March 3, 2021 at 6:40 am

Nedas

Subscriber

I have a data from reinforced concrete beam bending experiment. Beam was loaded be steps from 5 kNm, 6 kNm, 8 kNm ..... 26 kNm. The data collected from experiment was top of the beam concrete maximum strain and stress value. At 26 kNm beam collapsed. The there is analytical calculation method, which uses real concrete stress-strain relationship to calculate sections with or without cracks. So we calculated crack height, stress and strain values of this section and we want to compare results with numerical calculation, using FEM analysis with ANSYS.nSo we have:concrete stress-strain relationship, steel yield stress, geometry and calculated cracks height.nIn my model reinforcement is recalculated into specific heigth layer to match its area with rebars used in experiment. In experiment was used 2Ø14 mm rebars so I recalculated them into 3 mm height and 112 mm width (beam width) layer.nAs you mentioned I changed from deleting elements to using EKILL command, solution remain the same. I use EKILL command on specific number of elements to get precalculated crack height prof analytical calculations.nArc-length method also didn't give me solution, transient analysis either or maybe I didn't use right parameters for transient analysis.nI changed steel material model with increased tangent mpdulus. Also I added one more point in concrete strass-strain relationship that after it reaches its maximum, for example 25,6 MPa it goes further with some tangent (attached picture). But this also doesn't help for solution to converge.nAt the first step bending moment is 5 kNm, crack height at this moment is 85 mm. I recalculated bending moment into to concentrated forces (as I show in beam scheme). Should I do more loadsteps from 1 kNm, 2 kNm, 3 kNm till 5 kNm or this doesn't help to converge the solutions and if I try to write loadstep files it gives me error that LSWRITE can't be used with EKILL.nMaybe one of the problems is that there are no slip opportunity between rebar and concrete and when rebar deforms, concrete also deforms the same, because they have same nodes, which move the same. Hope you understand what I want to say.n