Translations:Analysis of reinforced concrete with FEM/21/en

The required reinforcement is expressed in terms of a reinforcement ratio. This is the ratio of steel to concrete area. For example a reinforcement ratio of 0.01 in x-direction (rx=0.01) means that the total cross sectional area of reinforcement bars running in x direction should be 1% of the concrete cross sectional area they are passing through. A hypothetical cross section of 1mx1m should in that case contain 0.01 m2 steel, which could be achieved by using 90 reinforcement bars of 12mm diameter each (steel area = 90*PI*(0.012)^2/4=0.0102 m^2). If the required reinforcement ratio over this concrete cross section is uniform then the bars could be placed at an equidistance 9x10 grid with a center-to-center distance of approximately 10cm. This is still a practical number where sufficient space between bars is left for the concrete to pass through and ensure a high quality cover. Much higher values would lead to a very dense reinforcement grid with potential quality issues, whereas much lower values could lead to large tension cracks in the cross section between the bars. A typical range in practice is from 0.002 to 0.02 (= 0.2% to 2%). Further guidance can be found in design codes.