Frame Works Trusses Homework: Determine Forces in Trusses

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Discussion Overview

The discussion revolves around determining the forces in a truss as part of a homework assignment. Participants are attempting to verify their calculations and compare results obtained through different methods, specifically focusing on the forces acting on the trusses.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant reports initial values for forces in the truss, including 100N tension and 187.5N compression, based on a lab measurement using a telescopic gauge.
  • Another participant calculates forces using the method of sections, arriving at values of 98.1N and 65.4N, which they note differ significantly from the lab values.
  • A request is made for the calculations leading to the 98.1N and 65.4N results, along with a reminder to consider the dead weight of the truss in the calculations.
  • A participant clarifies that they are neglecting the weight of the frame and plans to upload their working out later.

Areas of Agreement / Disagreement

Participants do not appear to reach consensus, as there are differing results from various methods and some uncertainty regarding the inclusion of the truss's dead weight in calculations.

Contextual Notes

Limitations include the absence of the truss diagram pending approval, which may affect the clarity of the discussion. Additionally, there is a lack of consensus on whether to include the weight of the truss in the calculations.

Colin Luu
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Homework Statement



I need to verify a couple of unknown forces in a truss, attached image (all individual trusses are 300mm in length)

Homework Equations


Determine the forces in trusses shown.


The Attempt at a Solution


This is a lab and I've used a telescopic gauge with a calibration chart to obtain a rough value of what the forces should be, (missed too many classes on Framworks damnit!)
From Left to Right Box, Left 100N Tension, Right 187.5N Compression RL is 163.5 N Rr is 130.8N
Even is i have a parallel worked example it would be enough.
 

Attachments

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okay I've done it with method of sections and resulted from left box to right 98.1N and 65.4N which is way off the lab value 187N for the right box can anyone verify these results?
 
Last edited:
We do not see the diagram yet while it is pending approval.
Could you supply your calculations how you obtained 98.1 and 65.4 N?
Have you taken into account the dead weight of the truss?
If the truss has only two pinned supports, you do not need to calculate by sections to get the reactions. Simply taking moments will do.
 
Sorry i forgot to mention this is neglecting frame weight, I'll scan the working out tonight and upload.
 

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