Point Load vs Total Distributed Load

We need a better description, is the 5000Kg/ft^2 a posted load? is the 230kg/ft^2 a posted load. that one seems wrong or incomplete, either it should read "230kg", or "230kg/ft^2" with a size limitation.

If these are load capacities, posted by the structural engineer, you do not have to use all of that capacity.

By the way, 5000Kg/ft^2 is a huge floor load, should that be "5000Kg"? in terms that I "feel', that would be a more normal 100lbs/sqft over a 10' square area.

These units make no sense to me. First, Kg/ft^2 is a blend of metric and SAE units. Second, loading I thought should be the units of a force divided by an area. Kilograms is a standard unit of mass not force. The SAE unit of force (pounds (lbf)) is often confused with the SAE unit of mass (pounds (lb)).

well sorry my mistake it should be taken as 5000lbf as total load capacity of the floor and 250lbf/sqft as distributed load capacity

I'm really confused by the OP.....

It's too late, and I'm too dang tired to worry about it until I have my AM mug of Java....

Point load: load concentrated at a point.

Distributed load: load distributed over an area.

Hanging load: load supported at one end.

There's no need to be rude just because you don't know your own work and expect others to solve it for you.

I find the OP is exceptionally rude (just another "Camel Jockey" LOL), so he won't get any advice for me tomorrow morning.......I could have supplied him with the answer, but he FU'ed and let his filthy freaking fingers do the nasty. His loss, and as they say, "tough shit buster".....or better yet, "eat my shorts!"

i knw these terminologies read the first 1st post the main question is differnt and i knw my work as well but there has to be some decoram it is an intellectual discussion and should be serious one

Could I suggest you undertake a course in diplomacy.

After looking at your previous posts, one thing pervades them, you are down right rude!

This is complicated.

Lets take an elephant and a lady. Lets make an assumption here that the lady is trim and weighs significantly less than the elephant.

Put the lady into a pair of stilleto heel shoes and walk her across a wood floor.

Now let the elephant walk across the same floor.

Look at the results.

There will be small indents in the wood where the heel has pressed in. The point load has exceeded what the floor will stand.

The point load of the elephant has been spread over a much greater area and as such it will not have marked the floor.

If you have heavy equipment you need to spread the load, lots of legs or rails.

So we have the distributed load of the elephant is far in excess of the lady but due to foot ware the point load of the lady is greater than the elephant.

No units were involved here.

i have many server racks each of them weighs at least 1100lbf some are of 2700lbf as well if i sum all the loads on the floor it would be round about 9400Kg which is in the limit but when i start looking my distributed load it is 150lbf/sqft which might not be possibel for the load of 2700lbf rack

9400kg is approximately four times the allowable 5000lbs total. Your floor will sag and, perhaps, collapse.

well in TIA 942 the allowable distributed load on the floor must be with in 150lbf/sqft i have a room of dimension 30x24 ft and total weight on the floor is and total load on its floor is 20680lbf. if we calculate the load/sq.ft then it would be 28.7 lbf/sqft it is fine and with in the limit but i do not know what would be the limit for the point/concentrated load on the floor and does this comply with in the limits or not forget about the 5000lbf it is assumed value and wrong one. just tell me that as i am with in the limit of the distributed load on the floor what if my point load value goes beyond the limit i ll send u the drawing if u r still not getting my question

Moosie, Passington, Other Helpers,

Nabeel has made an effort to explain his misunderstanding of the numbers. And, Nabeel has sent along a drawing which I will attempt to paste in this note. I have done some calculations just because I wanted to use this as a little "homework" for myself to see if I could get it right. Nabeel is in trouble, I fear. I would like to ask you to confirm my calculations and either confirm my assertion that he can't do this at all, or that he needs an engineer and contractor to help re-build the structure, or something...

His room size is 1152 sq ft

His present load total is 30,150 pounds

His predicted future additional load is 13,500 pounds

Distributed Future Load would be 37.8 psf.

HOWEVER - well over 5/6ths of room is aisle space.

Concentrated Rack Rows increase loading in the rack spaces to over 190 psf.

While the total load is perhaps well within limits, without knowing the underlying beam structure and direction, etc. is it not possible these racks are concentrated loads many times higher than the floor can bear in these areas?

This all sits on a data center floor rated for 150 psf, which the data racks exceed, and the UPS racks by a large margin, which sit on a building floor rated for what I can best figure is 75 psf and perhaps is poorly built at that, which I think we must assume without more information. It's not that Nabeel's building is a piece of junk, it's just that we don't know, yet.

So... you both know I am not the SE, but using what you've taught me so far, I want to call this one - BUSTED. Did I get it right?

Bonus Solution - Is it possible that Nabeel might be better off - if the outer walls of the data center are the outer walls of the building - and he moved the racks closer to the outer walls, reducing the span distance from the perimeter of the structure? Of course, another question requiring more information, but on the face of it, would that help in a "typical" situation - move the loads closer to the supporting walls?

