Research On The Bearing Capacity And Ductility Of The Normal Section Of Reinforced Concrete Z-shaped Cross-section Column

The special-shaped concrete column frame structure has plenty of advantages inarchitectural design, and hereby is widely adopted in civil architecture design.However, as one of the basic sectional forms for special-shaped column components,the Z-shaped cross-section is not fully explicated in existing industrial norms. For thisreason, a self-compiled program and the ANSYS large-scale finite element programare utilized in this paper to fully analyze the normal section bearing capacity andductility of the Z-shaped cross-section column. This research is designed to studymultiple factors’ influence on the bearing capacity and ductility of column section,including material characteristics, sectional dimension, and loading conditions.Detailed tasks include:In the paper, the ANSYS large-scale finite element program is applied to study thecoordination of sectional deformation within elastic range, under the circumstancethat the Z-shaped reinforced concrete cross-section column is bearing eccentricpressure from two directions. According to the theoretical analysis on the Z-shapedcross-section reinforced concrete columns of different sectional dimensions, theZ-shaped cross-section reinforced concrete column is proved to comply with theassumption of plane cross-section, and its positive strain distribution level curve isapproximately a straight line.A self-compiled normal section bearing capacity analysis program is adopted to studythe changes of normal section bearing capacity when the eccentric pressure comesfrom two different directions. It is shown that load angle, axial compression ratio, andreinforcement form have significant influence on normal section’s bearing capacity.The improvement of vertical reinforcement ratio, longitudinal bar strength or concretestrength grade enhances the bearing capacity of normal section to some extent. Inresearches specialized on Z-shaped cross-sections of unequal limb lengths, the mostadverse load angle of cross-section is calculated according to concrete sectionalheight-width ratio and limb height-thickness ratio. Furthermore, it is shown that thedifference between sectional height and width is not suggested to be over large. Onthe other hand, values of sectional bearing capacity may become largely different,giving rise to obviously weak loading angles.Taking advantage of the self-compiled column section curvature ductility computingprogram, the inherent relation between Z-shaped section column curvature ductilityratio and multiple component parameters is analyzed and acquired as well.Furthermore, it is found that, load angle, longitudinal bar configuration, and stirrupconfiguration call have a significant influence on the curvature ductility of theZ-shaped cross-section column. On the contrary, the two parameters of concretestrength and the sectional height-width radio of the Z-shaped cross-section columncreate relatively lower influence on the curvature ductility of cross-section. Accordingto further analysis, configuration of stirrup and longitudinal bar has a certain linkedrelationship, i.e. smaller ratio between stirrup spacing and longitudinal bar diameterleads to higher ductility of the Z-shaped cross-section column.According to the beam-hinge failure mechanism, the relationship between framestructure’s displacement ductility and special-shaped cross-section column’s curvature ductility is further analyzed in this paper. The ratio of curvature ductility forspecial-shaped column under different classes of seismic measure is calculated as well.On this basis, the self-compiled program is applied to nonlinearly analyze theZ-shaped cross-section column under25920kinds of working conditions, as well asto figure out the limit value of axial compression ratio correlated with stirrupcharacteristic value.