Purpose: This study aims to identify three different types of house foundation. These house foundations are so called full basement foundation, crawlspace foundation and concrete slab foundation. When beginning a new construction, no matter if the house is small or large, there are many decisions that must be made. Including which foundation method is most suitable for the existing area. The house foundation must be able to stand firm for many years to come without suffering problems such as cracks and frost heave. It is important to choose at an early stage the foundation method that is most cost-effective and the ability to minimize the risks of frost heave. Method: The work is built up of two different methods; a literature study and a case study which contains several interviews with construction officials in Västerås region. Results: shows that concrete slab foundation is the primary construction that is chosen when choosing a house foundation for a new project aiming to build multiple single-family houses in Barkarö in Västerås city. All representatives decided that this construction has many advantages compared to the other house foundation methods, such as basement foundation and crawl space. It is the most proven basic method for this new construction of single-family houses. Conclusion: The conclusion of the thesis is that many of the representatives which works in the construction area choose concrete slab over other house foundations when there is no requirement for a specific house foundation from the customer.

Reinforced concrete slabs are a conventional type of foundation that is widely used in residential, commercial and industrial buildings. Most of the slab foundations are constructed directly on the ground without another structural medium in between and some of the slabs are therefore influenced by ground softening. A slab foundation is designed to transfer vertical loads and bridge imperfections in the ground, but excessive soil distortion may destroy the support conditions of the slab and through this influence the stability of the superstructures. The aim of this project is to study how ground softening and its further development influence a typical concrete slab. Furthermore, an approximate analytical method to evaluate the condition of a slab due to ground softening was studied. A practical case has been studied to capture the actual failure behaviours of a reinforced concrete slab, based on a previous project. For the case studied, possible future mining activities close to a high bay warehouse may cause damaging settlement in the underground. The fault that may appear softens the soils underneath the foundation, which may deteriorate and cause collapse of the concrete slab under the warehouse. Two types of failure scenarios were studied; subsoil softening and subsoil collapse. The Finite Element Method (FEM) was used to analyse the behaviour of the slab and the development of the failures in the subsoil. A commercial FEM software package, Abaqus, was used as the analytic tool, with a built-in Concrete Damaged Plasticity model (CDP) that for the concrete material model. Both linear and nonlinear material properties have been used in the analyses with same softening effect of the subsoil. A large number of models were analysed to simulate the development of the fault and capture the failure modes of the slab at different stages. Excessive tensile cracks and vertical deformations were found in both failure scenarios studied. A possible internal stability problem of the warehouse due to this was also found. The nonlinear behaviour of the concrete slab was captured through the failure scenarios before damage. It is shown that the serviceability of the reinforced concrete slab can be influenced by softening ground, and a more realistic description of the possible failures was here obtained based on the nonlinear model compared to previous elastic analyses. Keywords:     Reinforced concrete slab, Nonlinear, Ground softening, Finite Element Method (FEM), Abaqus, Concrete Damaged Plasticity (CDP). / Armerade betongplattor är en vanlig typ av fundament som ofta används för bostäder, kommersiella och industriella byggnader. De flesta av grundplattorna konstrueras direkt på marken utan andra strukturella medium emellan och vissa av plattorna påverkas därför av mjuknande undergrunder. En grundplatta är konstruerad för att överföra vertikala laster och överbrygga imperfektioner i marken, men stora sättningar i undergrunden kan förstöra plattans stödförhållanden och genom detta störa stabiliteten för överbyggnaderna. Syftet med projektet är att studera hur mjuknande undergrund och dess propagering påverkar en typisk betongplatta. Vidare används en approximativ analysmetod för att utvärdera tillståndet hos en platta på sådan mark. Ett praktiskt fall har studerats för att fånga det verkliga brottbeteendet hos en armerad betongplatta, vilket bygger på ett tidigare genomfört projekt. För det studerade fallet kan eventuell framtida gruvdrift nära ett höglager orsaka skadliga sättningar i undergrunden. Den förkastning som kan uppstå kan leda till uppmjukning av jordarna under fundamentet, vilket kan förvärras och orsaka kollaps av betongplattan under lagret. Två typer av brottscenarier studerades; uppmjuknande respektive full kollaps av undergrunden. Finita Element Metoden (FEM) användes för att analysera beteendet hos plattan och utvecklingen av fbrott och förskjutning i undergrunden. Ett kommersiellt FEM programpaket, Abaqus, användes som analytiskt verktyg, med en inbyggd plasticitets och skademodell (CDP) för att beskriva betongmaterialets egenskaper. Både linjärelastiska och icke-linjära materialegenskaper har använts i analyserna, för att simulera effekten av den mjukande undergrunnden. Ett stort antal modeller analyserades för att simulera skadepropageringen och fånga brottmoder i plattan genom olika skeden. Dragsprickor och vertikala deformationer uppstod i bägge de studerade scenariorna. Ett möjligt intern stabilitetsproblem hos lagret på grund av detta konstaterades också. Det olinjära beteendet hos betongplattan fångades fram tills allvarlig skada uppstod. Det visas att funktionen i bruksgränsstadiet hos den armerade betongplattan kan påverkas genom uppmjuknande undergrund, och att en mer realistisk beskrivning av möjliga brott här kunde erhållas genom den olinjära modellen, jämfört med tidigare elastiska analyser. Nyckelord:   Betongplatta , Icke-linjärt uppträdande, Finita Element Metoden (FEM), FE-modell, Abaqus, Plasticitets och skademodell för betong (CDP).