| 1. |
- Elfgren, Lennart, 1942-, et al.
(författare)
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Assessment of Fasteners to Concrete : A Tribute to Rolf Eligehausen
- 2017
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Ingår i: Connections between Steel and Concrete. - Stuttgart. - 9783945773062 ; , s. 1294-1302
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Konferensbidrag (refereegranskat)abstract
- Some examples are given of assessment of fastenings to concrete structures and the work started by Rolf Eligehausen in fib Task Group 2.9 “Fastenings to structural concrete and masonry”. Studies have been made on e.g. the influence of creep on adhesive anchors and of surface reinforcement and size effects on headed anchors.
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| 2. |
- Lindblad, Sverker, 1946, et al.
(författare)
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Delade uppfattningar i den svenska opinionen: Internationella jämförelser av skolresultat och bedömningar av skolans kvalitet
- 2015
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Ingår i: Annika Bergström, Bengt Johansson, Henrik Oscarsson och Maria Oskarson (Red): Fragment. Göteborg: SOM-institutet. - Göteborg : University of Gothenburg. - 9789189673328 ; , s. 149-162
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Vi har i den här undersökningen visat att svenska folket i stort ställer sig kritiska till utvecklingen av svenska skolans kvalitet under senare år. Vid bedömningen av skolans kvalitet och de internationella jämförelsernas betydelse är skillnaderna mellan de olika partiernas sympatisörer förhållandevis små. Väljarrollen är av begränsad betydelse i båda avseendena och detsamma gäller rollen som anställd, då lärarna som direkt berörda i huvudsak gör samma bedömningar som svenska folket. Brukarna – eleverna - är dock något mindre kritiska till utvecklingen av kvaliteten i den svenska skolan. Ser vi då hur medborgarna ställer sig till de internationella jämförelserna av skolresultat som användbara mått på skolans kvalitet får vi en intressant men lite komplicerad resultatbild. För det första kan vi se att dessa undersökningar – då framför allt OECDs PISA-undersökningar – väckt stor uppmärksamhet i massmedia och då också används som argument bland politiker för att hävda att det går utför med svensk skola med hänvisning till att svenska elever presterar allt sämre i dessa underökningar. För det andra kan vi se att en ganska stor del av opinionen (drygt 40 procent) menar dessa internationella jämförelser är användbara för att bedöma skolans kvalitet, medan en fjärdedel menar att de inte är användbara och en tredjedel är osäkra. Det visar sig vid närmare analyser att den skolkritiska opinionen har tydligt delade uppfattningar om användbarheten hos dessa jämförelser. Det innebär – som vi ser det – att medborgarna använder sig av olika referenspunkter i sina bedömningar av skolans kvalitet och att de resultat av internationella mätningar som presenteras i massmedia har olika genomslag i befolkningen – vilket också återspeglas i att de har skilda betydelser inom olika sociala kategorier. Den fråga som vi ställer oss här är vilken betydelse som den här utvecklingen har för det utbildningspolitiska landskapet. Vi menar att tre punkter behöver analyseras närmare: För det första, hur fungerar de postpolitiska instrumenten i det politiska landskapet. Hur pass neutrala eller tendensiella är bruket av instrumenten som underlag för politiska diskussioner och beslut? Vi menar att våra undersökningar pekar i riktning mot att de har olika innebörder för olika delar av befolkningen – t.ex. i termer av användbarhet. För det andra, hur används dessa instrument? Vi menar här att det är viktigt att skilja mellan de olika undersökningarna och deras resultat och hur de utnyttjas. Exempelvis är det bara vissa delar av PISA-undersökningarna som används – då med förtecken av internationell konkurrens och effektivitet – medan merparten av publikationer som bygger på empiriska internationella jämförelser handlar om bildningsklyftor och frågor om brister i jämlikhet i utbildning (se Lindblad mfl. 2015). Och för det tredje – vad är det för syn på och behov av bildning och utbildning som presenteras? Efter vad vi ser är det ett särskilt sätt att se på utbildning som betonas enligt punkterna ovan. Detta innebär att viktiga utbildningsfrågor försummas – som att bilda medborgarna till kulturellt kompetenta personer i ett flerkulturellt samhälle.
