Theoretical approaches for modelling buckling effects in rebars of RC members

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Abstract

Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stressâstrain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrupsâ pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrupsâ failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the critical conditions in longitudinal bars. A discrete mechanical model is proposed, based on the solution of a continuous beam with elastic supports, with deflections restrained in one side to simulate the presence of the concrete core. It allows describing the transition from local buckling (between the stirrups) and global buckling, on the basis of the relative stiffness stirrup-bar. Two other methods corresponding to different computational efforts are also adopted for the sake of comparison. In particular, non-linear finite element analyses are carried out including the effect of strain hardening in the constitutive law of steel and finally, comparisons are made with a simplified closed-form solution proposed in the literature. This last comparison allows to assess the reliability of these expressions and their applications for obtaining parametric considerations useful for design.
Lingua originaleEnglish
pagine (da-a)5309-5327
Numero di pagine19
RivistaBulletin of Earthquake Engineering
Volume15
Stato di pubblicazionePublished - 2017

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buckling
reinforced concrete
Buckling
Reinforced concrete
modeling
deflection
steel
steels
Concretes
concrete structures
Steel
concrete structure
strain hardening
ductility
hardening
Strain hardening
Concrete construction
confining
Ductility
stiffness

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Building and Construction
  • Geotechnical Engineering and Engineering Geology
  • Geophysics

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title = "Theoretical approaches for modelling buckling effects in rebars of RC members",
abstract = "Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stress{\^a}strain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrups{\^a} pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrups{\^a} failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the critical conditions in longitudinal bars. A discrete mechanical model is proposed, based on the solution of a continuous beam with elastic supports, with deflections restrained in one side to simulate the presence of the concrete core. It allows describing the transition from local buckling (between the stirrups) and global buckling, on the basis of the relative stiffness stirrup-bar. Two other methods corresponding to different computational efforts are also adopted for the sake of comparison. In particular, non-linear finite element analyses are carried out including the effect of strain hardening in the constitutive law of steel and finally, comparisons are made with a simplified closed-form solution proposed in the literature. This last comparison allows to assess the reliability of these expressions and their applications for obtaining parametric considerations useful for design.",
author = "Giovanni Minafo' and Maurizio Papia",
year = "2017",
language = "English",
volume = "15",
pages = "5309--5327",
journal = "Bulletin of Earthquake Engineering",
issn = "1570-761X",
publisher = "Springer Netherlands",

}

TY - JOUR

T1 - Theoretical approaches for modelling buckling effects in rebars of RC members

AU - Minafo', Giovanni

AU - Papia, Maurizio

PY - 2017

Y1 - 2017

N2 - Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stressâstrain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrupsâ pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrupsâ failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the critical conditions in longitudinal bars. A discrete mechanical model is proposed, based on the solution of a continuous beam with elastic supports, with deflections restrained in one side to simulate the presence of the concrete core. It allows describing the transition from local buckling (between the stirrups) and global buckling, on the basis of the relative stiffness stirrup-bar. Two other methods corresponding to different computational efforts are also adopted for the sake of comparison. In particular, non-linear finite element analyses are carried out including the effect of strain hardening in the constitutive law of steel and finally, comparisons are made with a simplified closed-form solution proposed in the literature. This last comparison allows to assess the reliability of these expressions and their applications for obtaining parametric considerations useful for design.

AB - Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stressâstrain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrupsâ pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrupsâ failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the critical conditions in longitudinal bars. A discrete mechanical model is proposed, based on the solution of a continuous beam with elastic supports, with deflections restrained in one side to simulate the presence of the concrete core. It allows describing the transition from local buckling (between the stirrups) and global buckling, on the basis of the relative stiffness stirrup-bar. Two other methods corresponding to different computational efforts are also adopted for the sake of comparison. In particular, non-linear finite element analyses are carried out including the effect of strain hardening in the constitutive law of steel and finally, comparisons are made with a simplified closed-form solution proposed in the literature. This last comparison allows to assess the reliability of these expressions and their applications for obtaining parametric considerations useful for design.

UR - http://hdl.handle.net/10447/243877

UR - https://link.springer.com/article/10.1007/s10518-017-0184-9

M3 - Article

VL - 15

SP - 5309

EP - 5327

JO - Bulletin of Earthquake Engineering

JF - Bulletin of Earthquake Engineering

SN - 1570-761X

ER -