Nabeel - I'm not going to say you can't do this, it's not my place or my expertise. I am going to say I don't think you can do this, and - Please listen to Passingtongreen and CaptMoosie and the other professional engineers and whatever they say, do it. If they say I'm wrong, then we've both learned a good lesson.

Well the laying arrangments of the racks in the data center must be in aisles arrangments i.e. hot aisle and cold aisle that is the standard arrangement and must be followed well to my understanding if we change the arrangement by making lines of up to 4 racks per row . then would it solve the problem??

Texmedic is pretty darn close with his calculations and learned very well from the membership. I give him a GA for his posting!

I took a look at Table 4-1 of the ASCE Standard 7 "Minimum Design loads for Buildings and Other Structures", and the minimum Uniformly Distributed Live Load for "Computer Room Access Floor Systems" shall be 100 psf, whereas the minimum Concentrated Live Load shall be 2,000#. However, further down the same table, under "Office Space", it states that the structure supporting computer must be able to withstand future anticipated live loads of computer space; this appears to be the case here.

One items that Tex forgot to include in his calculations (which is alright and forgivable since he's not a SE and also a newbie at this ), is the inclusion of the Dead Load, in psf, which is imparted by the raised computer access flooring system.

Unfortunately, we haven't been given how the existing structure was built or what it was constructed of. To truly give the OP an answer is going to take a lot more than what we have to go on so far. I suspect that this is a reinforced concrete floor slab over a basement. OP? Do APPROVED CONSTRUCTION PLANS OR AS-BUILT PLANS of this building exist? And, do they detail how exactly to building was constructed, including notations of "FIELD CHANGES"?

First, we need to know the concrete compressive strength, in-situ, in the floor slab, girders, peripheral walls & columns. This is easily obtained by performing Windsor Probe testing of the concrete, a non-destructive form of testing.

Second, we need to know the arrangement, configuration, size and depth of the placed reinforcement bars in all of the affected reinforced concrete structural elements. This can be obtained using specifically designed ultrasonic testing equipment, again a non-destructive form of testing. Unfortunately, this test does not tells us what the steel reinforcement GRADE is, and can very tremendously from country to country and even within a country.

IMPO, this existing floor is incapable of provide enough strength to support the proposed computer equipment and appurtenances, based on what the OP has provided us so far, including the floor live load ratings. I still have not been given the source of the OP's Live load capacity numbers (see my earlier postings).

I have encountered a similar problem like this one in the past (some 20+ years ago_, where the State of New York wanted to install a new computer room on the 8th floor of a 25 story building in downtown Albany NY (the state Capital). The building was constructed circa 1927-ish, and the reinforced concrete floor slab, beams and girders were calculated to be incapable of supporting the proposed live loads. Yes, we had a professional testing agency do all of the aforementioned non-destructive testing.

The only solution was to install steel floor beams snuggled up under the existing concrete floor slab and attach them to the sides of the existing reinforced concrete floor girders w/ epoxy anchor bolts. Also, the top flanges of the new steel wide flange beams were secured to the underside to the floor slab (@ 24" o.c. spacing) with the same type epoxy anchor bolts to provide lateral stability of the top flanges (compression flanges) of each new beam. Additionally, the beams top flanges received a low slump cement-modified epoxy grout to account for any deviations or wavering of the underside of the existing floor slab surface.....they were not perfectly smooth nor flat.

All new beams were installed directly under the new raised computer access floor "strut" lines to ensure that the imparted loads from the computer equipment rested directly upon the new under-slung steel wide flange beams.

OP, you seriously need to obtain the professional services of a Registered Structural Engineer to help you. In my Professional Opinion, you cannot install your proposed computer equipment on this existing suspended floor slab without additional reinforcement.

get rid of the points - the little legs and put plates down - spread the load

You can spread your equipment weights by widening its foot prints. By making the total equivalent load to be distributed on a much larger and wider floor space /area. By doing this approach you increase the point load rated capacity of the floor.

point load capacity of the floor does not change. By making your footprint larger you effectively reduce your point load.

I'm on holiday from the electrical dept - come on guys you can crack this.

If this floor is a suspended reinforced concrete floor slab (is there a basement or crawl space under the floor?), then "punching shear" of the slab under a foot plate (ie, concentrated load from a support leg of a elevated false floor) must be checked by a SE to ensure that it is safe. This is something that a computer IT specialist isn't capable of determining....

Who exactly has determined the Allowable Live loads, as previously mentioned above by the OP, for this floor? I sure hope it wasn't the building owner or the superintendent!

I suspect we may have another incident like this in India soon. CR4 was never intended to replace professional oversight.

It never ceases to amaze me that this still happens around the world in this day and age. Wanna bet that no registered Structural Engineer was involved with this pool design (on a roof of all places!), and that not a single building permit for the construction was obtained and the plans reviewed!

