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Assessment of sustainable mass management strategies in infrastructure projects - Application of the SCORE method in a case study of Lundbyleden
(2026) Said, Kamal
Large infrastructure projects often result in large amounts of excavated material. This raises important questions about handling, transport and opportunities for reuse. This thesis applies the SCORE (Sustainable Choice of Remediation) tool to the Lundbyleden project in Gothenburg to help guide sustainable management of these materials. Three mass management alternatives were compared: i) sending all the material to landfill, ii) sieving to allow for some reuse of masses, and iii) a combination of sieving and washing, increasing the reuse rate even more. Each alternative was assessed for its environmental, social and economic impacts to identify which best balanced the different aspects of sustainability. Further, three scenarios were developed to investigate the impact of different perspectives (sustainability vs. circular economy) and different references (“no action” or “landfill disposal”). The results, which were supported by Monte Carlo simulations, showed that treating the material to allow for reuse of masses generally gave better sustainability results than sending it directly to landfill. The results indicate that the most preferred alternative depends on the evaluation approach. From an environmental standpoint, sieving combined with washing had the best environmental performance, due to reduced landfill use, lower transportation impacts and greater reuse potential. On the other hand, from a circular economy perspective that considers both environmental and economic factors, sieving alone was more favourable, as it delivered environmental benefits at lower cost compared to washing. Including all sustainability dimensions resulted in considerable uncertainty, especially since the social dimension could only be assessed with limited data. The findings should therefore be interpreted as an assessment of circular mass management, rather than a full sustainability assessment. Although SCORE effectively structured the comparison, for infrastructure projects, referring to landfill disposal provides a more practical reference than ‘no action,’ as it mirrors actual decision making.
Resilience-Based Optimization of Rehabilitation Planning under Budget Constraints: Developing a Risk-Oriented Decision Model considering Supply Security
(2026) Raible, Marvin
Ensuring a reliable, long-term supply of drinking water is a significant challenge for municipal water utilities, particularly given strict budget constraints and challenging topographic conditions. This thesis aims to develop a transferable, risk-oriented optimization model for rehabilitating municipal water supply networks. The model evaluates renewal needs and financial sustainability. Through lifespan simulations, the model prioritizes specific pipeline sections using a risk-based, multi-criteria framework. This model is based on the concept of localized risk, which is defined as a function of structural failure probability and the resulting socioeconomic and physical consequences. The relevant evaluation criteria, including asset age, material generations, empirical damage rates, operating pressure, and traffic loads, are defined based on the technical guidelines of (DVGW e.V. W 403, 2025) and scientific literature. The Analytic Hierarchy Process (AHP) is systematically applied to determine the objective weighting of these conflicting criteria. Furthermore, this systematic approach establishes a mathematically reliable ratio of conditions to consequences, thereby eliminating qualitative biases. Based on the evaluated criteria, a risk index is derived to enable detailed prioritization of pipeline sections. Additionally, the model incorporates resilience indicators and consumer criticality metrics to account for the impact of potential pipeline failures on populations and infrastructure that are most vulnerable. The developed evaluation model was applied and validated using a real pipeline network in a Stadtwerke Freudenstadt case study. This application demonstrates that combining multi-criteria, risk-based prioritization with strategic rehabilitation planning under fixed financial constraints establishes a consistent, transparent, and structured basis for municipal decision-making. Furthermore, the model transforms local boundary conditions into a methodology that can be applied to other water utilities. The model provides a robust foundation for short-, medium-, and long-term rehabilitation planning.
