| 1. |
- Säwén, Toivo, 1993
(författare)
-
Early Stage Architectural Design Practice Perspectives on Life Cycle Building Performance Assessment
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Architectural practitioners can avoid negative social and environmental impacts of new construction by making decisions supported by impact quantification during design processes. However, most software tools developed for such quantification see little use in practice, especially in early design stages when decisions have the greatest influence. To identify ways for software developers to overcome this situation, a thorough literature meta-review of previously performed tool reviews was combined with interviews applying a practice lens. The first key finding is that a possible explanation for the low tool uptake in practice could be a missing practice perspective in previous tool development efforts. In a literature meta-review of publications on life cycle building performance tools identifying previously applied perspectives, most previous tool reviews were found to support tool development and selection, while disregarding how tools can be integrated in existing practices and design processes. As a proposed solution, a framework for defining software requirements using a practice perspective was developed. The second key finding is that a practice perspective could be applied during software development by implementing qualitative methodologies. Nine architectural practitioners in Sweden, Norway and France were interviewed using the interview to the double, a projective technique in which the interviewee is asked to describe their next workday in detail so that their tasks can be assumed by an imagined body double. The design activities described by the respondents were sequenced into user narratives which could serve as starting points for participatory software development processes within the architectural practice. The outcomes - a proposed framework for practice-centric software requirements, and a proposed methodology for collecting these requirements using a practice lens - indicate a research direction toward software development efforts which aligns with design process, architectural practice, and tool user needs. In the next stage of the research this direction will be pursued through application of the developed methodologies in participatory development case studies in early-stage architectural design practice.
|
|
| 2. |
- Adam, Abderisak, 1988
(författare)
-
Managing construction challenges: Viability of a dynamic capabilities approach for the public client
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Construction clients in the public sector face a large number of challenges in designing, procuring and managing construction projects in a manner that is conducive to the organization’s overall goals. In particular, clients have faced challenges in delivering projects that satisfied the projects’ goals with respect to cost overruns, delays and sustainable construction. The role of the client in managing these challenges has more recently been emphasized with a growing number of studies and governmental reports calling for the development of the client’s capabilities.This thesis examines the capabilities of the construction client through a dynamic capabilities framework, particularly with respect to the activities of sensing, seizing and transforming. Furthermore, the thesis explores whether the concept of dynamic capabilities is a viable approach for understanding how to manage the clients’ capabilities in a way that ensures that construction-related challenges are addressed. The thesis is based primarily on a case study of a large public construction client located in Sweden.Findings are presented in three appended papers. The thesis concludes with a discussion on the viability of using a dynamic capabilities framework in the specific case described in this thesis. It is argued that the concept of dynamic capabilities is inadequate for capturing the specific context in which public client organizations operate. Suggestions for alternative approaches to understanding the management and development of capabilities are then discussed.
|
|
| 3. |
- Estévez Mauriz, Laura, 1982
(författare)
-
The urban form and the sound environment - Tools and approaches
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cities are always confronted with transition and adaptation. Awareness on urban environmental quality is leading the vision about the built environment’s resilience and sustainability, highlighting the importance of a multidisciplinary framework for urbanisation processes. One of the main concerns is the negative impact of outdoor noise due to road traffic, whereby controlling the sound environment through good quality spatial production is a priority. Europe and other parts of the world are experiencing a chronic traffic congestion problem. The environmental impact of this situation is overwhelming, where 90 % of the health impact due to noise exposure is estimated to be caused by road traffic noise. In this regard, noise maps are seen as a powerful tool in the development of new urban areas, where its noise level underestimation can endanger the wellbeing of citizens. At this rapid urbanisation, divided pronouncements on decision-making are devastating. The aim is to overcome negative aspects derived from a late intervention by including urban sound planning as an opportunity to the user’s experience and wellbeing, avoiding poor patches in the urban configuration and economical burden. The present work is committed to the development of tools for controlling, communicating and designing the sound environment on a level beyond today’s solutions, capable to be included at the early stages of the planning process. First, the study goes through the importance of the quiet side and the implementation of an engineering method as a powerful tool in the urban development, obtaining accurate results compared to measurements. In an attempt to study time variations of traffic within cities and its relevance regarding noise emission (normally overlooked in current noise mapping calculations), a microscopic road traffic modelling tool is developed in the second study, giving useful output for noise level predictions as function of time. The time-pattern analysis opens the possibility to test traffic configurations and explore a large variety of results in the form of descriptors as statistical indicators, calm periods and noise events, and outcomes as difference maps and contribution maps. The third study extends toward the evaluation of the effects of spatial heterogeneity (considered a key strategy to increase the liveability of spaces) on the environmental performance and resilience capacity of the transportation system through the study of noise pollution and its economic impact. The studies presented are using real case scenarios as a test-bed not only for implementation, but mainly for the development of tools.
