Behavior of hollow beams under 4 point loading

Hi all,

I am analyzing RCC beams with longitudinal opening in various positions.

The ultimate load carrying capacity is supposed to reduce when the opening is moved to the compression zone than the solid control beam without opening. But the ultimate load carrying capacity was increased when the hole is provided at Neutral Axis and much more increased when the hole is at compression zone.

can anyone please explain me the correct way and the mistake I made?

I don't know what are the pictures I have to attach, so please tell me and I will attach it.

I have created 3D model in space claim, analyzed in static structural 4 point loading and load was applied as displacement as 0.01mm per step up to 0.8mm ( beam fails within 0.8mm displacement), standard earth gravity is applied.

Thank you.

Answers

  • AniketAniket Forum Coordinator

    Ansys staff can not download images on the student portal, so if you want to reach a larger audience to get answers from, please insert the images inline, using snipping tool and copy pasting it inline.

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  • I don't know what are the pictures i have to attach for the details, so can you please tell me what are pictures you want to explain the answer?


  • AniketAniket Forum Coordinator

    Images of geometry, materials being used, boundary conditions contacts and results that you get for different settings etc anything that would help explain your problem in more details.

    -Aniket

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  • edited November 20

    The above are the details of the analysis. the material assigned are concrete and structural steel with the same properties provided in the pictures.

    The force is shared from the top of the concrete and directly to the long bars and to the bottom.

    The beam is fixed at both ends. Load is applied in terms of displacement as 0.01mm per load step.

    First analysis

    The shared topology of loading plates and support plates are shared, concrete, stirupps and longitudinal rebars are provided with merged topology. the material assigned are general concrete and structural steel with the same properties provided in the pictures. The support condition is provided using plates at bottom such as four point loading system as one plate is fixed and other plate is free to move along longitudinal axis. The connections are bonded at first and the results of solid beam with bonded connections had satisfied the theoretical calculations. but for the hollow beams, the ultimate load carrying capacity is supposed to be reduced when compared to the solid beam, but the results of hollow beams shows the hollow beams are have more load carrying capacity than solid beams. Above all this, when the hole is moved above the neutral axis, means when moved to the compression zone of the beam, the load carrying capacity of the hollow beam have to be reduced more as per theories. but here it was increased.

    Changed Properties and steps

    Later, I have changed the materials as non linear materials and changed the connections between loading plate and concrete, concrete and longitudinal rebars and concrete to stirrups as frictional. The support condition is fixed at both the ends of concrete and the support plates are removed. the load carrying capacity of the solid beam is reduced more.

    As I am new to the analysis in ansys software, I don't know the reason for the above causes and I don't know the commands used for the analysis.

    Please explain me the reasons and the further changes I have to make to get the correct results. Willing to add some more explanations if I have to say about my works.

    Thank you

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