# Structural mechanics-force diagram,shear stress,elastic curve

1. Nov 25, 2007

### wkh023002

There are totally 4 questions .i struggled for a whole day and i still cannot solve it.Please help me!
For Question 1:
My problem is that i cannot find out the reaction Ax,Ay,Dx,Dy though i establish 4 eqt:
1:Ax+Dx=90 kN
2:Ay+Dy=90 kN
3:summation Ma=0 ,anticlockwise positve
-125+2Dx+5Dy=0
4:summation Md=0 ,anticlockwise +ve
505-2Ax-5Ay=0

For Question 2:
i dunno what is the meaning of G=80kN/mm^2 and how to calculate the shear force?
also, what is Bredt-Batho theory? My professor haven't mentioned it so far.

For Question 4:
The first load from left P=WL/5 is outside the Y-axis, does it mean that i can neglect it?
to find the equation of elastic curve, do i need to establish the Moment equation for each section?

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2. Nov 25, 2007

### PhanthomJay

For question 1, in 2 dimensional frames, there are only 3 equations of statics external to the system that you can use in solving for external reactions...sum of Fx=0, sum of Fy=0, and sum of moments about any point = 0. The 4th equation you list is redundant. Since there are 4 unknowns, you must look at what is going on internal to the system to get your 4th equation. What do you know about the moment at the hinged joint C?

Last edited: Nov 25, 2007