What kind of hand checks should we perform before the detail analysis and design of a steel structure? What should we check briefly so as to be sure that no major mistake happens by the use of the software?

Regards

F.

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• Grunf, Grunf
Compute the column reaction by area method roughly and compare it to your analysis result, should be almost the same.

The major checks we used to apply are:

1) Tributary area calculation and comparing it with analysis result,

2) checking and matching the base shears, scaling factor should not be less than 1,

3) arbitrary checking moments for the beams,

4) I am using Staad pro, so model should be checked thorughly and moments should be released secomdary beams.

Regards

Before starting 3D model in Etabs or any software I perform following task as my preliminary design and atleast to give preliminary structure depth and size to Architect in meetings.

1. I have created simple load takedown spreadsheet. Which considers tributary area and uniform load load on each level to calculate reaction at base. That will also help to quickly size interior and exterior column and foundation for talking and comparing purpose.

2. Calculate quickly total wind exposure area * wind load = total base shear

3. For floor framing use basic thumb rules like if beam span is 34 ft, for composite floor system the beam depth would be atleast half of it (34/2 = 17). Therefore most likely W18 sections (For US codes).

4. Sometimes I also quickly model my lateral system (Brace or moment frames) in one single line attached to each other with rigid link in RISA to get the preliminary sizes of braces. My observation indicates that generally the final design is within 10 to 15% difference.

Please share your thoughts and ideas. That will help everyone to improve the engineering steps and quality of work both.

07-30-2009, 11:23 AM
(This post was last modified: 07-30-2009, 11:26 AM by iceman84. *Edit Reason: *)
Checks are one thing, predimensioning is another thing.

Predimensioning can be based on different criteria like strength, stifness or ductility.

In my opinion checks should be made after finishing the analysis (checks for equilbrium of the node, check for base shear, check for tributary area, etc.). Another check is that of the modes of vibration (eigenperiods, eigenshapes, mass participation factors) and compare the results from the analysis with the results obtained using a simplified method (like Rayleigh). The eigenperiods should be compared with the values obtained using the simplified formulas.

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Is there any book about the simplified Rayleigh method?

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i want to know, how we calculate length of shear wall required for a building? what formulas involved? im using British Standard. Thank you

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