Calculating Loads for a 2m x 2m Concrete Tunnel with 4 Supports

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Discussion Overview

The discussion revolves around calculating the loads for a concrete tunnel with specific dimensions and support conditions. Participants are addressing the dead load and live load calculations, as well as the ultimate state design load using given factors. The scope includes mathematical reasoning and technical explanation related to structural engineering.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Isabelle presents her calculations for the dead load and live load, detailing her approach to finding the cross-sectional area and volume of the concrete tunnel.
  • One participant questions the existence of a live load, suggesting that the problem statement may lack necessary details to justify it.
  • Isabelle clarifies that the live load is provided as 4kN/m² in the problem statement, indicating that she has supporting documentation.
  • Another participant expresses confusion about the meaning of "calculate the live load" when it is already specified in the problem.
  • A later reply indicates a realization of a mistake in reviewing the solutions, suggesting that there may have been a misunderstanding in the problem interpretation.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the necessity and interpretation of the live load in the problem. While some acknowledge its presence, others question its relevance based on the provided information.

Contextual Notes

There are unresolved aspects regarding the clarity of the problem statement and the assumptions made about the live load. The discussion reflects varying interpretations of the requirements for calculating loads.

Who May Find This Useful

Individuals interested in structural engineering, load calculations, and those working on similar problems in concrete design may find this discussion relevant.

curious_iza
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Hi I have tried this question and am struggling to work it out;

A concrete concrete tunnel with 2m x 2m dimensions on the outside (in cross section) with a uniform wall thickness of 200mm, is used to support a live load of 4kN/m^2 on its top surface. The density of the concrete is 25kN/m^3. The structure has 4 supports.

a) Calculate the dead load (G) and live load (Q) along its length in kN/m.

b) Calculate the ultimate state design load in kN/m of the concrete tunnel by applying the appropriate load factors of 1.2 and 1.5.

Obviously I have do work...

1) I got the cross section of the area which worked out to be 4m^2...

2) I then worked out the 'hollow' part since the thickness is only 200mm I got the 'empty' area as (2 - 0.2 -0.2)^2 = 2.56.

3) I subtracted this to get the actual cross section of the concrete.

4) I then made the length of the beam = Lm. And using the cross section and the Lm length I multiplied the cross section by the length to get the volume. Since density was given I multiplied volume by density and got 36L kN/m.

5) I then divided by L to get the force per m...

I don't know if I did all above right ... if so how do I tackle this question!

Thankyou for your time.

Kind regards, Isabelle
 

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What is there in your problem to give you a live load at all? Do you have some design spec that calls out a live load for you? Nothing you mentioned in the problem statement sounds like a live load at all. Something seems to be missing here.
 


Hi, they give the live load of the top layer (which is 4kN/m^2) ... I have attached the file with the exact question asked (If you would like a diagram). Thanks.
 


I was unable to open your pdf previously.

I'm not sure what "calculate the live load" means when it is given in the figure, but oh well ...

The dead load should simply be the total weigh per length.
 


Oh... hang on... I think I just figured it out - I looked at the wrong solutions. Typical. :D
 

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