The purpose of this thesis is to investigate the degree of influence of holes in the web of steel beams with long spanson weakening of their bearing capacity. Making holes in the web of the beam generally reduces the bearing capacity of the beam. However, it might be necessary seen from both an architectural perspective as well as from a building services perspective by creating an opportunity for building installations. The objective of this thesis is to examine how much an I-beam can be weakened without sacrificing safety and functionality. The investigation has been done by using Finite Element Method through commercial software. The regulation for structural design of building structures in Sweden used to be specified in the document known as BKR. But this was replaced by the European norm Eurocode back in May 2011. Starting from the transition between the norms, it is essential to investigate and define whether they differ and if so, what the consequences are of these possible differences. A secondary objective is therefore to define possible differences in structural design calculations between Eurocode 3 and BSK 07, which are the design rules for dimensioning of steel structures with Eurocode respectively BKR. The thesis work has been carried out in collaboration with Bjerking AB. The thesis has been divided into three sections: load calculations, structural design of single elements and finally the impact of the weakening by holes on bearing capacity. The following three structural elements have been studied:  Welded I-beam Welded I-beam with weakenings Truss beam The results from the structural design show that Eurocode demands more calculations than the BKR. However, Eurocode has in almost all cases indicated lower degree of utilization. This will most likely lead to lower material costs since less dimensions of structural elements is achieved. Eurocode has also showed lower limit for the effect of shear buckling during the structural design for shear resistance. The results from the analysis of the impact of web weakening on bearing capacity show that circular holes lead to higher bearing capacity than quadratic holes. Furthermore, the results show that the shear resistance of the beam, in principle, proportionally decreases with the area loss of the beam web. Regarding normal stresses, the analysis show that the most critical points to be considered in circular holes are at the very top and the very bottom of the edges of the hole where the largest compression stresses and tension stresses occur. Weakening of an I-beam’s web will also increase the vertical deformation of the beam in serviceability limit state but this increase of deformation is very small. The study has for example showed that a welded I-beam with span of 30 meters, height of 1300 mm, web thickness of 15 mm, flange width of 400 mm and flange thickness of 20 mm can accommodate 23 centered circular holes with diameter of 800 mm and center distance of 1200 mm without sacrificing safety and functionality. These holes result in a weight reduction of the beam from 8290 kg to 6930 kg.

Planet Earth's climate naturally varies over time, however the rapid change that is now takingplace is due mainly to human influence. Buildings and real estate sector's emissions ofgreenhouse gases is responsible for approximately 20,6% of Sweden’s total emissions ofgreenhouse and 33% of energy used 2018. Therefore, energy efficiency, a reduction in energyand energy supply with a low effect on the environment are necessary to manage environmentalquality objectives. Steel production requires high temperatures, and thus high energy consumption, both for meltingand processing, which in turn produces carbon dioxide emission into the air. Steel recycling isa much-needed innovation to save energy and reduce the amount of emission of carbon dioxide.However, even greater energy savings, and a reduction in the effect on the environment, can beachieved by reusing steel components instead of recycling or producing new steel. Despite thelarge environmental incentive, only a very small proportion of Sweden's total structural steel isreused. To date the process for reusing steel components has been unclear and needs to be clarified. Amajor challenge in the process is to create a marketplace where suppliers and buyers can meet.The purpose of this report is to investigate the possibility of parametric design to develop a toolthat selects suitable reusable steel beams from hundreds of beams which fit into new contextsin accordance with certain desired conditions. This work results in a program or script, where the user specifies his/her values and requirementsthat will apply to the selected beam. Furthermore, the program shows the beams that meet therequirements of users and sorts them in an environmentally friendly order. This program isexpected to help designers select the right reusable beam in the right place in a new project. The script was created to handle I- and H-beams using the program Rhinoceros-Grasshopper asa platform for parametric design and calculation. The program includes calculations for crosssectionalclasses, uniaxial and multi-axial bending without regard to the phenomena of lateraltorsional