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Ram Concept Reinforcement Clause 8.1.5

Rhys Williams
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Hi there,

I'm relatively new to the program (a few months) and the firm I'm at sub-contracts pt detailed design. So we primarily use RAM in concern with deflections because usually a third party is contracted for detailed pt design. So its funny because RAM isn't really a preliminary design tool but something that gives great results (but requires input effort) and I'm not supposed to spend that much time on designs.

Anyway, my question is around the program reo. I've done a few different slabs and I keep getting a silly amount of reo in ductility design and the controlling criteria is 8.1.5.

Using the audit tool I can see it puts in up to 10% reo of the Ac before outputting that there's been a failure and so that reo on the plan is marked as red reo as opposed to green. I can appreciate that its shoving in compression reo to try and raise the neutral axis so that kuo is less than 0.36

but I just can't see the rhyme or reason to the areas that its doing it and there aren't big loads on it

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    Take a look at the program manual, section 60.6.7 Section 8.1.5 Ductility of Beams in Bending for details on how section 8.1.5. is implemented (in AS 3600-2009). It is noted that the challenge here is to simultaneously provide positive moment ductility and negative moment ductility.

    In one transaction we noted that in the calculation of the neutral axis depth ratio for AS 3600-2009, the effective depth "d" is used where the standard requires the use of do or maximum depth to reinforcement.  This is making ductility calculations for this standard conservative for cases with multiple layers of tension reinforcement. We are going to revise this aspect of the designer.

    We also acknowledge a need to change the strength design in AS-3600-2009 to have a variable phi factor based upon the actual strain in the cross section.  Then, in effect our ductility design can simply check to make sure that the largest neutral axis depth associated with the lower bound phi factor has not been exceeded. But, this will be a significant amount of work.

    Also see this post: 



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  • 0

    Take a look at the program manual, section 60.6.7 Section 8.1.5 Ductility of Beams in Bending for details on how section 8.1.5. is implemented (in AS 3600-2009). It is noted that the challenge here is to simultaneously provide positive moment ductility and negative moment ductility.

    In one transaction we noted that in the calculation of the neutral axis depth ratio for AS 3600-2009, the effective depth "d" is used where the standard requires the use of do or maximum depth to reinforcement.  This is making ductility calculations for this standard conservative for cases with multiple layers of tension reinforcement. We are going to revise this aspect of the designer.

    We also acknowledge a need to change the strength design in AS-3600-2009 to have a variable phi factor based upon the actual strain in the cross section.  Then, in effect our ductility design can simply check to make sure that the largest neutral axis depth associated with the lower bound phi factor has not been exceeded. But, this will be a significant amount of work.

    Also see this post: 



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