Quasi-Static Cyclic Tests of Precast Columns with Steel Section Reinforced UHPC Connection

Abstract

This study investigates the seismic performance of postcast prefabricated concrete columns reinforced with ultrahigh-performance concrete (UHPC) and incorporating internal steel sections at their joints. Through low-cycle reversed loading tests conducted on two prefabricated concrete (PC) columns with UHPC-reinforced steel joints and one RC column cast-in-place, the seismic performance differences between PC and RC are compared. The study examines the influence of varying locations of prefabricated joints on hysteretic behavior, energy dissipation capacity, and deformation capability. The results indicate that the prefabricated columns reinforced with internal steel sections and UHPC connections exhibit higher load-bearing capacity and stiffness, significantly enhancing their seismic performance. Specifically, the PC-2 specimen, with its joint located at the column base, displays excellent initial ductility and energy dissipation but experiences a reduction in load-bearing capacity due to UHPC cracking at the joint in later stages. Conversely, the PC-1 specimen, featuring a joint positioned 450 mm above the bearing platform, exhibits comparable deformation and energy dissipation capabilities to the RC column due to unhindered plastic hinge formation, demonstrating superior seismic performance. The formula for calculating the flexural capacity of I-shaped steel-reinforced concrete sections, based on the internal force equilibrium condition and the lower-bound theorem of plasticity theory, yields a calculation error of less than 10%, confirming its accuracy and providing a scientific basis for relevant design optimizations.