Steel I-Beams

consult a qualified civil engineer, or architect.

in most areas you are subject to building permits and inspection.

this isn't something one can guess on, safety first.

I'd pass on the architect...

I agree with Yosemit3, at least get a local engineer's advice on how to approach the problem. He/She will generally give this advice in a first meeting where he/she can get a first impression of the problem and then be able to give you an idea of the prices for the work and for the consultants' fees.

Note that the architect will eventually be useful as they need to sign-off on certain legal requirements.

I have building that needs a jack, what size jack do I need?

What do you mean 'sagging'!

If it's big enough to notice, you've got more serious issues than an add-on can fix.

I'd say, demolish the thing. No building, no problem.

Depending on the type of construction, a noticeable deflection may not be a cause for concern structurally. Many materials when used in a long span as a beam may deflect significantly before they are near failure stress. Most codes do proscribe limits on deflection for occupant comfort and to protect the things that the beam supports, but shoring a sagging beam is a viable solution more often than not.

Of course you are right.

I was being ironic, trying to discourage the OP from do-it-yourself ad-hoc solution of what may or may not indicate a serious problem. He shouldn't demolish anything right now. He should solicit expert help.

My angle is: Though not critical in itself, sagging is a problem indicator (it surely wasn't built to be like that). What the problem really is we cannot tell from here. And perhapds the building suffers from more problems than meet the eye. Then, if the OP is in a seismically active region, one cannot rule out the risk of a catastrophic failure. In 2000 it took a single earthquake in Turkey to wipe out several (hundred) densely inhabited poorly built structures. It turned out the quality of concrete was poor (contractor was cheapskate). I'll bet some of those were sagging too.

No, no DIY attitudes please!

p-x

I see your angle now - of course you should not attempt to correct a problem if you are unsure (and especially blissfully unaware!) of what the problem is! In such a case, bring in a professional. My experience is that it is much cheaper to hire someone than to exacerbate the problem, before finally bringing someone in.

Solicit bids for the repair, you will gain the info in the process.

IF the original support beam is STEEL, a much more economical 'repair' would be to temporarily jack the sagging beam to level with 2 jacks located 10 feet apart centered in the opening and then weld a 10' long 'doubler' strip to the bottom flange of the sagging beam extending each way from center to the jacks. I suggest using 3/16" thick steel strips the width of the lower flange for the doublers. Weld bead need not be continuous, but at least 25% coverage evenly distributed along the sides and length to ensure full tension load transfer. Relocate one jack 10' out and continue with another 10' doubler on that side. Weld the but joint and grind smooth. Replace the relocated jack, repeat doubler addition to other side. Relocate one jack to the center+6" Now weld second 10' long doubler to the first layer, starting 10' in from the end, reaching to the center. Relocate jack that was moved. Install 2nd layer doubler on the other side , again 10' in from end, reaching to other 2nd doubler. Weld butt joint and grind smooth. Then add 3rd layer , 10' long equally spanning the center section. This results in 3 layers at the most highly stressed center 10', 2 layers in the lower stressed mid section, and 1 layer of reinforcement in the still lower stressed outer sections. The outer-most 5' section probably does not need reinforcing to reduce sagging. If you feel it does, add it, welding the butt joints and adding a 1' splice plate also.

IF the original support beam is WOOD, and the side face is accessible, jack as before and using 1/4" lag screws the length of the wood beam thickness, bolt a 3/8" thick plate, width 1/2" less than wood beam depth, to the wood beam.

Drill 1/4" holes in a zig-zag pattern the length of the steel plate, holes 2' apart on each edge, 2" in from each edge. Drill 1/8" pilot holes in the wood, using the steel plate as the pattern. If it is easier to use 10' sections, at each joint (3), us a 2' long splice plate. Each side of the joint should have 6 bolts , located in pairs, staring 2" in from end of the splice, 2" in from top & bottom edges, and final 2 pairs 4" from the adjacent pair. Carefully lay-out, clamp, and predrill all holes, checking for fit before attempting to install the plates on the wood beam.

If only the bottom face of the wood beam is accessible, attach a 3/8" thick steel plate to the bottom face using 3/8" diax 3" long lag screws , with 5/16" pilot holes drilled in the wood beam. The holes in the steel plate should be zig-zag across the plate, staying 1" in from the sides of the wood beam. Hole spacing should be 18" along each edge. If splicing of the steel plate is needed, refer to splice details given above

W36 X 300 .-)

A1CASASNCASAS,

The critical information we need is missing: the load on the beam and its type. Any engineer or architect will start with determining this information. If the opening is in an outside entry to the building, it has to support the wall and any loads above it plus one half of the load on the area of floor or roof above. This half of the area is the width of the opening times one half of the distance from the opening to the next load-bearing or supporting structure inside the building at right angles to the opening. In addition to this "dead load", the support needs to also carry any additional "live load" from stored materials, people, snow, rain on a flat roof, etc. Furthermore, the long-term sagging of the structure is going to add an extra load to the beam if you are trying to reduce the amount of sag.

By type of load, you are dealing with whether this load is evenly distributed along the entire length of the beam, or if a part of the load is concentrated at some point along the beam (such as a piece of equipment or machinery, or a wall, etc.). The column supports at the ends of the beam must be sized for the load and stresses that such a load will place on the columns. These stresses include the compressive strength of the steel as well as ability of the column to resist sideways buckling. Also the foundation for the column must be capable of transferring this load into the underlying soil. If your new column is going to replace an existing one, the opening size is the same as before, and the existing floor shows no sign of sinking where the existing column is, then the foundation beneath is probably adequate. Otherwise, additional work will need to be done to maintain the structural integrity of the building.

As to the length and fabrication of the beam from sections, this is going to be a question of how to get it into position. A 40-foot long beam is fairly commonly able to be delivered to site by a steel beam supplier, as a single piece. The big question will be how to raise it into position--such as with blocking under its ends, or other means.

Finally, there is the topic of deflection hinted at in your original question, and mentioned by other responses. With wood beams, deflection over many years of age can be quite substantial before catastrophic failure occurs. With steel beams, deflection beyond a certain amount then subjects the beam to "yield" where the stress is beyond the beam's ability to safely carry the load. Deflection is stated in terms of a fraction of the beam's length. The maximum normally allowed is L/240 (which would translate as 1 inch of deflection for each 240-inches of length). Better is a standard of L/360 or even L/480. The amount of deflection you are willing to allow is determined by aesthetics and also by the type of load being supported (a brick or masonry facade to a building requires much less deflection than wood frame construction).

I don't know of any steel suppliers who will sell you a beam or columns for a specified load---this requires proper engineering design to answer the questions I have stated above, and as strongly mentioned by other answers to your question. The engineer will determine the load, its type, and the allowed deflection; then quickly give you the size of the beam required. Any supplier will take the specified beam size and column sizes and readily quote you the cost for the beam, its delivery, and even for erection if you desire it. Note, that for the specified load, load distribution, and deflection, a number of beam sizes can all be suitable--the taller the beam, the less it will weigh in pounds per foot (so its cost will be lower but the space it needs will be more).

In the USA, typical I beams are made to standards for wide flanges or narrow flanges. Most likely you will have a beam sized to the wide flange standards, so its size will begin with a W. The numbers that follow are going to be the height of the beam and its weight in pounds per lineal foot. Therefore a W8x24 beam is a standard wide-flange beam nominally 8" high, weighing 24 pounds per foot of length. Because it is made to a standard specification, it is very easy for an engineer's calculation and a steel supplier's salesperson to get you exactly what you want.

Work safely--John M.