Introduction & Pump Foundation 1

[RattlinBog]

Good Evening,

I'm a long-time reader and first time poster. This is a great forum. I'm a structural EIT with a little over four years of experience. I started in consulting (mostly heavy industry work) but switched to the client side working at a mine less than a year ago. I'm the only structural on site, but there are a couple structural PEs at other mine sites under the same parent company. I'll be taking the PE exam in August. I'm also halfway through an M.S. Civil Engineering degree. I'm very slowly climbing out of the valley of despair of the Dunning-Kruger curve.

I thought it wouldn't be appropriate for my first post to be massive, but I could use some technical assistance. I'm designing a 'partial' foundation for a 250 HP pump. I say partial because we are reusing an existing 2'-8" deep foundation from an old pump, though I still need to analyze it for new loads. This is my first design for a foundation supporting dynamic equipment. (I am aware of ACI 351.3-18 but do not own a copy.) Below is a list of items I have or am planning to consider in my analysis and design. Would someone let me know if I should modify my list? It has occurred to me to contact the pump manufacturer about some of this, but I haven't done that yet.

Checklist:
- calculate forces on foundation and anchors from pump torque and thrust (I am factoring these forces by 3 to account for any harsh startups or other dynamics)
- compare concrete mass to equipment mass (a senior engineer I used to work with told me to size equipment foundations to be 2-3 times the mass of the equipment to mitigate vibration)
- design adhesive anchors per ACI 318 Ch. 17 (I have a Mathcad sheet but also plan to use Hilti Profis) (I'm assuming F1554 Gr. 36 threaded rods with snug-tight nuts and washers.)
- design sole plate beneath pump base for bending (assuming it loses contact with grout)
- determine installation details such as providing leveling screws or jam nuts to level sole plate; and providing a grout hole in sole plate
- spec grout (need to research if cement or epoxy grout is better suited here)
- check existing concrete foundation for shear, bearing, and possibly bending

What am I missing? As I get farther along in the design, I can provide more details and values. Thank you!

 

[RattlinBog]

Thanks Joel--I put the same engineering toolbox link up in the post before yours. I did use that calculator to double check my numbers, and everything worked out.

Joel, I'm currently going through the ACI 351.3R-11 that you provided (thanks again for that) and have a couple questions that maybe you could help with. Under section 3.2.2.1 Dynamic loads due to unbalanced masses--they provide a few different options to calculate these loads. I've decided to use eq. 3-7 (Sect. 3.2.2.1d Dynamic load determined from an empirical formula). See Fig. 1 below. Using Wr=5500 lb (weight of pump, probably conservative) and fo = 402 rpm; I'm getting Fo = 370 lb...which seems small. Maybe I'm just used to large structural loads in kips.

Q1: Does Fo=370 lb seem reasonable?
Q2: Am I understanding correctly that Fo acts as I have shown on Fig. 2 below?

Fig. 1
Fo = dynamic force amplitude [lbf]
Wr = rotating weight [lbf]
fo = operating speed [rpm]

Fig. 2