Precisering av vindlastens fördelning på en byggnad : Jämförelse av beräkningsmetodernas korrekthet
Sammanfattning: The wind load represents the biggest of the horizontal loads when calculating the stability of a building. It is important to design the building for this load so it does not tip over. How the wind load is distributed on the stabilizing walls can be calculated in different ways. In this report some of these methods are investigated. In those different calculations the walls take different amount of loads depending on their stiffness, placement or length etc. A reference house was used to appreciate which calculation method gives the best result. In method 1 the stiffness ratio between the floor and the walls decides how the distribution should be made. If the floor is stiffer than the walls, case 1, the loads are distributed to the walls depending on their stiffness. Stiffer wall means more loads. But if the walls are stiffer than the floor, case 2, the load will distributed on the walls like a beam on fixed supports. If the walls and the floor have relatively the same stiffness, case 3, the load will be distributed proportionally to the section of the facades carried by the walls. Method 2 is a simplified method where only the length of the wall decides how much load it will take. The longer the wall the more loads it will get. The reference house is then put into a computer based program, FEM-Design, where every floor in each direction is calculated one by one. This method is considered the most correct method in this report, and therefore the results from the other methods compared by this one to check their correctness. The results from the reference house show that one of the ways to calculate is more accurate than the others when compared to the model from FEM-Design. One of the cases from method 1 seems to be the most correct way to calculate, but it is not the same case as the one using the recommended method based on the stiffness ratio. Furthermore, the report shows that none of these methods reflect the realistic distribution fairly enough. They are all missing some aspect that should be into consideration. In method 1, case 1, the distance between the point of application of the force and the wall are not considered. And for case 2 and 3, method 1, the properties of the walls are not taken into account in the calculation. The results show that both the distance to the point of application of the force and the walls properties have a big impact on the wind load distribution. Keywords: Building stability, Wind load distribution, FEM, Stiffness ratio
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