Muller R.,Tyrens AB |
Larsson S.,KTH Royal Institute of Technology |
Westerberg B.,Lulea University of Technology
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2013
During staged construction of embankments on clay foundations, the undrained shear strength su increases due to consolidation during the construction process. The increase is usually related to the pre-consolidation pressure σ′P by way of the ratio su/σ′P and is important when assessing the stability of an embankment. Properties controlling the increase are usually associated with various unknowns that can be difficult to predict before construction. A case involving a large embankment built on vertically drained sulfide clay is presented. Empirical knowledge and experience of similar constructions on sulfide clay were limited, therefore there were uncertainties of the soil-drain interaction and how the soil would behave under the embankment load. A trial embankment was built to gather knowledge and experience of this particular soil and the observational method was adopted. The study presents how embankment stability was predicted at design stage and controlled during construction. It highlights the importance and usefulness of obtaining measurement data from different types of measurements. Laboratory tests and a large number of in situ tests at different stages during construction were performed to assess su/σ′P ratios in the sulfide clay. The mean su/σ′P ratio was estimated by means of statistical analysis to 0.25 for a large stress interval.
Oqvist R.,Tyrens AB
INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control | Year: 2014
The variations in sound insulation are often large for lightweight constructions. A large number of measurements is therefore necessary to reliably evaluate the acoustical properties of a lightweight construction. The Swedish company Lindbäcks Bygg has since the '90s developed a timber system based on industrially prefabricated volumes. This paper presents a statistical evaluation of all measurements of impact and airborne sound insulation made on the system between 2011 and 2014. The objective was to quantify the variations in impact and airborne sound insulation in both weighted terms and 1/3 octave bands, and investigate the relationship between workmanship and acoustical properties. The study consists of a large number of vertical measurements between nominally identical room pairs. The measurements were grouped according to date, room size, floor level and assembly team. The variations were larger for impact than for airborne sound insulation. The impact sound level was higher in large rooms, which may have been caused by the method of joining several volumes. The sound insulation was somewhat better on higher floors. No significant differences could be identified between the different assembly teams. To improve the system, the impact sound insulation should be in focus.
Serrano E.,Linnaeus University |
Vessby J.,Linnaeus University |
Vessby J.,Tyrens AB |
Olsson A.,Linnaeus University
Journal of Structural Engineering (United States) | Year: 2012
This study relates to the topic of anchorage of shear walls. At times, eccentric forces between the sheathing and the anchoring devices may be introduced in the sill plate. In severe cases, such forces may cause the sill plate to split and to fail in a brittle manner. In this study, fracture mechanics are applied to develop a simple closed-form hand-calculation expression for estimation of the ultimate load capacity of the sill plate. Finite-element analyses using both linear elastic fracture mechanics (LEFM) theory and a nonlinear fictitious crack model are also used to predict the ultimate load-bearing capacity of the sill plate. The hand-calculation model is compared with the finite-element models, and good agreement is obtained. The results obtained with the various fracture mechanics models are compared with results available from previously performed experimental tests, and again good agreement is obtained. A general conclusion is that the LEFM theory is an adequate approach for the case studied and that the hand-calculation expression developed could be useful for structural design. © 2012 American Society of Civil Engineers.
Hedebratt J.,KTH Royal Institute of Technology |
Hedebratt J.,Tyrens AB |
Silfwerbrand J.,Swedish Cement and Concrete Research Institute
Materials and Structures/Materiaux et Constructions | Year: 2014
The aim of the short-term studies is to investigate the structural behaviour of pile supported slabs made of steel fibre concrete (SFC) only and combined reinforced steel fibre concrete. The studies include tests on an elevated slab where a combination of reinforcement bars and steel fibres have been used in one half of the slab and SFC only in the other half. The tests were performed on a column-supported elevated slab that simulates a half scale model of an industrial pile-supported floor slab. The short-term tests showed considerable structural and crack arresting performance that also increased with a higher dosage of fibres. A small addition of conventional reinforcement bars further increased the ultimate load capacity P Max. P Max was in the range of 125-298 kN for the two types of slab. The results indicate that SFC can be used with verifiable results in structural applications for elevated slabs and pile-supported floor slabs despite that the material testing from the ordered SFC showed a larger scatter in properties and that the calculated load capacities were only 40-220 kN. Main causes of deviance are arch and membrane effects. © 2013 RILEM.
