07-30-2009, 03:01 AM
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.
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.