Deflection

[McGill10]

Deflection limit for beam supporting masonry wall. As per masonry code the limit is L/600 or 0.3 in whichever controls.The later controls for beam span > 15 ft.
For most of our works, we use only the L/600 limit ignoring the 0.3 in limit and we are not having any issues. But we are violating the codes.
Just want to know how, you all are handling the similar cases in your day -to day works.
thanks in advanced.

 

[enginerding]

I always stick with the 0.3" limit where it governs. There are a number of things that can happen that can cause cracking in that wall. You don't want someone to see that the deflection is greater that the code maximum and blame you for it. Even if you can prove that the cracks were caused by some other reason, you will be stuck with the liability because you exceeded code maximum deflection.

I agree that the 0.3" does not seem to have much basis and is somewhat arbitrary, but it is the code.

 

[Lion06]

I ignore the 0.3" limit. That is removed in ACI530-08 anyway. Only the L/600 limit remains.

 

[ishvaaag]

In Spain's CTE, RC Structures there's a limit for "active" deflection of 1 cm. This for masonry partitions, or even façades, would be only the deflection produced after placement of the masonry. I -for mid to low-rise- have seen the partitions built from top floor to bottom to minimize passing much load than assumed to the lower floor, that uses to be the cause of some typical attached masonry pathologies.

In steel we were quite stringent, limit was 1/500 for non-load bearing masonries and 1/1000 when some wall supported on steel was itself a structural wall made of masonry. This worked passably well except for fragile cracking of façades made of well cooked brick with rich mortar, that sometimes even at these limits showed some cracks, some of them not hairline. The limits were with whole service level load. Now the CTE has relieved these deflection controls for steel, and you likely nor will see in the check a full service level load nor 1/500 as limit. This has the curious result of letting for most cases the strength check to control; good economy but more bouncing floors. With the prior codes, almost always deflection control ruled the selection of the member for any significant span. It must be said, however, that the masonries allowed by the current CTE are more like reinforced brick panels with joints that masonry itself.

So check if the limit of 0.3" is for just active deflection, as here. For ordinary floors made of RC it rarely controls, here.

 

[DaveAtkins]

I also ignore the 0.3" limit. I have found that for long spans, the steel beam becomes enormous, just to meet this limit.

DaveAtkins