Dimensionering av stålstomme och brandskyddsfärg vid en given brandteknisk klass

Sammanfattning: WSP Structures in Umeå wants the student to propose a preliminary design for a steel frame with a given input, considering the ultimate limit state and fire. The project has been limited to design the frame for the ultimate limit state and the fire design has been limited to calculate the amount of fire retardant paint needed for fire classification R30 for building components. The frame is delimited to columns, beams, horizontal stabilization and connecting joints between parts. With the help of theory, the resistance and the design amount of fire protection are verified, of which the results are verified.   As a solution, a model is created in the modeling software FEM-Design where load combinations are created by the given input and assumptions. Using the software´s design tool, the needed sections for columns and beams is calculated. Load effects that accords at joints is indicated by the program and is used to design joints and connections between parts according to SBI:s publications for beam-column connections and column footings. Most utilized elements were the “middle column”, which were designed to a HEA 200 profile with an 80% utilization. Detailed results are presented with tables which presents the utilization for each element. Designed columns, beams and joints can be found in level, section and detail drawings.   With the help of the created FEM model and used theory about fire design, the amount of fire retardant paint is calculated with the accidental load combination. The accidental load combination generates a lower utilization, which is used to calculate the needed amount of paint based on the manufacturer´s table. Columns received an amount of 750 g/m2 and beams received an amount of 1000 g/m2. Horizontal stabilizing elements didn´t receive any protection because it could be shown that columns could be calculated with a fixed support during the accidental load combination with a significant lower horizontal load.   The student thesis emphasizes the importance of finding a balance between the amount of paint and section and embracing a discussion about fire protection for joints. The utility rate for columns and beams became a guideline for the utility for joints since the amount of paint applied on the beam and connecting joints is the same, it would be a problem for example if the joint is utilized more than the connected beam. Also, determining the amount of paint needed is difficult if different steel grades are used in a joint and if details such as stiffeners are narrower than the thickness of the connecting column/beam.