A Novel UHPC-NC Composite Column Frame Structure: Design and Seismic Performance Investigation

Existing studies have demonstrated that insufficient horizontal deformation capacity of columns under high axial compression ratios constitutes a key factor leading to seismic damage in ordinary concrete frame structures. This paper proposes a novel framed structure incorporating composite columns by combining ultra-high performance concrete (UHPC), which exhibits excellent mechanical properties, with normal concrete (NC). The design concept maintains the overall mechanical performance of the composite column frame structure while significantly reducing the lateral stiffness when the composite columns are configured in a “split-column form.” For instance, the lateral stiffness of ZH-5 in the “split-column form” is only one-tenth of that of ZT-1 in its initial state, leading to a substantial enhancement in horizontal deformation capacity. This design approach maintains the overall mechanical performance of the composite column frame structure while significantly enhancing its horizontal deformation capacity by reducing lateral stiffness through the “split-column” configuration. Using the ABAQUS finite element software 2021, a finite element model of a multi-story frame column structure was developed. Research findings indicate that the frame structure utilizing UHPC-NC composite columns exhibits reduced tensile damage, lower peak and plastic displacements, and a relatively smaller inter-story drift angle. Specifically, the plastic drift angle of the UHPC-NC composite column frame structure from the first to the fourth story is 5% to 31% smaller than that of the conventional reinforced concrete column frame structure. The novel UHPC-NC composite column frame structure demonstrates superior seismic performance.