|
|
| 4. |
- Nasrollahi, Kourosh, 1991
(författare)
-
Differential railway track settlement in a transition zone – Field measurements and numerical simulations
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In a transition zone between two different railway track forms, there is a discontinuity in track structure leading to a gradient in track stiffness. Examples include transitions between different superstructures, e.g., slab track to ballasted track, and/or between different substructures, e.g., embankment to a bridge or tunnel structure. Differences in loading and support conditions at the interfaces between track superstructure and substructure on either side of the transition may lead to differential track settlement and an irregularity in longitudinal rail level soon after construction because of densification of ballast and consolidation in the subsoil. This results in an amplification of the dynamic traffic loading along the transition. To ensure the safety of railway operation and reduce maintenance costs, it is necessary to monitor the condition of the transition zone and detect any operational change at an early stage. A methodology for the simulation of long-term differential track settlement, the development of voided sleepers leading to a redistribution of rail seat loads, and the evolving irregularity in vertical track geometry at a transition between two track forms, is presented. For a prescribed traffic load, the accumulated settlement is predicted using an iterative approach. It is based on a time-domain model of vertical dynamic vehicle–track interaction to calculate the contact forces between sleepers and ballast in the short term. These are used in an empirical model to determine the long-term settlement of the ballast and subgrade below each sleeper. Gravity loads and state-dependent track conditions are accounted for. The methodology is applied to a transition zone between a ballasted track and a slab track that is subjected to heavy haul traffic. The influence of higher axle loads and the implementation of under sleeper pads on sleeper settlement is assessed. Based on fibre Bragg grating sensors, a setup for in-situ long-term condition monitoring of track bed degradation in a transition zone has been developed and implemented to provide data for verification and calibration of the simulation model. The system is designed for measurements in an operational railway track in harsh conditions in the north of Sweden. The instrumentation along the transition comprises four clusters, each with an optical strain gauge array on the rail web in one sleeper bay, and an accelerometer and a displacement transducer on the sleeper end. Two additional accelerometers are installed far from the transition zone to measure a reference state. Combined, the data should not only provide details on long-term settlements, but also the change in dynamic response it underpins.