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| 3. |
- Lindblad, Sverker, 1946, et al.
(författare)
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The Public Opinion in Sweden on Educational Restructuring and Governing by International Large-Scale Assessments : Paper presented at the Roundtable Session "Education reform and privatization in diverse contexts" at the Comparative and International Education Society 2019 meeting in San Francisco, USA
- 2019
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Ingår i: Proceedings from the Comparative and International Education Society 2019 meeting in San Francisco, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study is based on an interest in the interplay between science and society, conceptualized as an agora with different positions and actors (Nowotny et al, 2001) in contextualizing and relevancing research. Our case is Sweden as a Nordic Welfare state, transforming a centralized, state-driven reformistic welfare state education system into a highly restructured system in terms of privatization, decentralization and deregulation, including school choice based on vouchers. International large scale assessments (ILSA) such as the OECD PISA studies and the IEA TIMSS program are vital in current public discourses on education, and supranational organizations such as the OECD are asked by the government advice how to deal with the problems and gaps indicated by PISA results (Lindblad, Pettersson & Popkewitz, 2018). We focus on the public opinion as part of the education agora problematic. We ask what are the views considering different aspects of school restructuring and about the uses of ILSA in governing and standardizing school? Are there groups with contradictory views and what are their locations in the social and political demography of the opinion? Data for our analyses were collected and organized by the SOM-institute at the university if Gothenburg in their annual national polls in Sweden. We put forward a set of questions on education quality and governance in the polls. A response ratio of 55 percent (n=1700 individuals) was obtained from a national sample of respondents at the end of 2017. These data are combined with data from previous studies at the SOM-institute. Considering views on schooling the trust in as an institution and in teachers is rather stable and rather high over the years, but a common view is that the quality of the school is getting worse. Considering different aspects of educational restructuring the public opinion is mostly taking a negative stance – no more privatization or profits in school business, and more of state governing. To analyze the demography of the public opinion we identified four distinct clusters: (A) supporters of reformistic welfare state schooling (34 percent), (B) disappointed supporters of welfare state schooling (15 percent), (C) uninformed opponents of welfare state schooling (n=30 percent), and (D) radical opponents of reformist welfare state schooling who instead strives for further restructuring (21 percent). Thus, the public opinion is disjointed and polarized in their views on schooling, which in turn corresponds to positions in the social structure and political preferences, where e.g. clusters C and D are to a large extent including conservatives and right-wing populists, while clusters A and B include more of social democrats and the green party. ILSA is regarded as significantly more useful for governing schooling in cluster C and most of all in cluster D. This study increase our understanding of the current education agora with a disjointed and somewhat polarized public opinon, where governing by ILSA in the current welfare state context is a position presently occupied by restructuring proponents and the political right, with its emphasis on school results, efficiency and schooling for international competition.
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| 4. |
- Lindblad, Sverker, 1946, et al.
(författare)
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The Public Opinion on Educational Qualities in Postpolitical Times: International Comparisons in Welfare State Governance
- 2016
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Ingår i: American Educational Research Association Conference Online Program 2016. - 0163-9676.
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Konferensbidrag (refereegranskat)abstract
- The case is a Nordic welfare state where governing by means of international comparisons (IC) is very important. Which educational qualities are emphasized in this “post-political” way of governing? We analyzed conceptions among citizens – to what extent is the opinion accepting governing by means of IC. We turned to a national sample of citizens (n= 1636 respondents). The opinion was divided. A large share trusted in IC and another large share did not accept their relevance. This split was related to differences in terms of gender, social position and educational level. Thus, there is no general acceptance of IC and their relevance. IC is problematic to treat as a quick fix to determine educational ambitions or strategies for educational improvement.
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| 5. |
- Nilforoush, Rasoul, et al.
