Comparative seismic performance assessment of RC and RC/ECC hybrid frame structures: a shake table study

This study focuses on the efficient utilization of engineered cementitious composite (ECC) in reinforced concrete (RC) frame structures. In this regard, ECC has been incorporated in the joint panel and plastic hinge zones of the connecting frame elements. For the evaluation of dynamic performance assessment of such hybrid ECC-RC frame structure, a two-story (low rise) RC-frame structure was selected. Two different structural detailing configurations were considered, a model confirming modern seismic code requirements (Code-Compliant Models), while the other was detailed with some seismic code deficiencies (Non-Compliant Models). For experimental testing, 1:3 reduced scale representative models were fabricated. These models were subjected to a 1994 Northridge accelerogram record through a unidirectional shake table. The damage observed in the conventional RC model has exhibited diagonal cracking at the joint panel and concrete crushing. In contrast, ECC-RC models demonstrated minor column damages without severe cracking of the joint core. For dynamic response evaluation, the seismic response parameters (yield stiffness, yield strength, ductility, overstrength factor, and R-factor) for all the models were computed and compared to evaluate the possibility of incorporating ECC at crucial locations. For the ECC enhanced code-compliant and non-compliant models, the response modification factor increased by 37.62% and 16.61%, respectively, compared to the RC countermodels. In addition, the peak input acceleration was correlated with the peak roof displacement to obtain the seismic response envelopes. The performance of ECC-RC models was exceptional for the non-compliant models, which enhance the seismic ductility and energy dissipation for highly optimized frame structures. Hence, it is believed that the efficient use of ECC in critical regions of frame structures can be vital in mitigating the seismic risk.