|
|
| 5. |
- Dashti, Fatemeh, 1991
(författare)
-
A ground-borne noise prediction model for railway traffic in tunnels in bedrock
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Human life has become more manageable by the expansion of railway lines. However, despite providing convenience, railways increase noise and vibration in residential areas. Vibrations and noise generated by railways may harm human health, cause cosmetic damage and have an adverse impact on the environment. In order to reduce the effects of train-induced noise and vibration, efficient and accurate models for the prediction of ground-borne noise and vibration are required. Various analytical, theoretical, and experimental models have been developed to predict ground-borne noise. There is generally a lack of published information about parameters for ground-borne noise prediction concerning Swedish conditions with bedrock of high quality. Some investigations are reported, and a few consultancy companies have their own developed models, which are generally not publicly available. In fact, overall, the input data used to form these models and the methods of validation are not publicly available. Moreover, the statistical nature of the source and transfer paths requires that uncertainties are accurately handled in the model. This work aims to develop a model for ground-borne noise prediction for underground tunnels, to be used in Swedish Transport Administration projects. The methodology is formulated for three different stages based on precision and available information: location stage, planning stage, and construction stage. The first two stages correspond to planning and designing a railway track. The third stage involves the construction stage where more detailed information may be acquired. The prediction model presented here is developed for Swedish bedrock up to 1 kHz and formulated as a source term and several correction terms. These terms take into account various aspects, including train speed, distance attenuation, ground-to-building coupling, vibration levels on different floors and walls, how the room properties affect sound pressure levels within rooms, and different track treatments. Moreover, uncertainties are estimated using the standard deviation of each term. The required data are gathered from measurements in the Gårda tunnel in Gothenburg combined with existing data from measurements in the Åsa tunnel close to Varberg. As a result, a comprehensive model is suggested for ground-borne noise prediction in Swedish Transport Administration projects. However, the model is still under development, will be sent upon referral, and may undergo improvements.
|
|
| 6. |
- Domhagen, Fredrik, 1987
(författare)
-
Contaminant transport by air infiltration from crawl space to occupant area: Numerical simulations and field measurements in Swedish schools
- 2020
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Some Swedish school buildings built in the 1960’s and 1970’s have indoor air quality problems. Many of these buildings have a crawl space from which contaminants are suspected to originate. The poor indoor air quality cause discomfort among pupils and teachers and a solution to the problem is not always found. This thesis summarizes the work done on investigating contaminant transport driven by air leakage from the crawl space to the classroom in such buildings. Field measurements of temperature, wind, and pressure difference across the floor construction between classroom and crawl space has been conducted in two school buildings. A method in which frozen carbon dioxide is used to determine if air leakage to the classroom originates from the crawl space is also successfully tested. Also, a numerical infiltration model is developed in MATLAB and used to investigate how temperature, wind and air permeability distribution affect the pressure difference across the floor construction and contaminant concentrations. The numerical model is also used with the Monte Carlo method to investigate, for example, correlations between model parameters, such as air permeability and temperature, and to analyze measures, such as increased ventilation or use of an exhaust fan in the crawl space. Results presented in this thesis shows that outdoor temperature and wind has a stronger influence on the concentration levels indoors and the pressure difference across the floor than for example the building airtightness. For buildings with an imbalanced ventilation system, where the exhaust airflow is larger than the supply airflow the most critical weather case, in terms of high concentrations of contaminants indoors, is during mild and calm days. Numerical simulations also show that the pressure difference across the floor construction is positive (so that air leaks from the crawl space to the classroom) for most weather cases and building configurations.
|
|
| 7. |
- Fall, David, 1983
(författare)
-
Reinforcement in Tailor-made Concrete Structures
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In tailor-made concrete structures of complex geometries, the formability of concrete is an asset. To use this formability in load-bearing structures, the concrete needs to be reinforced. During the past century steel bars were used; however, in recent decades, alternative reinforcement methods have been introduced. To survey the applicability of several reinforcement methods, a literature review was made; the key findings are discussed. Despite the advantages of many of the alternative reinforcement materials, it was realised that conventional reinforcement is, in most application, the best alternative in terms of the structural integrity provided. Moreover, a major advantage of conventional reinforcement is that it is regulated in standards and design codes worldwide, which facilitates the application. The inclusion of steel fibres can provide additional structural integrity or, in some applications, replace the conventional reinforcement. As fibres do not require any concrete cover, this can be a solution for thinner sections.The geometry of tailor-made concrete structures can deviate considerably from the standard structural idealisations, e.g. beams and slabs. Hence, two methods for the design of conventional reinforcement, based on linear finite element analyses using shell elements, were investigated in order to enable a rational design procedure. Both methods, which rely on a sandwich analogy, make it possible to calculate in a rational way the amount of reinforcement needed in unique structures.To enable the use of steel fibre reinforcement in tailor-made concrete structures, the modelling techniques, including the non-linear behaviour of steel fibre concrete, need to be developed further. This topic was addressed in a study of fibre reinforced concrete beams, which compared experiments, FE analysis, and design according to fib Model Code 2010. Good agreement was shown when load-deection curves from experiments were compared with FE analysis; however, the design method presented in fib Model Code 2010 underestimated the capacity of these beams. The underestimation increased with increasing fibre contents. In addition to the investigation, future research is proposed; a rational design method is needed that should include several features not covered in the two methods discussed, e.g., the effect of inclined shear cracking, the choice of optimal reinforcement direction, optimization for production, and the inclusion of design with steel fibre reinforcement.