(författare)
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Experimental Evaluation of Influence of Member Thickness, Anchor-Head Size, and Orthogonal Surface Reinforcement on the Tensile Capacity of Headed Anchors in Uncracked Concrete
- 2018
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Ingår i: Journal of Structural Engineering. - : American Society of Civil Engineers (ASCE). - 0733-9445 .- 1943-541X. ; 144:4
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Tidskriftsartikel (refereegranskat)abstract
- Cast-in-place headed anchors with different head sizes embedded in plain and reinforced concrete members of various thicknesses were subjected to pullout tests. The influence of member thickness, size of the anchor head, and orthogonal surface reinforcement on the tensile capacity and performance of anchor bolts was evaluated. The member thickness varied from 1.5 to 3.0 times the anchor embedment depth and headed anchors with small, medium, and large heads were tested.The experimental results of the present study showed that increasing member thickness and/or the use of orthogonal surface reinforcement lead to increased anchorage capacity and anchorage ductility, whereas the anchorage stiffness decreases slightly. In contrast to the anchorage ductility, the tensile breakout resistance and the anchorage stiffness increase significantly with increasing size of the anchor head.The experimental results corresponded closely to numerical results from a previous study (Nilforoush et al. 2016 a & b), which suggested a modified model incorporating several modification factors for improving the predictive capability of the Concrete Capacity (CC) method. In the present study, these factors yielded improved prediction of the tensile breakout capacity of the tested headed anchors.
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| 6. |
- Nilforoush, Rasoul, et al.
(författare)
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Experimental evaluation of tensile behaviour of single cast-in-place anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete
- 2017
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 147, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- Cast-in-place anchor bolts embedded in plain and steel fibre-reinforced normal- and high-strength concrete members were subjected to monotonic tensile loads. The influence of the concrete member thickness, concrete strength, and the addition of steel fibres to the concrete mixture, on the anchorage capacity and performance was evaluated. The experimental results were evaluated in terms of anchorage capacity, anchorage ductility and stiffness as well as failure mode and geometry. Furthermore, the validity of Concrete Capacity (CC) method for predicting the tensile breakout capacity of anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete members was evaluated.The anchorage capacity and ductility increased slightly with increasing member thickness, whereas the anchorage stiffness decreased slightly. In contrast to the anchorage ductility, the anchorage capacity and stiffness increased considerably with increasing concrete compressive strength. The anchorage capacity and ductility also increased significantly with the addition of steel fibres to the concrete mixtures. This enhanced capacity and ductility resulted from the improved flexural tensile strength and post-peak cracking behavior of steel fibre-reinforced concrete.The average ratio of measured strengths to those predicted by the CC method for anchors in plain concrete members was increased from 1.0 to 1.17 with increasing member thickness. In steel fibre-reinforced concrete, this ratio varied from 1.29 to 1.51, depending on the member thickness and the concrete strength.
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| 7. |
- Nilforoush, Rasoul, et al.
(författare)
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Influence of Surface Reinforcement, Member thickness and Cracked Concrete on Tensile Capacity of Anchor Bolts
- 2017
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Ingår i: ACI Structural Journal. - : American Concrete Institute. - 0889-3241 .- 1944-7361. ; 114:6, s. 1543-1556
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Tidskriftsartikel (refereegranskat)abstract
- An extensive numerical study was carried out to evaluate the influence of concrete member thickness and orthogonal surface reinforcement on the tensile capacity and performance of anchor bolts in uncracked concrete members. Anchor bolts at various embedment depths (hef=50 to 300 mm (1.97 to 11.81 in.)) in unreinforced and reinforced concrete members of various thicknesses (H=1.5 – 5.0∙hef) were simulated. The reinforced concrete slabs were considered to be lightly-reinforced and over-reinforced to evaluate also the influence of amount of reinforcement. Furthermore, the behavior of anchor bolts at various embedment depths in pre-cracked reinforced concrete members was numerically investigated. The numerical results were compared with predictions from current design models including the Concrete Capacity (CC) method.The numerical results show that in uncracked concrete the tensile capacity of anchor bolts increases up to 20% and the anchorage behavior becomes more ductile with increasing member thickness or by having surface reinforcement. The numerical results also show that the CC method underestimates the tensile capacity of deep anchors (hef≥200 mm (7.87 in.)), while it slightly overestimates the capacity of short anchors (hef≤100 mm (3.94 in.)) in thin unreinforced members. It was also found that the over-reinforced concrete does not improve the anchorage capacity and performance any further than the lightly-reinforced concrete. Based on the numerical results, several recommendations are proposed to account for the influence of member thickness, surface reinforcement and cracked concrete. Further experimental studies are ongoing to verify and generalize the recommendations of this study.
