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user277418

How to get REAL displacements in 3D steel frame with composite beams using FEA? Other words, how to model it rigth?

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Posted (edited)

Hello.

 

The question is in the title.

 

I tried to compare results from different software and little bit confused. I thought that results will be very similar, but in my opnion they are not. Description of the models and results below in DETAILS. Maybe something did wrong. Waiting for criticism and clues.

 

Archives with model files and calculations can be downloaded here >> https://www.dropbox.com/sh/o9f8upf3u1pvy6v/AAAH5CFhyjd8JdA7L9aCQ_r0a?dl=0

There everything is divided according to the programs.
 

Quote

DETAILS:

 

Modeling of a steel frame with composite beams in Consteel, Robot, ETABS and SCIA:

 

In all cases where the stiffness of the plate/diaphragm is required, a slab of 100 mm thickness is used from concrete C30/37. All data are described for wind loading (1.5 kN/m) applied to the columns. The movements are taken at the highest nodes of the columns from the side of the impact of the wind load. Where necessary the slabs are divided into final elements with a size of no more than 0.5 m. Displacements across the wind effect are fixed in all models. The stiffness of semi-rigid knots is determined with the help of the COP program (Sj,hogg = 34570 kNm/rad). External columns HEA240, internal HEB260. Beams IPE500. Steel S355. Ties in the level of each floor TCAR60x5 (located across the impact of the wind), steel S235. The length of the beams is 15 m, the step is 5 m. The height of each floor is 3.2 m. The outer columns are pinned in the bottom (freedom of all turns), internal rigidly fixed.

 

For comparison with the worst-case version of the frame, the HEB260 cantiliever column with a height of 12x3.2 = 38.4 m is modeled. It is understood that hinged beams, slabs and external columns do give any additional resistance to stability of the frame. The frame stability provided by the stiffness of the central columns and their fixed supports. The upper end is secured from the displacement across the force. The load is applied the same (1.5 kN/m). Moving of the upper end is 13012 mm.

 

Types of the models:
Robot 2017:
R1 - steel members and semi-rigid diaphragm without breaking into FE.
R2 - steel members and rigid diaphragm without breaking into FE.
R3 - steel members and shell with FE (the shell disfigure results of efforts in the beams).
R4 - pure steel frame
Consteel v9:
C1 - composite bars/beams without diaphragm.
C2 - steel beams with diaphragm without FE (the diaphragm disfigure results of efforts in the beams).
C3 - pure steel frame
ETABS v16.2:
E1 - steel beams with slab broken into FE.
E2 - steel beams and semi-rigid diaphragm without breaking into FE.
E3 - steel beams and a rigid diaphragm without breaking into the FE.
E4 - pure steel frame
SCIA v15.3:
S1 - steel beams with a composite slab broken into FE (not standard slab from concrete like in other models. In SCIA, it is impossible to use other types of the slab to achive composite action in the beams).
S2 - composite bars/beams (old SCIA module) without diaphragm.
S3 - composite bars/beams (old SCIA module) with a diaphragm of rigid arms (rigid arms).
S4 - pure steel frame

 

The results for 12-storey frame:

1. Connection of composite beams with columns is pinned.
Displacements of nodes:
R1 - 7016 mm
R2 - 17 mm
R3 - 173 mm. A warning about instability of the type 3, but the values of the displacements and angles of rotation of the model nodes are adequate.
R4 -
C1 - 4675 mm
C2 - 6965 mm
C3 -
E1 - 311 mm. Without warnings in the calculation log.
E2 - 9670 mm
E3 - 9660 mm
E4 -
S1 - 111 mm. Warning about the huge movements in some internal nodes of the plate (billions of mm and radians).
S2 - 7073 mm.
S3 - 19 mm
S4 -

2. Connection of composite beams with columns is semi-rigid.
Displacements of nodes:
R1 - 153 mm
R2 - 17 mm
R3 - 91 mm. A warning about instability of the type 3, but the values of the displacements and angles of rotation of the model nodes are adequate.
R4 - 180 mm
C1 - 102 mm
C2 - 117 mm
C3 - 153 mm
E1 - 104 mm. Without warnings in the calculation log.
E2 - 150 mm
E3 - 150 mm
E4 - 150 mm
S1 - 67 mm. Warning about the huge movements in some internal nodes of the plate (billions of mm and radians).
S2 - 110 mm.
S3 - 19 mm
S4 - 155 mm

 

Edited by user277418

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