P-M Interaction diagram
P-M Interaction diagram
(OP)
It seems like explanations of most interaction diagrams leave out the portion where you have sufficient compression to overcome any tension in the section, i.e. c/d > 1 (distance from extreme fiber to neutral axis is beyond the edge of the section). How should these situations be handled? I'm looking for masonry and concrete references. Maybe it is just left out because it is a small piece of the diagram, but I can't seem to get passed it...






RE: P-M Interaction diagram
RE: P-M Interaction diagram
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: P-M Interaction diagram
Don't forget that everything above balanced condition line (yielding occur in same time as concrete crushing) is, in theory, a fragile rupture / Not ductile.
We accept it because we have more reserve in that zone due to safety factor in concrete being more important as the compression increase.
RE: P-M Interaction diagram
I suppose I have a series of questions I'm trying to understand. See attached for questions.
1. Applying the code, ACI (for concrete) and MSJC (for masonry) to determine the correct maximum nominal axial capacity and moment capacity when c/d is greater than 1 but less than infinite.
2. The best way to 'code' this into some sort of algorithm. Problem being is that I need to switch between 2 different ways to determine the moment when c/d > 1 and when it is less than 1. But I suppose that is OK.
Attached are my thoughts and I think I am having a hard time transitioning between strain vs stress and generic vs code.
Questions:
1. Concrete - when the equivalent stress block is greater than the depth of the section. In this case how do you determine moment capacity? The stress block is uniform and covers the entire section. Therefore how do you determine moment strength? There is no eccentricity. Even if the stress was not rectangular, what is the best way to handle this?
Any suggestions are appreciated.
EIT
www.HowToEngineer.com
RE: P-M Interaction diagram
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: P-M Interaction diagram
EIT
www.HowToEngineer.com
RE: P-M Interaction diagram
Then there will be zero moment when the stress block reaches the face with least compressive strain.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: P-M Interaction diagram
I missing something here.
EIT
www.HowToEngineer.com
RE: P-M Interaction diagram
RE: P-M Interaction diagram
Codes require a minimum load eccentricity (or equivalent procedure) so the axial load capacity to the code will be less than the theoretical maximum with no moment.
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/