Rehabilitation of a damaged footing of a Steel structure.

I assume this is photo is outside the structure:



What does this same column/footing look like inside the structure?

Capital of this thread should be (Rehabilitation of heavily corroded steel column bases ) rather than (Rehabilitation of a damaged footing of a Steel structure) ...

Apparently , the column bases buried with soil at the outside of the bldg and probably the situation totally different at inside..

My preliminary opinion would be , provide new split column base 200-300 mm above the existing one and extend the pedestal for the new set up..


You may provide more details to get better responds..








Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

I guess you should do like "surgeon", cut the foot, and replace it with new one
i.e. made temporary shoring for each steel column replace the entire footing system and 50cm of column (base plate and I-section)
made new concrete footing and attach new base plate ---> new column splice ---> from there you could have some kind of insurance of structure life extending.
my guess your cost will be 20% from replacing the entire gable frame

Dear adn26
Thank you for everyone sharing his opinion here.
I Completely agree with you about using temporary shoring for each individual column.
A visual inspection outside of the structure ( as in the attached pictures of my post ) shows very heavy corrosion. So, the solution only cut the corroded part and replaced the entire footing system with a new column splice.
But, do you have any proposal to execute such temporary shoring for each column or could you guide me to any references?
Thanks in advance.

For the column bases, replacement may be the best option. It'll be an expensive and time consuming operation, though, so it may be worth investigating further. Have the surrounding construction cleared away and either clean using power tools or blast clean the corroded steel to see what's left. Perform an analysis and see if the remaining section is sufficient. If not, you may be able to reinforce what's there rather than replace it completely.

For shoring, depends on where you are and what's available. In the US, companies produce specialty shoring equipment and have on staff engineers. So I just identify the shoring loads in my design and the shoring contractor has his own engineer that designs the temporary works for installation. If that's not an option where you, just approach it like any other structure. It has to support gravity loads during demolition and construction, environmental loads (wind, earthquake, etc.), and lateral loads from environmental loads as well as basic stability.

That's not corrosion.

This is corrosion!



If the picture SRE posted is the only one we got it's impossible to say what to do as it cannot be said how much cross-section is lost. Cleaning it up first would be my first thing (wire wheel or as phamENG said sand-blast just don't be too aggressive).

Refaatfaraj said:

1) So, the solution only cut the corroded part and replaced the entire footing system with a new column splice.

2) ...could you guide me to any references?

3) A visual inspection outside of the structure ( as in the attached pictures of my post ) shows very heavy corrosion.

Click to expand...

1) If cost is not a concern... but there are usually other solutions.

2) There is no "book", web site, or software; each project is different.
The answer is old-fashion engineering... measure the building, make reasonable assumptions for structural member tributary areas / loads based on what can be seen and calculated. Study the geometry of the roof trusses, the floor, and other members to see where temporary supports can be used. Bring all this info together, apply engineering principles, use a generous safety factor and come up with a practical plan for stable temporary supports.

3) I asked you about inside the structure (for a reason)... but you didn't answer...
A close look at one of your photos seems to indicate the columns/concrete pedestals both outside and inside are similar:



If outside and inside are similar, and the concrete is in suitable condition for expected loading, consider:

A) Both inside and outside, remove exposed existing base plate and sandblast the column:



B) Both inside and outside, use base plates that are thick enough that they do not need stiffeners:



C) Both inside and outside, use wide-flange sections, several feet long, as columns. Bolt or weld the proposed wide-flange columns to the existing column:



Make the measurements and do the calcs to see if this suggestion is practical. It may NOT be practical, you have the information, not us.

I worked in heavy industry, not for an engineering firm. Unconventional repairs are common at our electric generating stations... to minimize unit down time (unplanned outages).
In general, don't remove existing structural members unless absolutely necessary. Unnecessary removal is an invitation for unintended consequences and cost overruns.

@SlideRuleEra

What does this same column/footing look like inside the structure?

I apologize for not replying to you’re above question. Because until now the contractor excavated at one foundation ( outside structure ) just for preliminary visual inspection. inside the bldg there is a reinforced slab on grade covering the foundations.
Thank you so much for your clarification and the nice proposal to support the existing column with a new one. But the financial issue as you mentioned, as well as the aesthetics prevent me to adopt this solution.
I am thinking to support the truss end connected to the column by the shoring tower while supporting the girts connected with a column by post shores. after that replace the entire footing system with a new column splice.

Refaatfauaj said:

But the financial issue as you mentioned, as well as the aesthetics prevent me to adopt this solution.

I am thinking to support the truss end connected to the column by the shoring tower while supporting the girts connected with a column by post shores. after that replace the entire footing system with a new column splice.

Click to expand...

..."replacing the entire footing system with a new column splice" will be less expensive, than leaving the existing footing system unchanged but reinforcing the existing columns?

I guess I don't understand your plan... that's ok.
Best Wishes.