Sprickor i betongkonstruktioner kan ha en förödande effekt på konstruktioners säkerhet och stabilitet, men kan även göra att det blir en oangenäm syn att kolla på. Dessa sprickor orsakas utav dragspänningar i betongen som kan uppkomma som konsekvenser från olika typer av laster. Denna rapport fokuserar på spänningar orsakade utav en koncentrerad belastning på betongväggar. Syftet är att se hur spjälksprickor uppkommer och vilka åtgärder man kan göra mot detta med hjälp av armeringsbyglar eller armeringsstegar i betongväggar. Detta gör att målet blir att skapa en smidig beräkningsgång för att undersöka hur mycket armering som krävs och även se hur armeringsstegar kan användas för detta ändamål. För att ställa upp beräkningar så har fackverksanalogin använts och kraftspridningen har grund i kraftlinjemetoden för att denna metod ger en bra spegling av hur krafterna kommer att spridas i konstruktionens diskontinuitetszoner. Resultatet är en beräkningsgång av kontroller om det finns risk för att spjälkning och prägling förekommer och framtagandet av den erforderliga spjälkarmeringarea som behövs vid en koncentrerad last och hur denna ska placeras när risken finns. Armeringsstegar i skalväggar är inte att rekommendera för att de har en liten diameter och utbredningshöjden gör att det krävs många stegar för att klara av krafterna.

Purpose: Despite many previous articles and tests on the subject “analysis methods for concrete slabs on ground subjected to concentrated loading” there is still uncertainty on which analysis method to use and if the results correspond to real failure loads. The purpose of this study has been to evaluate and compare different analysis methods for slabs on ground subjected to concentrated loading.Method: Initially literature studies was performed where different analysis methods were studied. Three methods were chosen based on different aspects. It was found that A. Losbergs (1961) method was mainly used in Sweden while other countries in Europe used Meyerhofs (1962) method. Rao & Singhs (1986) method has a similar approach compared to Meyerhofs but ads two different types of failure modes. Two peer re-viewed articles were also chosen from which secondary data could be retrieved. The articles described tests where concrete slabs were loaded until failure. The test condi-tions were used to perform calculations with the three analysis methods. A comparison was made between the test results and the results from calculations.Findings: It is concluded that there are some differences between Losbergs, Meyerhofs and Rao & Singhs analysis methods. Largely the three methods require the same input, they differ in selection of analysis solution, but despite a degree of variation of the calculation results the overall picture for the different loading cases are quite unified. For central loading all analysis methods result in a capacity lower than the test values, varying from 56% to 93% of the failure load. Concerning edge and corner cases the spread of results is even wider. Calculations for the reinforced slab results in a capacity higher than the test values while calculations for the plain concrete slab results in a capacity considerably lower than the test values.Implications: The results in this study indicates that the three analysis methods are applicable for internal loading. The spread of the results makes it difficult to estimate the margin to the actual failure load, but the safety factors according to Eurocode 2 should provide a safe failure margin. Regarding edge and corner cases it is more diffi-cult to draw conclusions due to the large spread of results. Further research and testing is needed.Limitations: The study is limited to three analysis methods and the results from two articles where two different concrete slabs were tested. Inclusion of additional analysis methods and articles with test results would expand the generalizability of the study. However due to the limitations of the extent of the study and disposable time this was not possible.Keywords: Meyerhof, Rao & Singh, Losberg, concrete slab on ground, concrete slab on grade, point load, concentrated load.