ETABS 2015 Wind Load Path Question

[rbateman]

Question:

Attached to this email is a very small ETABS file I quickly made to express my problem understanding wind load path.

[URL unfurl="true"]http://files.engineering.com/getfile.aspx?folder=286b1e84-ec81-468a-b098-a01ad8abd4b1&file=windtest.EDB[/url]

The model consists of two continuous columns fixed to the ground and are connected by 4 simply supported beams. Between the beams and the columns are three null auto-cladding objects used specifically to apply wind loads. The use of these auto-cladding objects are inspired by watching the CSI ETABS “Watch and Learn” video tutorial on a steel structure. Wind pressures are applied to the null cladding objects. Observation of the analysis run will indicate that the auto-cladding elements transferred the load to the columns only. The beams do not transfer any wind load and they appear to be useless in the computed wind load path.

This is not the behavior I want to produce nor is it considered by the majority of professional opinion to be the proper load path. I want the wind load to flow from the cladding objects to the beams, and then from the beams to the columns. How can I manipulate the model to express this desired load path? Why can’t I mesh auto-cladding objects?

Using meshed shell objects instead of this auto-cladding elements would undoubtedly increase the computation time and complexity of the model. However, if I were to use regular shell objects, what settings in the shell object’s stiffness property modifiers would I have to change in order to observe the one way load path that I seek?

In addition, clicking on a beam element in post processing shows graphically that torsion in the beams is present in the model. However, the load tables from the Model Explorer tree show that torsion is not present. Is this a graphical bug?

 

[chekre]

Did u define point diaphragm ? If not this is normal that uget nothing.[highlight #FCE94F][/highlight]

 

[rbateman]

This just adds to my belief that the ETABS documentation is absolute crap.

No. Assigning a diaphragm property to a floor has NOTHING to do with applying wind to shells directly. It only matters if you assign it to a diaphragm.

Ashraf needs to stop spending millions on these stupid extravagant San Francisco parties and instead invest back in ETABS so we may get a complete reliable and robust program with a solid knowledge database and well written documentation.