| 51. |
- Hlal, Fatima, 1989
(författare)
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Stainless Steel Corrugated Web Girders for Composite Road Bridges: Concept Evaluation and Flange Buckling Resistance
- 2023
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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.
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| 52. |
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| 53. |
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| 54. |
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| 55. |
- Lanau, Maud, 1989, et al.
(författare)
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The Industrial Ecology of the Göteborg City Region — a first appraisal
- 2015
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Ingår i: International Society for Industrial Ecology 2015.
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Konferensbidrag (refereegranskat)abstract
- An infrastructure system – here, the industrial ecology of Gothenburg — is more important for society than we usually credit it for (cf. Technology is society made durable, Latour 1990) and is taken for granted by most inhabitants. Gothenburg is an unusually well-developed and interconnected infrastructure system. The first district heating facility was put in operation in 1952. Soon enough, waste was re-used and recycled into energy, into both electricity and heat. With time, more varied materials and sources became integrated into the system to also produce biogas and compost. The project makes a historiographic description of how the industrial ecology of the Gothenburg city region developed since the Gothenburg technical environmental flow system is unique in size, age, diversity of flows and functions. The study describes environmental flows and their actors in a networked organization. The focus on interconnectivity of the different actors, flows and sectors of Gothenburg requires the combination of several theoretical fields. Such theoretical fields include Networked Learning, which takes a relational stance in which learning takes place both in relation to others, and in relation to learning resources (Dirckinck-Homfeld et al., 2009); STS (Science Technology and Society), which study how technical innovation are affected by social, political and cultural values, and how these innovation affect, in turn, political, social and cultural values; (Joerges & Novotny, 2003); and Urban Metabolism, which uses models to facilitate the description and analysis of the flows of the energy and materials within cities, such as Material Flow Analysis of a city, and provides a metaphorical framework to study the interactions of natural and human systems in specific regions. Preliminary findings will be presented.
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| 56. |
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| 57. |
- Mangold, Mikael, 1982
(författare)
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The effect of resource sustainability interventions on social sustainable development in the built environment
- 2013
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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.
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| 58. |
- Nanukuttan, S. V., et al.
(författare)
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Taking performance to practice – simplified in situ approach for specifying concrete for chloride environments
- 2016
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Ingår i: fib Symposium. - 2617-4820. ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- The application of conservative structural codes such as EN1992 with high factors of safety and performance based compliance measures for concrete strength means that actual structural loading rarely exceeds the capacity and therefore has negligible influence on long term load carrying capacity. Majority of structures fail due to physical and chemical changes that concrete undergoes influenced by the exposure environment and subsequent reinforcement corrosion and loss of load carrying capacity. Lack of appreciation of concrete and its interactions with exposure environments, makes Designers and Engineers adhere more closely to prescriptive standards developed for relatively less aggressive environments. The data from exposure sites and real structures prove categorically that the prescriptive specifications are in adequate, especially for chloride environments. A performance-based approach similar to that followed for strength guarantee is proposed as a way forward for bringing durability into the forefront. For marine and de-icing salt environments, a handful of measurable parameters control the flow of chloride ions into concrete and such parameters form the core of most transport models. This article shows the scope of a simplified approach to chloride transport modelling using these core parameters for one chloride exposure environment. Further, the authors put forward a strong case for in situ measurements and the benefits it can have on assessing the whole structure. Examples for predicting the remaining service life as well as forming performance-based specification are also provided.
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| 59. |
- Othman, Sarbaz Najib, 1971, et al.
(författare)
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Are driving and overtaking on right curves more dangerous than on left curves?
- 2010
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Ingår i: Annals of advances in automotive medicine. - : Association for the Advancement of Automotive Medicine. - 1943-2461. ; 54, s. 253-264, s. 253-264
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that crashes on horizontal curves are a cause for concern in all countries due to the frequency and severity of crashes at curves compared to road tangents. A recent study of crashes in western Sweden reported a higher rate of crashes in right curves than left curves. To further understand this result, this paper reports the results of novel analyses of the responses of vehicles and drivers during negotiating and overtaking maneuvers on curves for right hand traffic. The overall objectives of the study were to find road parameters for curves that affect vehicle dynamic responses, to analyze these responses during overtaking maneuvers on curves, and to link the results with driver behavior for different curve directions. The studied road features were speed, super-elevation, radius and friction including their interactions, while the analyzed vehicle dynamic factors were lateral acceleration and yaw angular velocity. A simulation program, PC-Crash, has been used to simulate road parameters and vehicle response interaction in curves. Overtaking maneuvers have been simulated for all road feature combinations in a total of 108 runs. Analysis of variances (ANOVA) was performed, using two sided randomized block design, to find differences in vehicle responses for the curve parameters. To study driver response, a field test using an instrumented vehicle and 32 participants was reviewed as it contained longitudinal speed and acceleration data for analysis. The simulation results showed that road features affect overtaking performance in right and left curves differently. Overtaking on right curves was sensitive to radius and the interaction of radius with road condition; while overtaking on left curves was more sensitive to super-elevation. Comparisons of lateral acceleration and yaw angular velocity during these maneuvers showed different vehicle response configurations depending on curve direction and maneuver path. The field test experiments also showed that drivers behave differently depending on the curve direction where both speed and acceleration were higher on right than left curves. The implication of this study is that curve direction should be taken into consideration to a greater extent when designing and redesigning curves. It appears that the driver and the vehicle are influenced by different infrastructure factors depending on the curve direction. In addition, the results suggest that the vehicle dynamics response alone cannot explain the higher crash risk in right curves. Further studies of the links between driver, vehicle, and highway characteristics are needed, such as naturalistic driving studies, to identify the key safety indicators for highway safety.
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| 60. |
- Plos, Mario, 1963, et al.
(författare)
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Recommendations for Finite Element Analysis for Design of RC Slabs
- 2014
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Ingår i: Nordic Concrete Research. - 0800-6377. - 9788282080439 ; 2014:2, s. 39-42
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Konferensbidrag (refereegranskat)abstract
- The finite element method (FEM) is increasingly used for design of reinforced concrete structures. 3D FE analysis can provide more accurate structural analysis, but to use its full strength in daily design a number of critical issues have been addressed. Practical guidelines are provided for detailed design of reinforced concrete slabs. Recommendations are given on linear FE modelling, e.g. regarding geometry, support conditions and mesh density, as well as on the use of analysis results, e.g. regarding stress concentrations, choice of critical sections and redistribution widths for practical reinforcement design.
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