The effect of preloading on the strength of jacketed R/C columns

Papanikolaou, Vassilis K.; Paraskevopoulos, Elias; Kappos, Andreas J.

doi:10.1016/j.conbuildmat.2012.07.100

Cited by 9 publications

(5 citation statements)

References 9 publications

(12 reference statements)

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“…It is a popular seismic retrofit method that has been actively researched and applied in the past (e.g. [1][2][3]) and attracts also more recent scientific interest, with researchers investigating it experimentally [4][5][6][7][8][9], analytically [10][11][12] or with the use of structural analysis software [10,[13][14][15]. The focus of recent research efforts appears to be on the better modelling of the interface between the existing element and the concrete jacket, the improvement of analytical methods and the use of new materials.…”

Section: Introductionmentioning

confidence: 99%

Optimized seismic retrofit of steel-concrete composite buildings

Papavasileiou

Charmpis

Lagaros

2020

Engineering Structures

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This work is focused on comparatively assessing the cost-effectiveness of three seismic retrofit approaches for non-code-conforming frame buildings with steel-concrete composite columns.The first two of the assessed retrofit approaches aim in indirectly enhancing structural system performance by strengthening individual composite columns using reinforced concrete jackets or concrete-covered steel cages. The third retrofit approach considered aims in upgrading the composite building frame at hand by installing steel bracings at selected bays. A specially developed structural optimization procedure is used to perform an objective comparison of the cost-effectiveness of the three retrofit approaches. The objective of the optimization procedure is to minimize the total retrofit material cost, while constraints are imposed to ensure the satisfaction of design requirements for the retrofitted structure regarding member capacities (according to Eurocodes 3 and 4 for steel beams and composite columns, respectively), structural system performance under horizontal loading (based on interstorey drifts calculated by pushover analyses) and fundamental periods (obtained from eigenvalue analyses). By defining 30 cases of under-designed 2-storey, 4-storey and 6-storey composite buildings (i.e. buildings with steel-concrete composite columns), an extensive numerical investigation involving 120 retrofit optimization runs was conducted. The results obtained provide insight into the relative cost-effectiveness of the three seismic retrofit approaches and reveal certain conditions under which each approach is economically most viable.

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Section: Introductionmentioning

confidence: 99%

Optimized seismic retrofit of steel-concrete composite buildings

Papavasileiou

Charmpis

Lagaros

2020

Engineering Structures

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“…The concrete grades selected for the jacket were C20/25, C25/30, C30/37 and C50/60, whereas B500C (characteristic yield strength f yk = 500 MPa) ribbed bars were used for the longitudinal and transverse reinforcement. Another parameter of investigation was the dimensionless axial load, ν = N/(b c h c f c,c + (b J h J − b c h c )•f c,J ), which was considered to be applied only to the core cross-section [19] and ranged between 0 and 40%. All the groups defined for the needs of the parametric study are shown in Table A1 of Appendix B.…”

Section: Monolithicity Factors Derived From Numerical Studiesmentioning

confidence: 99%

Background to the Monolithicity Factors for the Assessment of Jacketed Reinforced Concrete Columns

Thermou

Kappos

2022

Buildings

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The paper presents the background to the expressions adopted in the new Eurocode 8—3 for jacketed reinforced concrete columns. These are based on the commonly adopted concept of monolithicity factors (ratios of resistance of the jacketed section to that of an identical monolithic one). These factors are derived here in two ways: (i) by fitting experimental results for jacketed columns and (ii) by an extended parametric study of substandard reinforced concrete (R/C) members that were retrofitted by adding R/C jackets, analysed using a model developed by the authors that takes into account slip at the interface. Apart from the cross-section geometry and the thickness of the jacket, parameters of the investigation were the material properties of the core cross-section and the jacket, as well as the percentage of longitudinal reinforcement of the jacket and the percentage of dowels placed to connect the existing member to the jacket. It was found that the parameter that had the most visible effect on these factors was the normalised axial load (ν). The finally adopted factors are either simple functions of ν or constant values.

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“…Beushausen et al, 2012; Jin et al, 2017; Kim et al, 2002a, 2002b), and some on the effects of preload on concrete-filled composite members (e.g. Li et al, 2019; Liew and Xiong, 2009, 2012; Papanikolaou et al, 2013; Patel et al, 2013, 2014), but only few considered early age and sustained loads. Some of the existing models are discussed in section 2 of this paper.…”

Section: Introductionmentioning

confidence: 99%

Development of strength and elastic modulus of concrete sealed in steel tube under sustained load at early age

Jiao

Han

Xie

et al. 2020

Advances in Structural Engineering

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Concrete-Filled Steel Tubular Structures (CFSTSs) have become popular among the structural engineering community due to significantly higher load carrying capacity compared to conventional reinforced-concrete structures. Much research has been conducted on understanding the behavior of CFSTSs under various loading conditions and design theories have been established to predict the load carrying capacities of such structures. However, existing models do not consider the effects of sustained early loads on concrete strength and elastic modulus development of CFSTSs. With the need for rapid construction, CFSTSs may be subjected to loading at an early stage before concrete is fully cured. Such early loading may incur negative effects on strength and elastic modulus development of concrete within the confined environment. This paper propose theoretical models based on the compressive packing model (CPM) to simulate strength and elastic modulus development of early-age concrete under sustained stress. Development of concrete properties at early age is described using Hydration kinetics, and maximum paste thickness in the CPM model is modified using energy conservation to simulate sustained loads. Early concrete strength and the elastic modulus development rules were investigated experimentally for sustained loads. Predictions from the proposed models are compared with conventional models from CEB-FIP Model Code. Results showed that when loaded at a very early stage, a relatively high stress to strength ratio will result in causing damage in concrete. Such damage significantly affects the strength and elastic modulus development. Compared with concrete loaded at 28 days, concrete loaded at early stages showed significant reduction in concrete strength and elastic modulus.

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The effect of preloading on the strength of jacketed R/C columns

Cited by 9 publications

References 9 publications

Optimized seismic retrofit of steel-concrete composite buildings

Optimized seismic retrofit of steel-concrete composite buildings

Background to the Monolithicity Factors for the Assessment of Jacketed Reinforced Concrete Columns

Development of strength and elastic modulus of concrete sealed in steel tube under sustained load at early age

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