Firstly i saw that someone else has asked a similar question but i was unable to grasp how to fix this problem from their answer.
The pictures below show the design strips in my model along with pictures of the top and bottom program reinforcement. After changing all the program reinforcement to user and running another load history deflection calc Ram Concept put more program reinforcement in (a lot actually and like 20mm spacing).
From the answer to the similar question i saw and the manual, this could be because.
The thing i don't understand is that when ram concept gives you its first lot of program reinforcement hasn't it already satisfied ACI 10.6.4. Why would simply changing the bars from program to user mean that the equilibrium of the cracked section it suddenly not balanced.
Any information regarding this matter would be greatly appreciated.
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This issue is associated with span detailing, in which the program extends top and bottom reinforcement to certain percentages of the span length. See Section 53.1 in the RAM Concept Manual for more information on span detailing.
In the initial design (without user reinforcement), a design is completed at each cross section and later an analysis on the required design. Span detailing happens as a post-process, so the analysis is not considering bar that is extended into the cross section to satisfy the detailing rule. Typically, adding bars during the detailing process increases strength or other code requirements, so the final layout with the extended bars is satisfactory. In this case, the span detailed bars are causing sections to become over reinforced, which then causes problems for the ductility check. When the program reinforcement is changed to user reinforcement, the program is considering the span detailed condition as the starting point, detecting that the section is over reinforced, and attempting to add more reinforcement to satisfy the ductility requirements. In the end, it is unable to do so.