Dimensioning of Longitudinal Reinforcement for Serviceability Limit State Design 2
Tips & Tricks
In Part 1, we have described the selection of layout criteria for dimensioning reinforcement for the serviceability limit state design in RF‑CONCRETE Members and CONCRETE. Now, we go into detail for the function “Find economical reinforcement for crack width design.”
According to 7.3 in DIN EN 1992-1-1, it is possible to perform the design of crack widths in different ways. Allowable crack widths are considered to be given and designed according to Eurocode 2, if:
- The available crack width wk is smaller than the allowed limit value when calculating the crack width wk directly according to 7.3.4, or
- According to 7.3.3, without direct calculation of the crack width
- The limit diameter lim ds acc. to table 7.2 is larger than the available rebar diameter of the tension reinforcement, or
- The maximum rebar spacing lim sl acc. to table 7.3 is larger than the available rebar spacing of the tension reinforcement.
Therefore, it is sufficient for the crack width analysis when one of the design methods mentioned above is fulfilled. With the option “Find economical reinforcement for crack width design” you can check which one of the selected methods for crack width control (minimum 2 of 3) can be covered with an area of reinforcement that is as small as possible. Programs add reinforcement bars one after the other to the provided reinforcement until this design is fulfilled. The result tables 4.2 show the results for lim ds, lim sl and wk, even if only one limit value is governing for the crack width design.
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