Moment curvature in beams

[hesham ayman]

Dear DR. /Silvia Mazzoni,
I perform non-Linear time history analysis for a 2D frame (8 Stories, 4 bays) using fiber sections in all sections in the frame, and I start to monitor the curvature at different sections in the columns and in the beams to measure the ductility level and to identify the plastic hinge zones, I get a reasonable values for curvature in columns which approaches the maximum curvature – Section failure curvature- (Expected behavior regarding strong ground motion ), while I get a very small values for curvature in beams (values ≃ 10% of the maximum curvature ).
The expected curvature in beams is exceeding the maximum curvature to reflect the fact of plastic hinge formation in beams as per the “Strong column-Weak beam” concept which is fulfilled in the design.
Kindly note the following:
-Order used: Recorder Element -file elem2.out -ele 2 section 1 deformations
-Transformation type used in beams: geomTransf Linear 2
-Beam reinforcement: steel used in compression side = steel used in tension side to accommodate the +ve and the –ve moments in the section.
-Beams are subdivided into 5 parts (1.2meters each part).
Hesham Ayman,
M.Sc. researcher

[silvia]

the response you get sounds right, it just means that the elements were not designed properly to satisfy your design criteria.

[mch_basim]

Dear Mr.Ayman

I need some help, I'm doing a job like what you have done,
a 2D model with fiber sections, I want to know how can I record the curvature of elements at various sections.
In the order you have used I can't understand what is being recorded.
"Recorder Element -file elem2.out -ele 2 section 1 deformations"
please let me know what does deformations mean and what is the various columns in the recorded file.

I have some problem with plastic hing length too, which method you used?

Best regards
M Ch.Basim