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I'm currently trying to extend the shock-absorbing capabilities of a welded steel structure that is shown in the following image. It is a structure that supports a slat conveyor. A load is to fall approximately in the middle half of the structure. The base of the structure rests in a concrete foundation.

I need to expand the shock-absorbing capabilities because I'm worried about the structure failing due to pure impact forces. I'm not as worried by vibrations as by the maximum force exerted on it due to the impact. The load impact is difficult to quantify, even for a worst case scenario, but it is safe to say that the structure has resisted an impact force that is 25% lower than the one that is to fall now.

Welded steel structure

I would prefer not to change all the beam sizes, since the slat conveyor that rests on top of it is already assembled, but I could add some supports if needed.

According to Design of Welded Structures, however, making the beam span between supports shorter raises the impact stresses suffered by the structure, even if it lowers the static stresses (once the load is in place).Is there anything I can do to minimize these impact stresses?

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  • $\begingroup$ Can you please add why you want to extend the shock-absorbing feature? Is it because of the structure failing, or is it because of secondary effects, like vibration, harm to the falling load, etc. Are you allowed to cut and add shock absorbers to the legs? These would be useful information for better and more practical answers. $\endgroup$ – Gürkan Çetin Oct 7 '17 at 19:25
  • $\begingroup$ I added a second paragraph to my original description which hopefully clarifies things! Could you recommend sources to research structural shock absorbers, how they're installed, etc? Most of what I had found regarding them had more to do with cars than with structures. $\endgroup$ – gsolorzanop Oct 9 '17 at 15:09
  • $\begingroup$ Can you provide dimensions, masses, velocities or any detail that would help describe the scale of the system? $\endgroup$ – Donald Gibson Oct 9 '17 at 17:12
  • $\begingroup$ Can the conveyor handle the shocks? Can dampening be itroduced in the conveyor? $\endgroup$ – mart Oct 10 '17 at 14:37
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Large displacement shock absorbers used to dampen the effects of seismic events may be suitable for this application. These could be used to isolate the part of the structure that is grounded and the part that experiences the impact.

Seismic dampers sit between the ground slab and the building and can effectively reduce the shock loadings in all directions. Hydraulic dampers are often used to attenuate forces in a specific direction.

The dampers are available in many sizes and formats, from simple steel springs to sophisticated viscous piston systems.

Steel spring used in a building footing

Hydraulic dampers

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