Hi. Thanks for the insightful video David. I have a query. For the curve segment 2, which has EI crack and the concrete and steel are still elastic...can they be classified as linear or nonlinear? Im wondering that it would be nonlinear as my understanding is that when the structure is unloaded the EI cracked doesn't go back to being the original state (EI uncracked). I associate the term 'linear' when the element can go back to its original state when being unloaded so..Am I right? :)
Per my understanding, non linear or linear is referred to the stress block we use in section calculation. At segment 1, concrete can undergo some tensile stress at its extreme tension fiber (despite being brittle material, they still have rupture strength fr or fct, etc, the name is vary according to each building code). During segment 2, tensile stress of concrete reach fr and crack and the reinforcements are kicked in to work. During these phases, we still have linear stress response in the section (you can see he stressed that one out at minute 3:10 in his video). Crack width is started to develope. This is how we do the crack check for service limit state, in some building code they have the stress limitation to check for crack instead of Mcr or crack width check. But in segment 3, the strain in concrete extreme compression fiber reach e,cu (= 0.003 or 0.0035 per code) and the reinforcement begin to yeild. You can see the compression stress block are NOT linear, and this is the phase we use in ULS capacity calculation (aka the equivalent Whitney stress block 0.85f'c along Beta1*c as mentioned in ACI code)
linear here means you can substitute area of steel |(As) for ( cracked section ) to an equivalent area of concrete e.g (n*As) then you can use hooke's law but that not the case if it is nonlinear.
I love this video, not only because it explains what I needed to know, but also because I love ASMR a lot :D
Can you give me an idea how to do section analysis for shear wall. or any example for reference?
Hi. Thanks for the insightful video David. I have a query.
For the curve segment 2, which has EI crack and the concrete and steel are still elastic...can they be classified as linear or nonlinear?
Im wondering that it would be nonlinear as my understanding is that when the structure is unloaded the EI cracked doesn't go back to being the original state (EI uncracked). I associate the term 'linear' when the element can go back to its original state when being unloaded so..Am I right?
:)
Per my understanding, non linear or linear is referred to the stress block we use in section calculation. At segment 1, concrete can undergo some tensile stress at its extreme tension fiber (despite being brittle material, they still have rupture strength fr or fct, etc, the name is vary according to each building code). During segment 2, tensile stress of concrete reach fr and crack and the reinforcements are kicked in to work. During these phases, we still have linear stress response in the section (you can see he stressed that one out at minute 3:10 in his video). Crack width is started to develope. This is how we do the crack check for service limit state, in some building code they have the stress limitation to check for crack instead of Mcr or crack width check.
But in segment 3, the strain in concrete extreme compression fiber reach e,cu (= 0.003 or 0.0035 per code) and the reinforcement begin to yeild. You can see the compression stress block are NOT linear, and this is the phase we use in ULS capacity calculation (aka the equivalent Whitney stress block 0.85f'c along Beta1*c as mentioned in ACI code)
linear here means you can substitute area of steel |(As) for ( cracked section ) to an equivalent area of concrete e.g (n*As) then you can use hooke's law but that not the case if it is nonlinear.
You can use that one to perform moment-curvature analysis on any R/C section: th-cam.com/video/4hCpEWjK4kw/w-d-xo.html
thanx
thanks