Muller R.,Tyrens AB |
Larsson S.,KTH Royal Institute of Technology
Geotechnical and Geological Engineering | Year: 2012
The variation and anisotropy in hydraulic conductivity and the coefficient of consolidation was investigated for two Swedish sulphide clays. A series of constant rate of strain oedometer tests was performed on samples trimmed in the vertical and horizontal direction. A methodology to evaluate the horizontal coefficients of consolidation ch via the horizontal hydraulic conductivity kh and the vertical compression modulus Mv is proposed. Laboratory evaluations of ch are also compared with determinations of ch from in situ piezometer measurements in vertically drained sulphide clay. Furthermore, the validity of the empirical correlation between hydraulic conductivity change index Ck and initial void ratio e0, Ck = 0.5e0 (Tavenas et al. in Can Geotech J 20(4):645-660, 1983b), was investigated for the sulphide clays. The results from the investigation show large ranges in measured hydraulic conductivities and coefficients of consolidation. However, the results indicate that the correlation Ck = 0.5e0 is valid. The anisotropy in hydraulic conductivity and the coefficient of consolidation of the sulphide clays tested seems to be small. For design purposes, multiple tests for assessment of hydraulic conductivity and the coefficient of consolidation should be made, and a partial factor of safety, depending on the requisite level of safety and the spatial variability of the parameters, should be introduced. For design purposes in this type of clay, kh = kv and ch = cv are suggested. © 2011 Springer Science+Business Media B.V.
Magnusson J.,KTH Royal Institute of Technology |
Hallgreny M.,Tyrens AB |
Ansell A.,KTH Royal Institute of Technology
Magazine of Concrete Research | Year: 2010
The structural behaviour of concrete beams subjected to air blast loading was investigated. Beams of both highstrength concrete (HSC) and normal-strength concrete (NSC) were subjected to air blasts from explosives in a shock tube and for reference were also loaded statically. Concrete with nominal compressive strengths of 40, 100, 140, 150 and 200 MPa were used and a few beams also contained steel fibres. Furthermore, beams with two concrete layers of different strength were tested. All beams subjected to static loading failed in flexure. For some beam types, the failure mode in the dynamic tests differed from the failure mode in the corresponding static tests. In these cases, the failure mode changed from a ductile flexural failure in the static tests to a brittle shear failure in the dynamic tests. Beams without fibres and with high ratio of reinforcement exhibited shear failures in the dynamic tests. It was observed that the inclusion of steel fibres increased the shear strength and the ductility of the beams. The investigation indicates that beams subjected to air blast loading obtain an increased load capacity when compared with the corresponding beams subjected to static loading. © 2010 Thomas Telford Ltd.
Kagstrom M.,Swedish University of Agricultural Sciences |
Kagstrom M.,Tyrens AB
Environmental Impact Assessment Review | Year: 2016
Quality enhancement in environmental assessment tends to be connected to control mechanisms and best-practice guidelines. This paper takes an alternative approach examining quality performance through the lenses of consultants' perceptions of appropriate action, primarily in relation to the scoping phase. The study builds on interviews with Swedish consultants. The interviews are analysed by using a recently published theoretical framework focusing on practitioners' spaces for action. The analysis reveals that quality is highly open for interpretation and that consultants have a strong position for guiding quality performance, partly due to the key knowledge they hold. Their action is strongly guided by how the consultants perceive their responsibility; requiring a balance between maintaining good relationships with their clients through 'good enough' performance and maintaining a good professional reputation by undertaking what they themselves perceive as a 'best' practice. These findings indicate a need to reconsider the research in this field, promoting a shift of focus away from the dominance of quality enhancement measures and engage with issues of consultants' and other practitioners' perceptions of their responsibility in respect of quality performance. © 2016 Elsevier Inc.
