00:01
So in this question this is the figure given in the question so here in point e there is a pin support so because of this support there will be a vertical force let's name it as r ey that is this one and as well as there will be a horizontal force we named it as r e s that is this one and there is another support so in point f there is so pronal support so because of this support there will be a vertical force.
00:33
So this vertical reaction is named it as rf so now here to calculate the forces in each member we need to draw we first drawn this free body diagram of this ender trust and now let's apply the equilibrium incubitions so to calculate support reactions from symmetry you can write summation along x equal to zero gives you that along x the only thing is r a x so the r e s will be equal to zero and let's take momentum h e equal to zero so this gives you the value r f the distance to the r of is twelve minus this fifteen into the distance to 15 is 12 plus 12 plus 12 plus 12 that is 48 equal to 0 so from here we can write r f equal to 60 gives now let's take summation along y equal to 0 so that gives us r f minus r e y equal to 50 so we already got the value of rf so the only and only is ry so we can write the value for rriy will be equal to 45 keys you you got the values now there are theta 1 theta to theta 3 and theta 4 so let's find the angles so from figure theta 1 will be equal to an inverse of ch by cd that is 22 .62 degree now theta 2 .2 will be equal to the universe of bg by bc so this will be 39 .8 degree now theta 3 .3 will be equal to the inverse of the theta 3 that will be equal to inverse of a f by ab so a f by ab that is 51 .34 degree and now theta 4 will be equal to time inverse of this one ef by af, ef, sorry, a .f by ef, yeah, that will be a .f by e.
04:22
So that should be also 51 .34 degree as the a .f is same here and the ef and ab, the distance is same.
04:36
Like ef is also dual, the ab is also dual.
04:41
So that is same.
04:42
Now we found the angles.
04:46
Now use the join method to calculate the member forces.
04:50
So first for joint d.
05:01
For join d, this is joint d.
05:08
There will be 15 keeps, vertically downward.
05:15
And there will be, if this is d there will be f .d.
05:25
F and fdc so this is fd h and this will be fd c now let's calculate for 20 the summation of y summation along y equal to zero gives you fd sine h sine of each a 1 plus 15 equal to zero.
06:01
So from here the only unknown is fdh.
06:04
So we can directly write fdh equal to thirty nine keeps and fdh.
06:20
So as the value is negative here, so the actual value of fdh is inward that creates compression.
06:30
So that's denoted by the letter c.
06:34
Now summation of h equal to 0 gives you fdh course of theta 1 plus fdc equal to 0.
06:54
So we already got the value of fdh, substitute that value here.
06:58
That gives us the value for fdc.
07:04
That is 36 kits.
07:09
So here, ftc is going outward from the point d that creates tension, let's denote it by letter d.
07:18
Now we found for join d.
07:21
Now let's go to the next join, that is joined f...