Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Cracked cmu basement wall

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Will,

I agree with you. The existing deteriorated condition, which includes 
diagonal cracks at the top and horizontal cracks, is likely to be the 
result of a flexural overload of the wall and not due to the loss of 
support or settlement. Diagonal masonry cracks near the bottom of the wall 
are typically the result of settlement.

As Harold already mentioned various methods in his response, I have 
successfully strengthened deteriorated basement walls such as your case by 
employing the following methods. Both required a lot of work and thus not 
cheap either.

1.    Inserting rebars from the inside – cut vertical slots in the shell 
at 4 ft. o.c. then placed and grouted reinforcing bars into these slots. 
Please be aware that removing parts of the wall weakens the masonry because 
 the added grout in the cells does not participate in resisting the loads 
that are present. Therefore, the wall should be relieved of the existing 
loads to the greatest extent possible before this reinforcing takes place.

2.    Using external steel frames (but inside the basement) spanning 
vertically thereby reducing the effective height of the basement wall. The 
masonry spans horizontally between steel frames rather than vertically from 
 floor to floor. Caution – if the existing floors cannot provide adequate 
 bracing, the frames can be designed to span horizontally between new 
concrete or masonry piers. The existing masonry wall will then span 
vertically between new piers.

Mansoor Khan

-----Original Message-----
From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On 
Behalf Of Will Haynes Sent: Thursday, October 18, 2012 1:29 PM
To: seaint-seaosc(--nospam--at)mail-list.com
Subject: Re: [SEAINT-SEAOSC] Cracked cmu basement wall

Thanks Harold.

I told the owner the same thing yesterday about it being that old and 
comparing it to some older churches in the area and how they don't have to 
be brought up to code because a crack appears after 80 years. I asked and 
he said he needs a statement that the wall is structurally sound so that it 
 can be sold in the future. I wasn't trying to bring it up to code, but for 
 me to give an OK for the future of that wall I would like for it to have 
some rebar in it. The strongbacks are a good idea also.

I first also thought settlement caused the diagonal crack but the wall is 
pushed out of plane about 1/8" at most at the interface of the top side of 
the diagonal and the bottom. The top part of the wall above the diagonal is 
 sticking out.

The owner said the roots were pushing on the wall *at the diagonal crack

location* about 2.5 blocks down from the top of the wall. This is at about 
the same elevation as the long horizontal crack where it intersects the 
diagonal crack.

Truncated 1769 characters in the previous message to save energy.

-------------------------------------------------------------------------
Post your message to the list by sending it to: 
   SEAINT-SEAOSC(--nospam--at)mail-list.com.

The email messages sent to the list will be saved in an archive on the World Wide Web.
These archives are located at:
    http://archive.mail-list.com/SEAINT-SEAOSC

To contact the list owner, send your message to:
   SEAINT-SEAOSC-list-owner(--nospam--at)mail-list.com.

5700 Ralston Street, Suite 300, Ventura, CA 93003

To unsubscribe, switch to/from digest, get on/off vacation, or change your email address, click here.
http://cgi.mail-list.com/u?ln=seaint-seaosc&nm=seaintma%40euken.net