Strength and ductility of RC beam-column joints of non-safety related structures and recommendations by national standards

Every nuclear facility consists of various structures of varying importance. Standards and design guidelines recommend categorization of these structures based on their importance, safety function that they have to perform, hazard class, etc. In order to economize the designs, the structures that pose only industrial risk are recommended to be designed following the national practice. This paper presents the results of experiments performed on the beam-column joints of such structures to verify their seismic performances. The specimens were full-scale replicas of the joints of the original non safety related structures such as turbine buildings, intake structures and office buildings. The beam-column connections in the original structures either had non-seismic detailing or seismic detailing, but in order to have a comparison, every joint was tested with both types of detailing. The strength and ductility obtained from the experiments for both types was compared with the codal recommended values by different national standards. Conclusions and comments on the suggested values of allowable stresses, assumed ductility values and corresponding strength reduction factors have been made.

Research highlights
► The paper presents results of experiments performed on RC beam-column joints.
► Specimens were replicas of the joints of real life non safety related structures.
► It was found that confinement, in general, improves the seismic behavior of joints.
► Confinement gives only marginal improvement in case of full-scale joints.
► National standards must prescribe limits on joint shear stresses.
► Reduction factors should consider the period of the structure.