NTC-compatible and performance-based seismic assessment using Cloud Analysis: application to an RC frame

Italian code provides the option for non-linear time-history analysis for the multi-degree-of-freedom (MDOF) structures (NTC). A non-linear time-history analysis procedure known as “Cloud Analysis” employs the struc- tural response to a suite of un-scaled ground motion records. Cloud Analysis results can be directly implemented in es- tablished procedures for performance-based safety-checking of existing buildings. It can be shown that the Cloud Anal- ysis lends itself quite well also to NTC-based safety-checking with non-linear dynamic analysis. A closed-form factor can quantify the ratio between performance-based and NTC-based safety-checking global demand to capacity ratios for the structure. The procedure is demonstrated for a nonlinear model with distributed plasticity of a frame belonging to an existing RC school structure modelled considering the flexural-shear-axial interactions.