DESIGN OF RAMP FOR EQ FORCES

Re: DESIGN OF RAMP FOR EQ FORCES

sureshprsharma — Sat, 15 Jan 2011 16:22:53 GMT

Sorry, the file was posted by Sri Chavda on Jan 10, not on Jan 11 as stated in my posting. The error may be noticed after opening the Staad Editor file.

Re: DESIGN OF RAMP FOR EQ FORCES

sureshprsharma — Fri, 14 Jan 2011 20:06:55 GMT

The last file sent by Sri Chavda sent on Jan 11 2011 shows error as under:

Line 481,482,497,498: Definition of Seismic load: selfweight is not to be factored with 1. Element weight has to come before floor weight. Hence the error.

Line 908,947,976,1005,1034,1052,1082,1199: The design parameter METHOD 0 has been repeatedly assigned to many members several times. The parameter is not supported by IS 456. Hence the error.

The error can be fixed by correcting the above inputs.

Re: DESIGN OF RAMP FOR EQ FORCES

SKLose — Tue, 11 Jan 2011 10:33:34 GMT

Himmatlal Chavda,

To the best of my knowledge, the MEMBER WEIGHT feature works quite well. When you provide the seismic weights under "DEFINE 1893 LOAD", you should use the syntax MEMBER WEIGHT, not MEMBER LOAD. If you typed the data using the editor, a mistake could have crept in unbeknownst to you. If you assign it using the graphical tools, the program generally does it without any errors.

In any case, attached is a model which shows the usage of that command.

If you are convinced that there is an error in the program, you ought to upload the model that reveals the error, or send it to the STAAD support people at Bentley.

Re: DESIGN OF RAMP FOR EQ FORCES

Himmatlal Chavda — Mon, 10 Jan 2011 10:38:48 GMT

Mr. sklose i have tried the said option of member load but it showed the error in generating the EQ forces. then i tried the plate load with plate load specification then the staad was able to generate the EQ forces.

Re: DESIGN OF RAMP FOR EQ FORCES

Himmatlal Chavda — Mon, 10 Jan 2011 10:17:07 GMT

this is the final model. verify it and say whether it is right or not.

Re: DESIGN OF RAMP FOR EQ FORCES

SKLose — Mon, 10 Jan 2011 08:33:41 GMT

I agree that selfweight has been omitted from the model he has attached. That and any other loads that have been omitted need to be included in the model.

Re: DESIGN OF RAMP FOR EQ FORCES

sureshprsharma — Sat, 08 Jan 2011 09:13:22 GMT

Thank you Mr. Lose for your valuable contribution and clarifying my doubts.

One more thing that I observe from the file posted by Mr. Chavada that he has not applied Live load or Dead Load on the inclined ramp. I suppose this has been inadvertently left. Please look into the file from your view and post your comments.

Re: DESIGN OF RAMP FOR EQ FORCES

SKLose — Sat, 08 Jan 2011 08:04:29 GMT

Don’t know why Mr.Sharma thinks that STAAD cannot generate earthquake forces on an inclined surface.

If the beam or slab is split up into several segments, the gravity load + the external weight acting on those segments or elements can be applied using the member load or element pressure load options, depending on the entity they are modeled as. Those loads will get converted internally during the analysis to lumped weights at the nodes of those entities. At each node where a weight gets lumped, a lateral load will be generated. You do not need floors in a structure in order for lateral loads to be generated.

Re: DESIGN OF RAMP FOR EQ FORCES

Kunal — Fri, 07 Jan 2011 12:35:59 GMT

I have uploaded the analysis file of the model.

Re: DESIGN OF RAMP FOR EQ FORCES

Kunal — Fri, 07 Jan 2011 12:26:33 GMT

Hi,

I run the model and found no error in output file. Program is calculating the seismic forces.

But, I did not cross check the values by manual calculation so if these are not maching. If there is such a case please report it to the support team of Bentley by generating a service ticket stating you problem and your Staad.Pro Version along with the build number. to generate the service ticket you should be in the SELECT Subscription Period.

Regards,

Kunal

Re: DESIGN OF RAMP FOR EQ FORCES

Himmatlal Chavda — Fri, 07 Jan 2011 10:26:16 GMT

here is the uploaded file

Re: DESIGN OF RAMP FOR EQ FORCES

Himmatlal Chavda — Fri, 07 Jan 2011 10:26:15 GMT

here is the uploaded file

Re: DESIGN OF RAMP FOR EQ FORCES

sureshprsharma — Fri, 07 Jan 2011 07:51:10 GMT

Mr. Chavada, what I understand that seismic load can not be generated for an inclined surface in Staad V8i. Most of the software what I understand have similar problem. It is necessary for Staad to generate EQ load that vertical axis must be perpendicular to the floor as per clause 5.31.2.5 of Technical Reference manual. The above stipulation is not satisfied in the extant model that you have described. The software is not able to locate a floor which is perpendicular to the vertical axis. Hence according to me it is not possible to generate error free EQ load.

Anybody who differs will be highly appreciated.

Re: DESIGN OF RAMP FOR EQ FORCES

sureshprsharma — Thu, 06 Jan 2011 18:22:51 GMT

I feel that for this type of structure all loads including self weight have to be converted into Joint Weght and applied to the joints to generate seismic load in the lateral direction. The usual format for loading may not work for inclined floor for generating EQ load in lateral direction.

Re: DESIGN OF RAMP FOR EQ FORCES

Kunal — Thu, 06 Jan 2011 16:10:49 GMT

Please Upload your file here. As far as this kind of model is concern one can define the Eq. Weights on the Structure and it works fine to generate the Seismic Forces..