|
|
| 8. |
- Hlal, Fatima, 1989
(författare)
-
Stainless Steel Corrugated Web Girders for Composite Road Bridges: Concept Evaluation and Flange Buckling Resistance
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Achieving a sustainable bridge design requires careful consideration of economic viability and environmental impact over the entire lifespan of the structure. While stainless steel is recognized for its excellent life cycle performance, its high cost prevents it from being used to a larger extent in bridges. In this thesis work, a new solution is investigated to mitigate this issue. The new solution comprises the use of corrugated webs in stainless steel girders which is expected to result in reduced material consumption and cost. The work in this thesis focuses on two problem areas in this field. First, a study is performed to examine the competitiveness of the new concept in relation to conventional designs of steel-concrete composite road bridges. The second part of the work focuses on the problem of flange buckling in girders with corrugated webs. Previous research has shown that the design models developed for flange buckling resistance, including the one in EN 1993-1-5, frequently result in unsafe design. Furthermore, these models were developed for carbon steel and have not been updated for stainless steel. To explore the economic and environmental benefits of the new concept, two studies have been conducted. Firstly, three design solutions are examined on a case study bridge with three continuous spans. These design solutions include carbon steel flat web, stainless steel flat web, and stainless steel corrugated web girder bridges. A genetic algorithm is used to optimize each design solution in terms of weight. The three optimal solutions are then assessed in terms of investment costs, life cycle costs (LCC), and environmental life cycle impact. Secondly, two of the considered design solutions, namely carbon steel flat web and stainless-steel corrugated web girders, are employed to conduct multiple parametric studies using a simply supported reference bridge. For both design solutions, the effects of optimization targets on weight, investment cost, life cycle cost, and environmental life cycle impact are initially investigated. Following that, the focus is put on the life cycle cost (LCC) as an optimization target, and the impact of various design input parameters is investigated. These parameters include span length, girder depth, average daily traffic (ADT) with the associated number of heavy vehicles per slow lane (Nobs), and time intervals and expenses for maintenance activities. Furthermore, a sensitivity analysis is conducted to study the influence of the inflation rate and discount rate. The results indicate that the new concept offers considerable potential saving in weight, life cycle costs, and life cycle impacts for both simply supported and continuous bridges. The saving is more apparent with deeper girders, higher ADT, and more intense maintenance activities. Saving is also larger when inflation is high and discount rate is low. After studying the potential of corrugated web girders to reduce costs and environmental impacts in the case of employing stainless steel, a study of the flange buckling behaviour in duplex stainless-steel girders is conducted in this work. A parametric finite element model is developed and validated with tests conducted on beams made of carbon steel. The material is then changed to EN1.4162, and linear buckling analysis (LBA) and geometrically and materially nonlinear analysis with imperfections (GMNIA) are carried out on 410 girders with typical bridge girder dimensions. The results are compared to previously developed models for carbon steel, and a new buckling curve and flange local buckling design procedure for duplex stainless-steel girders with corrugated webs are proposed. The study shows that the new proposed design model generates more accurate estimates of flange buckling resistance than previous proposed models.
