Axial compression ratio limit for self‐centering precast segmental hollow piers

Abstract

Axial compression ratio limit was investigated for self‐centering precast segmental hollow piers based on post‐earthquake residual axial loading capacity. The analytical method of unbonded posttensioning tendons (PT) stress increment and the simplified method of compression zone height were developed and validated by the finite element model verified by experiments. An analytical formula was deduced to calculate the critical axial compression ratio, which was regarded as the limit and can be obtained when the capacity provided by the noncompression zone at the bottom is equal to the initial axial compression loading. Parameter analysis was conducted to study effects of eight common design parameters on the critical axial compression ratio. The conclusions are summarized that there is good accuracy between the proposed methods for both unbonded PT stress increment and compression zone height and the finite element analysis. The axial compression ratio limit is proposed to be 0.25 when the ratio of energy dissipation (ED) bars is <1.5%. It is an inadvisable solution that more ED bars are matched with higher initial tensioning force of unbonded PT to fulfill the precast segmental piers with good ED capacity and self‐centering capacity in practice.

Parametric experimental investigation of unbonded post‐tensioned reinforced concrete bridge piers under cyclic loading

“…40 However, it is noteworthy that a high initial PT force not only increases the self-centering capacity of the PRC pier but also introduces high compressive stresses at the interface. To overcome this issue, Wang et al 48 proposed an upper limit of the total axial ratio η tol for piers with a ratio of ED bars lower than 1.5%, given by:…”

“…However, it is noteworthy that a high initial PT force not only increases the self‐centering capacity of the PRC pier but also introduces high compressive stresses at the interface. To overcome this issue, Wang et al 48 . proposed an upper limit of the total axial ratio η tol for piers with a ratio of ED bars lower than 1.5%, given by: $$\begin{equation}{\eta _{tol}} = {\eta _G} + {\eta _P} = \frac{{{F_G} + {F_{PT{\_}ini}}}}{{{f_c}{A_g}}} \le 25\% \end{equation}$$where η G and η P are respectively the axial ratios of gravity force and the initial PT force; and f c is the cylinder strength of concrete, which equals to 0.79 cube strength of concrete f cube 12 …”

Precast bridge piers: Construction techniques, structural systems, and seismic response

“…Different types of internal bars have been proposed, one group used steel bars as shown in Figure 3(b) (Chang et al, 2002; Chang et al, 2003; Jia et al, 2020; Ou et al, 2010; Wang et al, 2008). The other group use high strength steel bars (Cai et al, 2018; Ou et al, 2010b; Tong, et al, 2021; Wang et al, 2008; Wang et al, 2017; Zhang, et al, 2021). Others have proposed internal CFRP bars (Cai et al, 2019; Wang et al, 2012) or SMA bars (Akbarnezhad et al, 2022; Li et al, 2017; Nikbakht et al, 2015; Roh and Reinhorn, 2010, Roh et al, 2012, Tazarv and Saiidi, 2015).…”

Energy dissipation and self‐centering capacities of posttensioning precast segmental ultra‐high performance concrete bridge columns

“…The parameters include the aspect ratio, the ED bar ratio, the strength-yield ratio of ED bars, the unbonded length ratio of ED bars, the gravity loading ratio, the initial PT stress, and the PT tendon ratio. 16,[30][31][32] Prototype dimensions of tested specimens are used in the parametric analysis to accurately consider the size effect of bar-slip and the P-Δ effect. The prototype of specimen S-3 is selected to be the reference marked by specimen PS, of which design parameters are shown in Table 3.…”