Design Strips, asymmetric columns, and Program Reinforcement

The model below was built using the Ram Concept Strip Wizard. There is only Latitudinal design strips. For the most part it seems to be working well except that there is an Analysis warning saying that the average slab coverage is 49.23% but i believe this can be ignored when dealing with slabs spanning in one direction?


The problem that i am encountering is when i rotate two of the columns 45 degrees, which is how they are in real life.

Rotating the columns means setting the design strips is a bit more complex. When i calculate load history deflections i get allot of analysis warning about small shear cores and program reinforcement with ridiculously small spacings.

Do all of these problems stem from incorrectly placed design strips and if so would anyone be able to assist me in regards to placing them more accurately.


Also i have found that when i have design strips that are on slight angles all my program reinforcement gets put in on weird angles aswell. Is there a way to override this and only allow program reinforcement to be put in straight and perpendicular to each other.


Any Information regarding this Matter would be greatly appreciated.


Kind Regards,


Matt

  • First, in regard to coverage, for a Load history analysis we are expecting design strips in both directions so that the element stiffness can be adjusted bi-directionally. In a single strip, where you only have design strips in one direction you will typically only have 50% coverage or less. You can still perform load history analysis of that slab, but be aware that and stiffness reduction are only be accounted for in the one direction.

    Your strip has some drops panels in it that complicate the design section geometry if the are not trimmed. Check out our wiki on design strip trimming for some details https://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/cross-section-trimming , but if you are planning to design and detail this as a flat slab (using the drops only for additional punching shear resistance), then trimming the strip to slab rectangle (or using an inter cross section slope limit of 0) is the simple answer. Rotating the columns is not really a significant factor here, though rotating the panels will be as some sections will then clip a small corner of those panels only.

    Use the skew angle tool (on the design strips layers) to keep the reinforcement aligned to the global direction even when the span segment lines are slightly skewed.