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| 8. |
- Nilforoush, Rasoul, et al.
(författare)
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Numerical and Experimental Evaluations of Influence of Member Thickness, Anchor Head Size, and Surface Reinforcement on Tensile Breakout Capacity of Anchor bolts
- 2017
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Ingår i: Connections between Steel and Concrete. - Stuttgart. - 9783945773062 ; , s. 752-764
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Konferensbidrag (refereegranskat)abstract
- The influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of cast-in-place headed anchors in uncracked concrete was studied both numerically and experimentally. The aim of this paper is to form a background for developing improved methods for the design of new fastenings as well as the assessment of current anchorages in practice. For this purpose, anchor bolts at various embedment depths (hef=50–500 mm) were simulated in plain and reinforced concrete members of various thicknesses (H=1.5–5.0∙hef). Three different head sizes of anchor bolts (i.e. small, medium and large) were also considered at each anchor embedment depth. Furthermore, to verify the numerical findings, a series of anchor pullout tests were carried out at which the testing parameters were similar to those in the numerical study.Numerical and experimental results show that the tensile breakout capacity of anchor bolts increases by increasing the member thickness or if surface reinforcement is present. The anchorage capacity further increases with increasing the anchor head size. The anchorage behavior becomes ductile by increasing member thickness or by having surface reinforcement, whereas it becomes stiff and more brittle by increasing the size of anchor head. To account for the influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of headed anchors, the CC method was modified and extended by incorporating three modification factors.
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| 9. |
- Nilforoush, Rasoul, et al.
(författare)
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Numerical Modelling and Experimental Verification of Pullout Loading of Anchor Bolts in Reinforced Concrete Structures
- 2016
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Ingår i: IABSE CONGRESS, STOCKHOLM, 2016. - CH - 8093 Zürich, Switzerland. - 9783857481444 ; , s. 2172-2178
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Konferensbidrag (refereegranskat)abstract
- The aim of this study is to provide a numerical model which can realistically present the failure load and failure mechanism of pullout loaded anchor bolts (headed studs) in reinforced concrete structures. The numerical analysis is carried out through a three-dimensional finite element (FE) code based on the Microplane constitutive law. The intension is to calibrate the FE model and to verify the numerical results against available test results. The calibrated FE model is intended to be used for an ongoing study to evaluate the influence of member thickness, surface reinforcement and size of anchor head on the tensile capacity and performance of anchor bolts.The simulation results showed very good agreements with the available test results. The objectivity of numerical modelling in respect to the size of finite elements as well as the defined boundary conditions was confirmed by additional numerical analyses.
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| 10. |
- Nilforoush, Rasoul, et al.
(författare)
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Sustained load performance of adhesive fastening systems in concrete
- 2017
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Ingår i: Life-Cycle of Engineering Systems. - Leiden : CRC Press/Balkema. - 9781138028470 ; , s. 2365-2371
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Konferensbidrag (refereegranskat)abstract
- Influence of several sustained loading levels and various in-service conditions on the long-term performance of adhesive bonded anchors are experimentally evaluated. Adhesive bonded anchors with 16 and 20 mm diameters were subjected to sustained load levels between approximately 23 and 70% of their mean ultimate short-term capacities. The creep deformation of tested adhesive anchors was monitored over approximately 28 years. The tested in-service conditions were indoor, outdoor, wetness (i.e. water on the surface of concrete) and presence in the concrete of salt additives. The tested adhesive anchors in the indoor conditions could carry sustained loads up to 47% of their mean ultimate short-term capacities. However, the adhesive anchors under outdoor environment showed larger creep deformations and failure occurred for anchors subjected to sustained loads higher than 23% of the anchors’ mean ultimate short-time capacities. Wet condition seemed to have no adverse effect on the anchors’ creep behavior, but caused corrosion of the steel in the anchors over time. Salt additives in concrete had negligible influence on the long-term performance and creep deformation of the tested adhesive anchors
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