Modeling water pressure in SAP2000 – Tuotorial


Google Drive: A Quick Design Tool

Since now a days everyone is using smart phones therefore it always attracts me to do something creative for field of structural engineering. Lots of time to I thought about writing an App but for that I need to learn the programming language, and time is the biggest hurdle for that. Also there are few apps which are available for Apple IPhone and Android Phones, but all of them are charging almost $10 and most of them are not very good.

So here is what I suggest; Install Google Drive on your smart phone and create a spreadsheet with simple formulas, keep it in “Design Help” folder and use it when needed for quick check.

One thing which I would like to mention is that Google drive files can be accessed offline. So in case you don’t have wireless connection or limited data package, the google drive files can still be accessed.

Comments if you have any other suggestion!!!!

If you are interested in downloading the spreadsheet then check out the following link:

Google Drive Main

Google Drive Photo 2


SAP2000-Accidental Torsion in Response-Spectrum Case

NOTE: This discussion applies only to SAP2000. ETABS automatically includes the accidental eccentricity specified in the response-spectrum load case.

To consider accidental torsion in a response-spectrum case, eccentricity should be added as a separate static load case. The response-spectrum (SPEC) and eccentric (ECC) load cases should then be combined as SPEC + ECC and SPEC – ECC load combinations. Each level should have a rigid diaphragm, otherwise accidental eccentricity is not of significance.

Accidental torsion is applied through the following process:

  • Define a load case named ECC (or other) of Type = Quake, Self-weight multiplier = 0, and Auto = None.
  • Select any point on the diaphragm at each level.
  • Select Assign > Joint/Point Loads > Force > Moment Global ZZ, then specify the appropriate value for torsional moment.
  • Evaluate SPEC + ECC and SPEC – ECC load combinations. Note that the software already considers SPEC in both directions.

Accidental torsion may be considered without rigid diaphragms, though loading should be more distributed. Torsional moment is calculated at joint locations within a flexible diaphragm by first resolving the total lateral force in a given direction at each story level. This is done by summing the auto-seismic loads applied to joints within each story level. This force is then multiplied by the eccentricity to generate torsional moment (T). This torsion is then distributed to all joints at the story level in proportion to the joint mass as follows:

  • Torsion at a given joint at a story level = T * (Mass at the joint / Total mass of all joints at the story level)

It may be convenient to use an Excel spreadsheet to calculate torsion at joint locations. Using interactive database editing, data may then be entered into SAP2000