Engineering Problem or Greed Problem?
In first picture, in grey color, in good condition, you can see the old installations. There are 21 of them in which one of them got completely damaged into pieces. All of the others showing wear and tear due to years of use. But they still meet the basic requirement: you can sit on them.
In the second picture, in green colour, you can see the new installations. Out of 15, already 5 of them are broken as seen in the picture.
The bending moment diagram shows the new design supposed to have less BM at centre because of the fixed-fixed support. (Even after considering extra length between supports)
So, what went wrong in new design?
If you observe carefully, there is nut and bolt joint at support. Initially it might have behaved as per design. That is fixed-fixed beam. But because of negative bending moment at both ends, after few cycles, the joint might have lost its design intent. Now it is more like a simply supported beam with a higher BM at centre. So the same cross section might have failed because of change in support behaviour.
You may be thinking
just increase factor of safety
Or
Just add cement at required proportion
So
Is it an engineering problem or Greed Problem??
