Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Effect of cut-out openings on the axial strength of concrete walls
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.ORCID iD: 0000-0001-9423-7436
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.ORCID iD: 0000-0002-8682-876X
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.ORCID iD: 0000-0003-1329-555X
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.ORCID iD: 0000-0002-5154-7044
Number of Authors: 42016 (English)In: Journal of Structural Engineering, ISSN 0733-9445, E-ISSN 1943-541X, Vol. 142, no 11, article id 4016100Article in journal (Refereed) Published
Abstract [en]

Old structures are frequently modified to comply with current living standards and/or legislation. Such modifications may include the addition of new windows or doors and paths for ventilation and heating systems, all of which require openings to be cut into structural walls. However, effects of the required openings are not sufficiently understood. Thus, the objective of the work reported here was to analyze openings’ effects on the axial strength of large concrete wall panels. Three half-scaled walls with two opening configurations, corresponding to “small” and “large” door openings, were subjected to a uniformly distributed axial load with a small eccentricity. The results indicate that the 25% and 50% reductions in cross-sectional area of the solid wall caused by introducing the small and large openings reduced the load-carrying capacity by nearly 36% and 50%, respectively. The failure progression was captured using digital image correlation technique and the results indicated involvement of a plate mechanism rather than uniaxial behavior as adopted in current design codes. Using a simplified procedure, the load-carrying capacity was predicted using existing design models found in the research literature and design codes.

Place, publisher, year, edition, pages
2016. Vol. 142, no 11, article id 4016100
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-13543DOI: 10.1061/(ASCE)ST.1943-541X.0001558ISI: 000386366600008Scopus ID: 2-s2.0-84991677088Local ID: cc593011-a98a-471f-9ff8-ca86152f99d9OAI: oai:DiVA.org:ltu-13543DiVA, id: diva2:986496
Note

Validerad; 2016; Nivå 2; 2016-11-08 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-09-18Bibliographically approved
In thesis
1. CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory Tests
Open this publication in new window or tab >>CFRP Strengthening of Cut-Out Openings in Concrete Walls – Analysis and Laboratory Tests
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017. p. 159
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Building Technologies
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-61515 (URN)978-91-7583-794-9 (ISBN)978-91-7583-795-6 (ISBN)
Public defence
2017-02-23, F1031, Luleå, 10:00 (English)
Opponent
Supervisors
Note

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

Available from: 2017-01-20 Created: 2017-01-18 Last updated: 2017-11-24Bibliographically approved
2. FRCM-Composites for Strengthening Concrete Walls with Openings: Experimental and Numerical Analysis
Open this publication in new window or tab >>FRCM-Composites for Strengthening Concrete Walls with Openings: Experimental and Numerical Analysis
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Upgrading existing buildings to new functional requirements may require new openings that can weaken the structure, prompting the need for strengthening. In such cases, traditional strengthening solutions, such as creating a reinforced concrete or steel frame around the opening, imply long-term restrictions in the use of the structure.

In this study, the author carries experimental and numerical investigations on fiber reinforced cementitious matrix (FRCM) composites and their effectiveness for strengthening reinforced concrete walls with openings.

To assess the performance of FRCM composite having different fiber types and their suitability for strengthening reinforce concrete walls with openings, single-lap direct shear tests were carried out using carbon, glass, and basalt FRCM-concrete joints. A novel non-contact measurement approach, based on digital image photogrammetry, applied to the experimental study of the bond behavior of FRCM composites was proposed and investigated. The proposed measurement approach showed higher spatial measurement resolution and increased accuracy compared to traditional contact approaches.

The effect of cutout openings on the structural behavior of concrete walls was investigated experimentally, by loading to failure, half-scale, precast reinforced concrete panels with and without openings. The tested specimens were two-way action panels to which axial load with a small eccentricity was applied, thus the tested panels were representative of wall panels in buildings. The effect of cutout openings on the global behavior of a building structure was investigated through finite element analysis of an existing building where cutout openings were introduced in wall panels. Depending on their size, cutout openings can significantly decrease the capacity of the wall. The effectiveness of FRCM strengthening to restore the capacity walls with cutout openings was investigated experimentally. FRCM strengthening increased the capacity of walls having small door type openings (opening width was 25% of the wall’s width) to that of the solid wall. The capacity of the walls with large cutout openings was (opening width was 50% of the wall’s width) was increased to 75% of the solid wall’s capacity. The numerical and experimental analysis indicated that the decrease in axial load caused by cutout openings was proportional to the width opening. However, the numerical analysis of buildings structure indicated that the effects of openings on the buildings load carrying capacity are less severe.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
FRCM, reinforced concrete, walls, openings, strenghtening
National Category
Building Technologies Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-70886 (URN)978-91-7790-205-8 (ISBN)978-91-7790-206-5 (ISBN)
Public defence
2018-11-14, F1031, Luleå University of Technology, Luleå, 09:00 (English)
Opponent
Supervisors
Available from: 2018-09-25 Created: 2018-09-18 Last updated: 2018-11-21Bibliographically approved

Open Access in DiVA

Supplemental data (video)(5409 kB)59 downloads
File information
File name MOVIE01.mp4File size 5409 kBChecksum SHA-512
d93c93b28973dec7010d17891cdc3e2d59ad7979cfa3b38853de3551a5e0da65fab93a320504c27ab50c5bc297a253a8c95303b0759cc929357d2258bffcbbd8
Type movieMimetype video/mp4

Other links

Publisher's full textScopus

Authority records BETA

Popescu, CosminSas, GabrielSabau, CristianBlanksvärd, Thomas

Search in DiVA

By author/editor
Popescu, CosminSas, GabrielSabau, CristianBlanksvärd, Thomas
By organisation
Structural and Construction Engineering
In the same journal
Journal of Structural Engineering
Infrastructure Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 439 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf