor levels. This paper is concerned with the response spectrum analysis of six stories shear frame with six degrees of freedom i.e. six horizontal displacement at the floor levels. From the analysis it concluded that, the first mode shape is most important one, because 86.96%, of Mass will respond to ground motion, when only 8.91% of mass will respond in the second. Mode shape, also the only first-two mode shapes will be adequate to insure that more than 90% of the mass will vibrate responding to ground motion