08-10-2014, 04:07 PM
A displacement and ductility based design procedure (DDBDP) for reinforced concrete frames has been proposed which explicitly considers strength, stiffness, ductility, and structural configuration. The procedure satisfies the design requirements ate two limit states; serviceability limit state (SLS) and ultimate limit state (ULS). To obtain the outer envelop of base shear - roof displacement relationship, a displacement-control non-linear quasi-static analysis has been proposed. The analysis is carried out by imposing a lateral displacement profile on the structure in small increments. The displacement profile is proportional to the first mode shape of the structure, when it is elastic. Under inelastic conditions, the profile is also a function of mode shape of the "yielding" structure at that stage. A computer program has been developed to carry out this quasistatic analysis. The base shear - roof displacement relationship, so obtained is used to assess the suitability of design for stiffness, strength modelled by the ULS. To account for effect of low initial stiffness