Hojer M.,Tyrens AB
42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life | Year: 2013
The European-funded CityHush project starts from a vision: The quiet city! Implementing quiet zones with the help of quiet electric (or hybrid) vehicles, quiet tyres and road surfaces, as well as design solutions for buildings and noise barriers to mitigate low-frequency noise, the noise level inside the zone was expected to be reduced by more than 10 dB(A) units. Road traffic noise is the major noise problem in European cities. Changing to electric vehicles can bring about a significant noise reduction. In order to make the possible benefits tangible as early as possible - with only a small share of the vehicle fleet being electric in the beginning - CityHush was proposing quiet zones, so called Q-Zones. This paper summarizes the work performed during the three years long project performed by 15 European partners.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SST.2008.1.1.3. | Award Amount: 5.11M | Year: 2010
The CITYHUSH project will support city administrations in the production and implementation of noise action plans according to the directive EC 2002/49. The identified hot spots and noise acting plans made with the existing technology suffer from major shortcomings: 1. poor correlation between hot spots with annoyance and complaints; 2. most measures lead to increased emissions; 3. only indoor noise comfort is addressed. Step change solutions are proposed to reduce noise in the city environment. The project deals with developing suitable problem identification and evaluation tools and with designing and developing solutions for hot spots, which show high correlation with annoyance and complaints. Following innovative solutions and tools will be developed: 1. Concept of Q zones (zones in inner where only quiet low emission vehicles are tolerated). 2. Concept of parks embedded in Q zones. 3. Improved noise score rating models for indoors by integrating low frequency noise and the occurrence of high noise single events. 4. Noise score rating models for the outdoors. 5. Objective and psychoacoustic evaluation tool for low noise low emission vehicles. 6. Mathematical synthesis tool for noise from low noise low emission vehicles. 7. General performance noise specifications for low noise low emission vehicles. 8. Novel concepts for low noise roads based upon dense elastic road surfaces. 9. Novel concepts for low noise roads based upon grinding of asphalt top layers. 10. Novel concepts for tyres for low noise vehicles, including heavy vehicles. 11. Criteria for use of low noise motorcycles. 12. Active and passive noise attenuation measures within the tyre hood. 13. Solutions for high low frequency absorption at facades of buildings. 14. Solutions for high low frequency isolation in the propagation pad. All the above solutions and tools will be designed, prototyped and validated. They will result in obtaining the anticipated noise impacts.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SST.2013.1-1. | Award Amount: 3.56M | Year: 2013
The objective is to provide step changing track based noise mitigation systems and maintenance schemes, to provide reliable improved TSI based rolling noise calculation procedures with harmonized monitoring of the required input parameters and to provide track noise management tools, for use in noise mapping and hot spot action plans according to the END, for use as engineering tools and solutions in new railway projects and in refurbishment projects and for use by the track maintenance managers and track maintenance industry. The existing rolling noise models will be enhanced with new fundamental features: the integration of the low frequency noise emission and of the actual wheel rail contact conditions for more accurate predictions of the noise emitted by the track. On-board monitoring systems will be developed to make it possible to use the real roughness values and track decay rate values measured directly at the track location where maintenance action is required or where mitigating solutions have to be applied. New track solutions, including embedded track systems, will be developed which to yield a noise reduction performance of at least 6 dB(A) in comparison with the global rolling noise measured on a well maintained standard track in the network of the participating infra managers. The solutions will be applicable to tram, LRT and metro tracks as well as to conventional tracks in the whole European Union. The developed solutions should not back-up a poor initial design. This is why attention is paid to a good initial design with a procedure for selecting the best rail type and the best rail hardness in terms of minimising the noise related wear. A procedure for checking the economic viability of the solutions will be developed. This will result in holistic noise management plans for the introduction of the noise abatement solutions and for the noise related track maintenance.