Hi Bentley Team,
I made a pushover, and at the 'Define Solution Control' window, I marked the option: 'Push upto defined displacement at Control Joint'
Besides, at the 'Define Load pattern' window, I didn´t mark any load pattern but just the options 'Direction' and 'Number of Push load steps'
So, the Total Base Shear appears as Zero in that window.
My structure has only lumped masses at the nodes (no rigid diaphragm)
Now, my questions are:
In such a case, what exactly does Staad-pushover?
Does it apply an increasing acceleration to all the lumped masses till the target displacement is reached?
Does it apply increasing displacements at the control joint?
Apart from all that, I need to make a graph of the Capacity Spectrum (notice, I am not talking about the capacity curve)
Does the Staad bring the Capacity-Spectrum data table as a separate output-file, or can be included by any means in the .ANL file?
If the answer is no, then:
Does it brings the Capacity Curve data (table) as a separate output-file that I could read from Excel by using Visual basic?
Indeed, I desperately need to automate the reading of the Capacity-curve data table or Capacity-Spectrum data table,
so any help on this matter will be deeply appreciated.
Please, kindly notice that I know how to easily copy/paste such data, but that is not of my interest, I need to automate the data reading.
I don't understand why Staadpro didn't included all the dynamic output in the OPENSTAAD commands, I deeply regret that.
Anyway, many thanks in advance for any help on this matter, and many thanks for all the other questions the Staad Team have
always kindly and promptly answered!
Best regards
Your question : … In such a case, what exactly does Staad-pushover?
Response : When no push load pattern is selected and also total base shear to be distributed is Zero, the program does the following:
1. It considers 10% of gravity loading to be distributed as lateral load which acts as total base shear to be distributed (Section 4.3.2).
Following warning message is issued
2. The base shear, thus calculated, is distributed along the height of the structure using default method termed as “Method 3” (Sections 1.8 and 4.3.1). This acts as push load on the structure.
Your question : Does it apply an increasing acceleration to all the lumped masses till the target displacement is reached? Does it apply increasing displacements at the control joint?
Response : The total Push load pattern (as calculated by the program using default method 3) is divided by the “Number of Push load steps” to get the incremental push load. The first pushover load is the gravity load applied on the structure. The first incremental lateral push load case starts from the end of gravity load case, the second lateral load case starts from the end of first lateral push load and so on until the target displacement is exceeded. (Section 5.1.3)
Your question : … Apart from all that, I need to make a graph of the Capacity Spectrum (notice, I am not talking about the capacity curve). Does the Staad bring the Capacity-Spectrum data table as a separate output-file, or can be included by any means in the .ANL file?
Response : The analysis engine converts Capacity Curve to Capacity Spectrum curve if only “Method 2” is used for generating pushover loading pattern. Method 2 uses a vertical distribution proportional to the shape of the fundamental mode in the direction under consideration (Section 1.8.2). There is an unpublished STAAD command “TXT 1”. If this is defined as input under “DEFINE PUSHOVER DATA” the analysis engine will generate series of external text files and one of these would be the …PUSH_CAPACITY_SPECTRUM.TXT. You can refer to this file for the Capacity spectrum. This file would be created in the same model folder.
Please note that “TXT 1” is an unpublished STAAD command. As such STAADPro user interface ( UI ) will not recognize it. However you can ignore UI error message. Analysis engine will recognize this command.
Your question : ...If the answer is no, then:Does it brings the Capacity Curve data (table) as a separate output-file that I could read from Excel by using Visual basic?
Response : Under Post-processing -> Pushover -> Capacity Curve, you will get Capacity Curve data table. A text file … PUSH_CAPACITY_CURVE.TXT created in the same folder as the model will also contain the capacity curve data. However there is no OpenSTAAD function corresponding to this functionality.