Improving the seismic robustness of reinforced concrete frames by using locally hybrid steel-concrete columns

The proposed concept consists in placing a steel profile with limited size inside the reinforced concrete column of the first level of the building. This profile is not considered for the design and is essen-tially assumed to act as a safety belt activated only in case of deficiencies of the concrete under earthquake action, providing thus the requested robustness and limiting the risk of soft-storey mechanisms even in the most unfavorable conditions. Theoretical, experimental and numerical investigations summarized in the pre-sent contribution are aiming at demonstrating the efficiency of the concept.