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Tests on reinforced concrete slabs with cut-out openings strengthened with fibre-reinforced polymers
Politechnica University of Timisoara.
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion. NORUT, Department of Infrastructure Structures and Materials.ORCID-id: 0000-0002-8682-876X
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.ORCID-id: 0000-0001-9423-7436
2014 (Engelska)Ingår i: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 66, s. 484-493Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper presents the results of experimental investigations on reinforced concrete slabs strengthened using fibre-reinforced polymers (FRP). Eight tests were carried out on four two-way slabs, with and without cut-out openings. Investigations on slabs with cut-outs revealed that the FRP can be placed only around the edges of the cut-out when retrofitting the slabs whereas, in the situation of inserting cut-outs combined with increased demands of capacity, it is necessary to apply FRP components on most of the soffit of the slab. The proposed strengthening system enabled the load and deflection capacities of the FRP-strengthened slabs, in relation to their un-strengthened reference slabs, to be enhanced by up to 121% and 57% for slabs with and without cut-outs respectively.

Ort, förlag, år, upplaga, sidor
2014. Vol. 66, s. 484-493
Nyckelord [en]
Civil engineering and architecture - Building engineering
Nyckelord [sv]
Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
Nationell ämneskategori
Infrastrukturteknik
Forskningsämne
Konstruktionsteknik
Identifikatorer
URN: urn:nbn:se:ltu:diva-10489DOI: 10.1016/j.compositesb.2014.06.008ISI: 000342247500049Scopus ID: 2-s2.0-84904298913Lokalt ID: 94dd8eba-eb71-4369-b4dd-cbfc03582655OAI: oai:DiVA.org:ltu-10489DiVA, id: diva2:983434
Anmärkning
Validerad; 2014; 20140616 (cospop)Tillgänglig från: 2016-09-29 Skapad: 2016-09-29 Senast uppdaterad: 2018-07-10Bibliografiskt granskad
Ingår i avhandling
1. CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory Tests
Öppna denna publikation i ny flik eller fönster >>CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory Tests
2017 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Redesigning buildings to improve their space efficiency and allow changes in use is often essential during their service lives to comply with shifts in living standards and functional demands.This may require the introduction of new openings in elements such as beams, walls, and slabs,which inevitably reduces their structural performance and hence requires repair or strengthening.However, there are uncertainties regarding both the effects of openings and the best remedial optionsfor them. Traditionally, two methods have been used to strengthen reinforced concrete (RC) walls with openings, these being either to create a frame around the opening using RC/steel membersor to increase the cross-sectional thickness. Currently, intervention in existing buildings must be minimal in order to minimise inconvenience caused by limiting the use of the structure during repairs. One option is to use externally-bonded fibre-reinforced polymers (FRPs).

In this study, the author reports on an experimental investigation of the effectiveness of carbonFRP (CFRP)–based strengthening for restoring the axial capacity of a solid reinforced concretewall after cutting openings. Nine half-scale specimens, designed to represent typical wall panels in residential buildings with and without door-type openings, were tested to failure. The walls were tested in two-way action and subjected to axial loading with low eccentricity (defined as one sixth of the wall’s thickness) along the weak axis to represent imperfections due to thickness variation and misalignment of the panels during the construction process. An extensive instrumentation scheme was used to monitor the specimen’s behaviour during the loading cycles. In addition to classical approaches for measuring strains and displacements, optical 3D measurements were also acquired using the digital image correlation (DIC) technique. These provided better overviews of the failure mechanism by recording the crack pattern development and deformation of the walls throughout the loading history.

Reducing the cross-sectional area by cutting out openings i.e. 25% (hereafter referred to as small opening) and 50% (hereafter referred to as large opening) led to 36% and 50% reductions in peak loads, respectively. In both situations the failure was brittle due to crushing of concrete with spalling and reinforcement buckling. The CFRP strengthening increased the axial capacity of walls with small and large openings by 34 – 50% and 13 – 27%, respectively. This partially restored theircapacities to 85 – 95% and 57 – 63% of their precutting capacity (i.e. solid wall), respectively. A procedure based on a rigid-plastic approach for evaluating the ultimate load of walls with cut-out openings that have been strengthened with FRPs was also proposed in this study. Predictions made using the proposed method agree closely with experimental results.

Ort, förlag, år, upplaga, sidor
Luleå: Luleå University of Technology, 2017. s. 159
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Nationell ämneskategori
Husbyggnad
Forskningsämne
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-61515 (URN)978-91-7583-794-9 (ISBN)978-91-7583-795-6 (ISBN)
Disputation
2017-02-23, F1031, Luleå, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

Examining Committee: Professor Karin Lundgren, Division of Structural Engineering, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden

Professor Henrik Stang, Section for Structural Engineering, Department of Civil Engineering, Technical University of Denmark, Lyngby, Denmark

Professor Mats Oldenburg, Division of Mechanics of Solid Materials, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden

Tillgänglig från: 2017-01-20 Skapad: 2017-01-18 Senast uppdaterad: 2017-11-24Bibliografiskt granskad

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