Structural repair/strengthening of RC columns

Frangou, Michael; Pilakoutas, Kypros; Dritsos, Stephanos E.

doi:10.1016/0950-0618(95)00013-6

Cited by 95 publications

(36 citation statements)

References 1 publication

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“…The amount and layout of metal straps is based on the principle that metal straps are treated as conventional tensile reinforcement, and can be designed according to the procedure outlined in Garcia et al (2014a). The straps were post-tensioned to approximately 30-40% of their yield strength based on previous experience from tests on columns (Frangou et al 1995;Moghaddam et al 2010), and on substandard full-scale joint subassemblies retrofitted with PTMS (Helal 2012). To ensure such post-tensioning force, the tensioning tool was pre-calibrated by applying different levels of air pressure, while monitoring the effective strap force after fastening the push type seals, using a double pulley setup mounted on a universal testing machine.…”

Section: Post-tensioned Metal Strappingmentioning

confidence: 99%

“…Previous research by Frangou et al (1995) and Frangou (1996) led to the development of a novel technique for retrofitting RC beams and columns using Post-Tensioned Metal Straps (PTMS). The technique uses ductile high-strength steel straps post-tensioned around RC elements using pneumatic strapping tools as those used in the packaging industry (see Fig.…”

Section: Introductionmentioning

confidence: 99%

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Seismic retrofitting of RC buildings using CFRP and post-tensioned metal straps: shake table tests

Garcia

Pilakoutas

Hajirasouliha

et al. 2015

Bull Earthquake Eng

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This article examines the effectiveness of two innovative retrofitting solutions at enhancing the seismic behaviour of a substandard reinforced concrete building tested on a shake table as part of the Pan-European funded project BANDIT.To simulate typical substandard construction, the reinforcement of columns and beam-column joints of the full-scale structure had inadequate detailing. An initial series of shake table tests were carried out to assess the seismic behaviour of the bare building and the effectiveness of a first retrofitting intervention using Post-Tensioned Metal Straps. After these tests, columns and joints were repaired and subsequently retrofitted using a retrofitting solution consisting of Carbon Fibre Reinforced Polymers and Post-Tensioned Metal Straps applied on opposite frames of the building. The building was then subjected to unidirectional and three-dimensional incremental seismic excitations to assess the effectiveness of the two retrofitting solutions at improving the global and local building performance. The article provides details of the above shake table testing programme and retrofitting solutions, and discusses the test results in terms of the observed damage, global damage indexes, performance levels and local strains. It is shown that whilst the original bare building was significantly damaged at a peak ground acceleration (PGA) of 0.15g, the retrofitted building resisted severe three-dimensional shake table tests up to PGA=0.60g without failure. Moreover, the retrofitting intervention enhanced the interstorey drift ratio capacity of the 1 st and 2 nd floors by 160% and 110%, respectively. Therefore, the proposed dual retrofitting system is proven to be very effective for improving the seismic performance of substandard buildings.

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Section: Post-tensioned Metal Strappingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seismic retrofitting of RC buildings using CFRP and post-tensioned metal straps: shake table tests

Garcia

Pilakoutas

Hajirasouliha

et al. 2015

Bull Earthquake Eng

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“…Experimental investigations on damaged RC columns showed that the axial compressive strength and ductility was greatly improved by strengthening using steel cage and steel encasement approach [12]. However, considerable improvement in shear strength with stable hysteretic loops at higher ductility levels was only achieved when the columns were retrofitted over the entire length using steel jackets [13].…”

Section: Introductionmentioning

confidence: 99%

Seismic strengthening of RC columns using external steel cage

Nagaprasad

Sahoo

Durgesh

2009

Earthq Engng Struct Dyn

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SUMMARYSteel caging technique is commonly used for the seismic strengthening of reinforced concrete (RC) columns of rectangular cross-section. The steel cage consists of angle sections placed at corners and held together by battens at intervals along the height. In the present study, a rational design method is developed to proportion the steel cage considering its confinement effect on the column concrete. An experimental study was carried out to verify the effectiveness of the proposed design method and detailing of steel cage battens within potential plastic hinge regions. One ordinary RC column and two strengthened columns were investigated experimentally under constant axial compressive load and gradually increasing reversed cyclic lateral displacements. Both strengthened columns showed excellent behavior in terms of flexural strength, lateral stiffness, energy dissipation and ductility due to the external confinement of the column concrete. The proposed model for confinement effect due to steel cage reasonably predicted moment capacities of the strengthened sections, which matched with the observed experimental values.

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“…Many investigations 2,3 showed that the bonded-type strengthening procedures are effective in enhancing the strength and ductility of existing reinforced concrete columns. However, few drawbacks were also identified 4,5 such as, debonding of external laminates from concrete surface, high cost, and poor long-term behavior of the system owing to different coefficients of thermal expansion of concrete, adhesive, and non-metallic fiber laminates.…”

Section: Introductionmentioning

confidence: 99%

Axial behaviour of reinforced concrete short columns strengthened with wire rope and T-shaped steel plate units

Yang¹,

Ashour²,

Lee³

2009

Magazine of Concrete Research

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This paper presents a relatively simple column strengthening procedure using unbonded wire rope and T-shaped steel plate units. Twelve strengthened columns and an unstrengthened control column were tested to failure under concentric axial load to explore the significance and shortcomings of the proposed strengthening technique. The main variables investigated were the volume ratio of wire ropes as well as geometrical size and configuration of T-shaped steel plates. Axial load capacity and ductility ratio of columns tested were compared with predictions obtained from the equation specified in ACI 318-05 and models developed for conventionally tied columns, respectively. The measured axial load capacities of all strengthened columns were higher than predictions obtained from ACI 318-05, indicating that the ratio of the measured and predicted values increased with the increase of volume ratio of wire ropes and flange width of T-shaped steel plates. In addition, at the same lateral reinforcement index, a much higher ductility ratio was exhibited by strengthened columns having a volume ratio of wire ropes above 0·0039 than tied columns. The ductility ratio of strengthened columns tested increased with the increase of flange width, thickness, and web height of T-shaped steel plates. A mathematical model for the prediction of stress–strain characteristics of confined concrete using the proposed strengthening technique is developed, that was in good agreement with test results.

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Structural repair/strengthening of RC columns

Cited by 95 publications

References 1 publication

Seismic retrofitting of RC buildings using CFRP and post-tensioned metal straps: shake table tests

Seismic retrofitting of RC buildings using CFRP and post-tensioned metal straps: shake table tests

Seismic strengthening of RC columns using external steel cage

Axial behaviour of reinforced concrete short columns strengthened with wire rope and T-shaped steel plate units

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