Behavior of semi-prefabricated steel-tube double-layer concrete columns under eccentric compression

Abstract

ABSTRACT To promote the application of steel-reinforced-concrete structures in prefabricated concrete structures, the semi-prefabricated steel-tube double-layer concrete (SPSTDC) column was proposed. The eccentric compression mechanical behavior was studied through theoretical analysis, experiments, and numerical simulations. Three possible failure modes, namely, compression failure, total yield failure, and tension failure, were obtained. Then, corresponding calculation methods of the bearing capacity (N u) were established and their effectiveness was verified through comparison with test results. The analysis results showed that N u decreased with the increase in the eccentricity. N u increased with the precast concrete strength, and its effect on N u diminished with increasing eccentricity. The post-cast concrete strength had a smaller effect on N u than the precast concrete strength. N u increased with the increase in the steel ratio α a, while the steel tube strength had little influence on N u. The N–M curve of the SPSTDC column could be divided into three segments, corresponding to the three failure modes. For the compression failure mode, the ultimate load N s decreased with the increase in the ultimate bending moment M s. For the other two failure modes, the pattern was the opposite. The eccentricity had a significant impact on the horizontal lateral deflections of the SPSTDC columns. With the increase in the eccentricity, the horizontal lateral deflection corresponding to N u increased. The horizontal lateral displacement of the mid-height section remained the largest compared with those of other sections. The lateral stiffness increased with the increase in the concrete strength, steel strength, and steel ratio. The impact of the precast concrete strength was the most significant while the influence of the steel tube strength was the weakest.