Buckling Strength of steel piles Influence of imperfections, soil support, and elasto-plastic soil behaviour
(2026) Alhamad, Mahmoud; Osman, Ayel
Long slender displacement piles are widely used in soft clay deposits in Sweden, where the length-to-diameter ratio may exceed 100. Under these conditions, pile stability is strongly influenced by initial geometric imperfections, soil–structure interaction, and boundary conditions. Conventional analytical design approaches in Sween typically idealise the pile as a beam on a Winkler foundation, assume classical boundary conditions, adopt sinusoidal imperfection shapes, and represent the lateral subgrade stiffness as constant with depth. However, such simplifications may not adequately capture the behaviour of piles embedded in soft clay deposits with depth-dependent stiffness characteristics. This thesis investigates the geometrically non-linear behaviour of slender piles embedded in soft soil. The study focuses on evaluating the influence of initial geometric imperfections, imperfection mode shapes, soil stiffness distributions, and boundary conditions on the instability response of the pile–soil interaction system. Both constant and depth-dependent soil stiffness profiles are considered in the analyses. The influence of different boundary-condition configurations on the linear buck ling response is also examined. However, the geometrically non-linear analyses are limited to the pinned–pinned (P–P) configuration, since this boundary con dition consistently produces the lowest critical buckling resistance and therefore considered the most critical case for instability assessment. Theanalyses are performed numerically using the finite element software ABAQUS in combination with a Python-based automation script developed within the study. The pile is modelled using beam element, while the surrounding soil is represented using linear and bilinear Winkler-type springs distributed along the pile. Both lat eral and vertical soil springs are considered to represent the interaction between the pile and the surrounding soil, commonly referred to as soil–structure interac tion (SSI). This interaction governs how loads and deformations are transferred between the pile and the surrounding ground and has a major role in the stability behaviour of piles embedded in soft clay. Since there are no experimental data existing for direct comparison, the numerical models were first verified against analytical solutions for cases both with and without constant lateral and vertical soil support. Initial geometric imperfections were introduced using eigenmode shapes obtained from the linear buckling analyses. These imperfections were subsequently in corporated into the geometrically non-linear analyses in order to evaluate their influence on the instability response and ultimate load-carrying capacity of the pile–soil system. The elasto-plastic post-buckling behaviour was captured using the Static RIKS method, enabling investigation of the effect of imperfections and soil–structure interaction on the ultimate load-carrying behaviour of the analysed pile configurations. The results provide insight into the sensitivity of pile stability to imperfection shape and amplitude, soil stiffness distribution, and boundary conditions. The study highlights limitations associated with simplified design assumptions and contributes to a more realistic assessment of buckling resistance for slender piles embedded in soft soil
Fatigue Strength of Steel Beams with Corrugated Webs - Fatigue Assessment, Parametric Analysis and SCF Predictive Equation Development Using Effective Notch Stress Method
(2026) Alharami, Ghaith; Raad, Mohammad Sami
Corrugated web girders (CWGs) have gained increasing attention in bridge engineering due to their high structural efficiency and favorable weight-to-strength ratio. However, fatigue assessment remains challenging because the corrugated geometry induces local stress concentrations that cannot be adequately captured using conventional nominal stress approaches. Moreover, no generalized formulation currently exists to relate nominal stresses to local fatigue-critical stresses while accounting for key corrugation parameters. This thesis investigates the fatigue behavior of trapezoidal corrugated web girders (TCWGs) using the effective notch stress (ENS) approach. A detailed finite element (FE) model of a full corrugated web girder was developed and validated against four experimental tests. The validated model is subsequently simplified to a corrugated web beam representation (CWT: flange with corrugated web subjected to tension) while preserving an equivalent stress concentration factor (SCF). A comparison between the Hot Spot Stress and Effective Notch Stress methods was performed to identify the most suitable approach for further analyses. Based on this selection, an extensive parametric study covering a wide range of geometrical parameters was conducted, and the resulting numerical database was used to develop an equation for predicting SCFENS. The results showed that the corrugation angle, θ, and the bend radius-to-web thickness ratio, R/tw, are the governing parameters influencing SCFENS. Increasing R/tw reduced stress concentrations, with a more pronounced effect at larger corrugation angles. Regres sion equations developed from the FE results showed good agreement with the numerical database, achieving R2 values above 0.94. The proposed equations provide a practical tool for estimating effective notch stresses without refined FE analyses, supporting fatigue assessment and design optimization of trapezoidal corrugated web girders.
Comparative Design Analysis of Stainless-Steel Hollow Sections
(2026) Rosenberg, Andrew
Stainless steel hollow structural sections (HSS) are becoming increasingly popular in modern construction due to their favourable design properties. However, differences among international design standards can lead to variations in predicted member capacities and structural efficiency. A comparative analysis of different design approaches for stainless steel hollow sections based on four major structural standards: AISC 370-21, ASCE 8-22, Eurocode 1993-1-4, and the second-generation Eurocode (EN 1993-1-4:2025), was conducted to focus on how each standard addresses the determination of the bending resistance, global slenderness, and local slenderness, considering austenitic, ferritic, and duplex stainless-steel grades. A literature review of the different design standards and baseline information about stainless steel and its applications in structural engineering was first conducted and then a design tool for a parametrized study was implemented. Different design methods include the effective width method and direct strength method found in ASCE 8-22, effective width method from AISC 370-21 and Eurocode 1993 1-4, and the continuous strength method in both AISC 370-21 and Eurocode 1993 1-4 generation 2. Bending resistance calculations carried out across numerous sections of varying, height, width, thickness, and steel grades were compared to the slenderness of each section and the change in bending resistance for increasing slenderness is emphasized. Strength enhancements due to cold worked stainless steel was investigated and noted to play an important role in strength determinations when comparing standards. ASCE and AISC design codes become much more comparable with these strength enhancements factored in. The continuous strength method and direct strength method are dependent on global slenderness and does not work for all size sections. The comparison highlights the importance of knowing which method and standard is most applicable to a given situation. Overall methods found in AISC 370-21 showed higher resistances than ASCE 8-22 but similar in results and methodology to both generations of EN1993 1-4.