# AREA LOAD and FLOOR LOAD

Hi Good Day STAAD GURUs

My questions are:

1. When using the AREA LOAD or FLOOR LOAD to represent the load beeing carried by the slab does STAAD automatically convert those loads to equivalent loads and then automatically impose those equivalent loads to the beams bordering the slab? or do i have to manually solve for the equivalent load then manually impose those loads (from the slab) to the beams. Actually thats what our instructor taught us, manually solve the equivalent load then put in on the beams supporting the slab. but doubt it[*-)]

2. On the command  "selfweight -1" does that selfweight include the weight of the slabs even if the slabs were simply modeled as plates?

ex: ....

meter kn

Element Incidences

1 1 2 3 4

Element Property

1 thickness 0.15

3. Attached file shows how to correct improperly connected plates. We added nodes 9 and 10 to beam 1 4 supporting plate 1 to correct the improper connection of plates 2 and 1. Just for discussion purposes lets us consider PLATE 1 before we break it into 3 plates as a TWO WAY slab. After breaking it to 3 slabs, the resulting plates from plate 1 are plates 3 4 and 5. Sir/Ma'am if i'm gonna load these slabs using FLOOR LOAD / AREA LOAD. Do i have to load them individually as one way for plates 3 and 5 then two way for plate 4? or should i just apply the floor load over these plates?

Thanks a lot

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• Hi,

1.

When you apply a floor load to a slab pannel, the programme calculates the equivalent load and apply the load to the beams bordering the slab as a uniformly distributed load. You do not have to calculate the equivalent load manually and apply them to the beams. Like in the attached figure a floor load of 10kN in the –GY direction is applied on the slab and the programme converts the load to equivalent distributed load and apply them to the beams.

Basically, the commands like Floor load or Area load are used when the entity transmitting the load, such as a slab, is not part of the structural model. The Area Load or One way Load may be used for modeling one-way distribution and the Floor Load may be used for modeling two-way distribution. For details please go through the Technical Referrence Mannual section 5.32.4.

2.

If you want to include the self weight of the plates then you have to assign the plates to the Self Weight command. The self weight command include the self weight of every active member and applied as a uniformly distributed member load.

The self weight of a plate is placed at the joints, regardless of plate releases. If you want to transfer the load from the plate to the connecting beam as a uniformly distributed load then you have to mesh the plate.

3.

As in your case you use plates in your model. So it is preferable to use “Plate Load” command in place of Floor Load or Area load command.

It is preferable to assign an area load for a one way slab. But there is no strict rule about this. You can assign a two way load also for those pannels.

If in your structure there are a number of one way slab, then you can create a Floor group considering those slabs and assign a one way load distribution for them.

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