Monolithic equivalent stiffness of precast columns with grouted splice sleeve connections

Marcelo De Araujo Ferreira,Bruna Catoia,Luís Augusto Bachega

doi:10.1590/s1983-41952021000100015

Marcelo De Araujo Ferreira, Bruna Catoia + Show 1 more

Open Access

https://doi.org/10.1590/s1983-41952021000100015

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Abstract

abstract The aim of this paper is the validation of monolithic equivalent stiffness applied to precast columns with grouted splice sleeve connections, wherein spliced precast elements have been compared with continuous monolithic elements. The experimental investigation has been carried out with bending tests for two spliced elements (L1 and L2), comparing the deflections along these elements with the results obtained from two monolithic elements (M1 and M2). The grouted splice sleeve connections have been characterized by their rotational stiffness (moment-rotation relationship), ultimate strength, and ductility, allowing the calibration of the equation for the secant stiffness according to ABNT NBR9062:2017. Based on the experimental results, the effective deformation length within the connection zone obtained was Led = 20ϕ, corresponding to a secant stiffness of Rsec = 77,785 kN∙m/rad. Although relative rotations have been observed at the grouted splice joint, the deflections along the precast spliced elements were very close to the deflections along the monolithic elements. A strong convergence for all phases of the load x displacement curves has been observed, as well as good approximation in terms of rotational stiffness, strength and ductility. Therefore, based on the analysis of the experimental results, the requirement to define the monolithic equivalent stiffness for the precast columns has been met.

Highlights

In addition to the influence of the semirigid behavior of beam-column connections, lateral sway in precast structures is highly affected by the actual stiffness of the precast columns, which is affected by premature cracking during the transitory phases of production and during the assembly of structural precast members, as well as affected by crack formation within the serviceability limit state.Column connections can be positioned either at the bottom or at mid-height of the column, which is the case in multistory buildings
7 CONCLUSIONS Based on the analysis and interpretation of the experimental results, it has been evidenced that the precast members with grouted splice sleeve connections presented relative stiffness that was equivalent to the monolithic members
The higher concentration of stirrups surrounding the splice sleeves within the connection zone, with the addition of longitudinal reinforcement in the segmented models promoted higher confinement for the longitudinal reinforcements and, better crack control within the connection zone when comparing with the monolithic elements

Summary

Introduction

In addition to the influence of the semirigid behavior of beam-column connections, lateral sway in precast structures is highly affected by the actual stiffness of the precast columns, which is affected by premature cracking during the transitory phases of production and during the assembly of structural precast members, as well as affected by crack formation within the serviceability limit state.Column connections can be positioned either at the bottom or at mid-height of the column, which is the case in multistory buildings. For precast columns consisting of spliced members, the actual lateral stiffness of the whole column can be affected by relative displacements within the joints, either at the mid-height column-to-column joint or at the bottom of column-to-foundation joints. As such, these localized deformations in the joints will increase the lateral sway of the building, especially in industrial buildings with cantilevered columns. For multistory buildings, with joints at mid-height of the columns, the structural continuity of precast columns is highly dependent on the connection behavior itself

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