|
|
| 9. |
- Mangold, Mikael, 1982
(författare)
-
The effect of resource sustainability interventions on social sustainable development in the built environment
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are several sustainable development targets for the Swedish housing market. The sector as a whole is expected to contribute to the reduction of greenhouse gases. Housing prices should increase and not inflate. Meanwhile, the development of the built environment should contribute to well being and decrease segregation. Prioritization amongst these targets is often done through policy and by actors in the housing market. This thesis focuses on the trade-offs between environmental and social sustainable development targets. The thesis builds on two studies of development in the built environment. The main study describes an environmental upgrade of housing in a disadvantaged area of Gothenburg, and the second investigates a redevelopment area with high environmental ambitions. Environmental targets, such as CO2 reduction, have in some cases been profitably achieved in housing projects in Sweden. The principal study of this thesis describes the implementation of volumetric billing of water at Bredfjällsgatan which successfully reduced water usage and was profitable for the implementing real estate company. However, the system’s change also increased the average monthly costs for the households, and the average monthly costs increased even more in households where the inhabitants were unemployed. The lock-in effect of welfare dependency is increased by rising monthly expenses. This group lacks economic incentive to save water since welfare pays for water usage. The analyses of water consumption data show that while economic incentives account for some reduction of water consumption, other parameters such as household size, crowdedness of apartments, and household level of education are also important factors. Households receiving welfare are not economically affected by the implementation of volumetric billing of water but are further socially excluded from society when trapped in welfare dependence. The real estate owner states economic and environmental aspects as motivators for the system’s change. Social sustainable development targets on a societal level are not an outspoken priority to the same extent. The real estate owners in disadvantaged housing areas should be recognized as important actors in the development to tackle segregation of the housing market.The second study presents empirical insights from a housing area that is being built with high environmental ambitions. Perspectives of sustainable development amongst developers in the area differ, but it is apparent that social dimensions of sustainable development receive less attention. The complexity of social dimensions is not fully addressed. Social sustainable development is for example thought of as comfortable outdoor environments in the area, while the larger societal impacts of the housing project were not considered to the same extent. Integration, affordability, and equity were given direct focus; instead these targets are often assumed to be reached by varying apartment sizes and mixing tenure in the area.
|
|
| 10. |
- Pettersson, Kaj, 1990
(författare)
-
Modeling stormwater transport through unsaturated green roof substrates
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent decades there has been an increase in research regarding green roofs and similar technologies. This increased interest is driven by the requirements of urban development and its effects both on humans and the environment. Additionally, the predicted increase in weather severity in the future is raising concerns on the capabilities of urban environments and their stormwater management systems to cope with the increase. Green roofs can be used as a space-conscious solution for improving stormwater management in urban areas as well as contributing to, for example, building protection and pollution and noise reduction. In order to fully utilize them effectively for stormwater runoff reduction it is necessary to quantify their effect and optimize their performance in a given climate. This optimization can take the form of placement on structures or by design within the green roof construction itself. This work focuses on optimization of design by applying computational fluid dynamics and lattice Boltzmann theory to the soil growth substrate. Computational fluid dynamics is used for modeling the flow through the green roof growth substrate (soil layer) at the macrososcopic scale while a lattice Boltzmann model is applied to the mesoscopic (soil particle) scale. Using these methods, the efficacy at water retention and drainage of given soil particles and full-sized green roofs can be determined. This work covers the framework covering both scales however the methodology is applied only to the mesoscopic scale. The focus within the mesoscopic scale is primarily on the hydrophilicity of the particles in the soil and its impact on liquid imbibition. Also included is an exploration on the liquid-air interfacial area and liquid penetration depth to aid in the analysis of the results. The findings of the study suggest particle hydrophilicity plays an important role in the imbibition process, particularly under light to medium rainfall conditions. In addition a pore blocking phenomenon is identified which requires further analysis. Finally, plans for future work and the closure of the two-framework methodology proposed in this work is discussed.
|
|