Dangerous people trying to get away with what the last guy got away with! Too bad there was a death and several injuries involved with this particular failure....

Nabeel,

One very important concern is the pattern in which you lay out the racks in relation to the underlying structure.

If you gang the racks in a long single row and this row happens to line up in-between the beams and support columns below the room you could have a real mess on your hands.

Please read my offline note and respond back with more drawings and information.

PassingtonGreen and CaptnMoosie are EXPERTS in this field and when they are slightly nervous, you should be freaking out scared and looking for help - which is why you came to CR4, and that's good, but everyone needs more information and you will certainly need on-site professional assistance to get an absolute definitive answer to this problem.

TIA 942 is a standard, not a design. If this is an existing office or residential building, the floors are probably designed for less than 150psf.

I, and others, are mystified by all this confusing and contradictory information. I have, in the past, found that I could put some data centers into an existing office building by careful placement relative to the supporting steel and a little judicial reinforcement.

Appropriate photos, engineering/construction drawings, diagrams, appropriate dimensions in appropriate units, even a well thought-out sketch or two would be of great help in understanding what you're trying to say.

Put together as much of the above as you can, as soon as you can.

Then seek out an appropriate engineer in, or near, your location, if you are serious about getting real answers to your actual questions.

QED. GED(pending...)

pictures, dimensions and .......

and a job number!!

Whats this - free designs are us.

come on guys - give yourselves a shake!!

Nabeel,

Can you clarify on the following?

There are times what was labeled as 1st floor is actually the ground floor of the building. If the building has no basement level which is almost always below grade, the first floor becomes the concrete slab that sits right above the dirt ground.

Is the 1st. floor of your building situated on the same or a little bit above the street level? Is it like a concrete slab that was poured over the dirt or ground? is there any living space under or below that concrete floor where you want to install your system?

That vsar, is the question of the day (or is it this week?).

I've asked twice now for the very same clarification that you just asked.

IF it is a concrete slab on grade, meaning that the concrete was placed on dirt, then this essentially becomes a non-issue....of course if the slab on grade is too thin, then there will be possible problems.

If there is a basement floor or crawl space under this 1st floor slab, then I have my doubts about the existing slab being able to carry the Live Loads as described herein.

I have not seen any OP's response on that particular subject yet.. I concur that he may be just creating a mountain out of a mole hill if the 1st floor was just a slab poured directly over compacted dirt ?

vsar, my sentiments exactly....a mountain outta a mole hill if this is a slab on grade!

A different critter altogether if a suspended concrete slab.....I sense much danger there with the given Live loads!!!

CaptMoosie, you're correct and I concur 100% with your concerns.

Nabeel, please comment on your OP, because you asked about "hanging loads", which led many readers to suspect this was not slab on grade.

This, and the questions about "first floor" and "ground floor" have made it difficult for the CR4 experts to give any direction other than to seek the advice of an on-site professional structural engineer.

I think we are all enjoying the mental exercise of figuring out what happens when the UPS racks fall through the data floor, and whether that's a bigger problem than the whole floor and all the racks collapsing with the supporting floor and smashing the cafeteria in the basement - even worse right before lunch time.

Yes, "enjoying" is the wrong word. Change that to "engaged in".

please elaborate what exactly u want to know as frankly tell u i am an electrical expert not a civil expert please let me know ur querries so that i will verify the same directly from the client

Allow me to phrase the question in simple terms.

What is immediately below the concrete floor of this room? Below this concrete floor is there earth or is there an open space (basement, crawl space)?

this is first floor not ground floor

nabeel, we have here a cultural ambiguity. In the US the first floor is at ground level. This is why neither of my questions asked what floor level is your computer room. Please answer either of my questions about what is immediately below the floor of your computer room.

Tex, you hit the bullseye with your latest posting! GA from me for a concise explanation to overcome the cultural, language and technical barriers. I couldn't have said it better myself!!!

Just curious, are you a EMT by chance as well? I meant to ask this of you much earlier! :-) A man with many talents we're seeing here!

Thanks Moosie !!! for the GA! Made my day!!!

Yes, medic and instructor for 22 years now. Crunched kinda hard on the job. Crawled away, but 37 fractures left me wanting to do more but a little less than able. Working my way back to it. Meanwhile, I also do other work we've talked about.

Yeah, Yeah, OTP. Go ahead and ring me up CR4 madmen...

Glad to have made your day Tex! You earned the GA!

Wow, a medic and EMT instructor too? How many fiddles are you playing with there anyhow? I have nothing but respect for EMTs, nurses and doctors (well some doctors that is......).

37 fractures? Holy cows!!! Was that the farm tractor roll-over you mentioned once before? Having worked on my Great Uncles dairy farm summers as a teenager I got to thoroughly respect tractors. Dang things can be very dangerous! One of my other Great Uncles was killed when his tractor rolled-over on him. This happened in the early 50's before i was even born, but the lesson woke me up fast! Glad that you're on the mend!