On modeling: How to properly consider heavy partition loads on model using Eurocodes?

[Epaenetus]

Hi,

I’m modeling and to analyze a building structure, following Eurocodes, using Etabs.

I just want to verify if I really need to load “heavy” partition walls, i.e. >3kN/m as per Eurocode, at the exact floor location as uniformly distributed load when doing the whole structure analysis. I'm finding it very tedious than just applying it as a surface load.

It is on my understanding that I need to consider the exact location of heavy partition walls when designing the slab, to which I can do a separate local analysis using Safe.

But for the whole structure, is it needed in Eurocode to account it as uniformly distributed load or I am allowed to just convert it to a surface load?

TIA.

 

[Agent666]

Well, don't you need to pickup the appropriate gravity loads on the beams supporting these walls so you are combining the correct gravity actions with the seismic actions?

In terms of overall mass for estimating period & overall response a UDL is ok. But for delving into the beams design actions under your Gravity + Earthquake cases, you need to know the gravity actions with sufficient accuracy.

For example if you had a heavy partition running perpendicular to the beam, it could cause a larger point load on the beam and possibly a positive moment hinge under the wall location when combined with seismic loads. With a UDL/area load by comparison you could see the positive moment hinge at the column face. Quite different scenarios and results.

A UDL isn't really going to produce the same design actions in the beams basically.

Typically in the past I think I have added a null line and applied the line load to that, as opposed to trying to model membrane slabs and dividing them or adding null areas on top of your slab. The null line will simply distribute the load applied to the supports as either a line load or point load depending on if it spans parallel or perpendicular to the beam. You can test in a smaller model and examine the 'display load' function and look at the load tributing to the frame members to show it is picking up the correct reactions from these null lines applied out in the membrane slab. This way if walls move as well for any reason you simply adjust the lines without needing to get into removing slab loads and reapplying them. Remember to test it first to ensure it is giving the desired results as sometimes null lines or areas have issues connecting to other stuff (use check model feature to identify if you have any loss of applied loads).