Shear stress at different points of beam

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Discussion Overview

The discussion revolves around calculating shear stress at specific points (F and G) on a beam using the formula $$ \tau = VQ/It $$, with a focus on the application of this formula in a homework context.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents calculations for shear stress at points F and G, using the formula $$ \tau = VQ/It $$, and provides specific values for shear force (V), moment of inertia (Ixx), and the Q term.
  • The same participant expresses uncertainty about the correctness of their calculations, particularly regarding the values of Q and t.
  • Another participant suggests that for point G, the web thickness should be considered for vertical shear stress at a horizontal cut, indicating a potential oversight in the original calculations.
  • This participant also notes that for point F, a vertical cut should be taken to determine horizontal shear stress, implying a need for clarification in the approach used by the first participant.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the calculations presented. There are differing views on the appropriate approach to determining shear stress at points F and G, indicating unresolved aspects of the problem.

Contextual Notes

There is uncertainty regarding the definitions and assumptions related to the Q term and the thickness used in calculations. The discussion does not resolve these uncertainties.

fonseh
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Homework Statement


i'm not sure how to calculate the shear stress at point F and point G . I know that shear stress has formula of $$ \tau = VQ/It $$

The maximum shear force that i calculated earlier is V = 205kN , Ixx = 2.1x10^-4

for Q at $$\tau$$ at F , i have (205x10^3)(260x10^-3)(50x10^-3)(98.5-25)(10^-3) / (2.1x10^-4)(260x10^-3)

for Q at $$\tau$$ at G , i have (205x10^3)(250x10^-3)(50x10^-3)(50+125-98.5)(10^-3) / (2.1x10^-4)(260x10^-3)

Is my ans correct ?

Homework Equations

The Attempt at a Solution


The maximum shear force that i calculated earlier is V = 205kN , Ixx = 2.1x10^-4

for Q at $$\tau$$ at F , i have (205x10^3)(260x10^-3)(50x10^-3)(98.5-25)(10^-3) / (2.1x10^-4)(260x10^-3)

for Q at $$\tau$$ at G , i have (205x10^3)(250x10^-3)(50x10^-3)(50+125-98.5)(10^-3) / (2.1x10^-4)(260x10^-3)

Is my ans correct ?

I'm not sure whether my Q , and t correct or not . Can anybody check for me ?
 
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At G, you should be looking at the web thickness for vert shear stress at horiz cut, otherwise ok. At F , however, you should be taking a vertical cut for horiz shear stress determination.
 

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