buckling, and transverse force where shear buckling is considered. However, the scriptdoes not handle beams with cross-section class 4. In conclusion the result of this study, which is the script, shows that it is possible to develop aparametric tool that calculates, analyzes and selects the beams that best suit the user's needs andwhere the selected beams are displayed in an environmentally friendly order. Such a tool canalso facilitate the process of reusing steel beams. It saves time and money as compared toperforming the selection manually. In addition, it opens people’s eyes to new efficient methodsand ways of thinking in the field of reusing. It can also be considered as an incentive forincreased reuse of steel beams while reducing the negative effect on the environment and whilesaving energy and natural resources. / Världens utsläpp av växthusgaser har under en lång period ökat mycket och detta ställer ossinför en global utmaning. Bygg- och fastighetssektorns utsläpp står för cirka 20,6% av Sverigestotala utsläpp av växthusgaser och 33% av energianvändningen år 2018. Därför ärenergieffektivisering, minskad energiförbrukning och energitillförsel med låg påverkan påmiljön nödvändiga för att klara miljökvalitetsmålen. Ståltillverkning kräver höga temperaturer, och därmed hög energiförbrukning, både försmältning och bearbetning, vilket i sin tur ger en del utsläpp i luften. Återvinning av stål är enbra strategi för att spara energi och minska mängden utsläpp av växthusgaser. Men ännu störreenergibesparingar, och minskning av miljöpåverkan, kan uppnås om stålkomponenteråteranvänds i stället för att återvinna eller tillverka nytt stål. Trots det stora miljöincitamentetåterbrukas väldigt liten andel av Sveriges totala konstruktionsstål. Processen för återbruk av stålkomponenter ser otydlig ut och den behöver fastställas. En storutmaning i processen ligger i att skapa en marknadsplats där säljare och köpare kan mötas. Dettahar en stark koppling till syftet med rapporten som är att utreda möjligheten med parametriskdesign att ta fram ett verktyg som väljer ut lämpliga återbrukbara stålbalkar av en databas nedett stort antal balkar, som passar in i nya sammanhang efter vissa önskade förutsättningar. Resultatet av arbetet blir ett verktyg eller skript, där användaren anger sina värden och krav somkommer att ställas på den utvalda balken. Vidare visar skriptet de balkar som klarar av kravenfrån användaren och sedan sorterar dem med avseende på minimal miljöpåverkan. Programmetförväntas hjälpa konstruktörerna att välja ut rätt återbrukbara balk till rätt plats i ett nyttsammanhang. Det framtagna verktyget är skapat för att hantera I- och H-balkar med hjälp av programmenRhinoceros-Grasshopper som en plattform för en parametrisk design och beräkning. Iprogrammet ingår beräkningar för tvärsnittklasser, enaxlig och fleraxlig böjning utan hänsyn tillvippning samt tvärkraft där hänsyn tas till skjuvbuckling. Skriptet hanterar dock inte balkar medtvärsnittklass 4. Resultatet av denna studie, vilket är skriptet, visar att det är praktiskt möjligt att ta fram ettparametriskt verktyg som beräknar, analyserar och väljer ut de balkar som passar bäst föranvändarens behov. Verktyget kan även underlätta processen för återbruk av stålbalkar,eftersom det sparar tid och pengar jämfört med ett manuellt urval. Dessutom öppnar det ögonenför nya effektiva arbeten och tänkesätt inom området återbruk. Det kan även anses vara ettincitament för en ökad återanvändning av stålbalkar och minskning av miljöpåverkan, vilketbidrar till energi- och resursbesparingar.

The contemporary imperative of sustainable development has established an unprecedented degree of urgency, in view of the intransigent challenges posed by the persistent and ever-increasing energy and climate crises. In 2019, the Swedish building industry accounted for 21% of the nation’s total greenhouse gas emissions, with the structural framework of a building contributing to 34% of its overall emissions. In response to climate change and the housing demand caused by a growing population, sustainable construction solutions are needed. By substituting steel beams with timber beams, the carbon emissions caused by the building industry can be reduced significantly. This study investigates whether timber based, or steel-reinforced timber beams can provide comparable load-bearing capacity to steel beams while reducing carbon. How this impacts the cross-sectional height of the beams is also taken into consideration. Different load-bearing properties were calculated according to Eurocode using Excel for all the surveyed beams. The carbon emissions were calculated based on the weight of each beam combined with climate data obtained from the Swedish National Board of Housing, Building and Planning. Findings suggest that timber-based beams made from glulam or laminated veneer lumber exhibit moment capacity and bending stiffness on par with those of steel beams while reducing the carbon emissions drastically, but at the cost of increased cross-section height. Steel beams were identified as the main source of carbon emissions. Consequently, also making steelreinforced timber beams only marginally successful in reducing carbon emissions if at all.