11-12-2009, 04:32 PM
hi
for very special cases that could be done for simple and symetric buildings for ex.,,, but what is essencial for a good structural response for dynamic loading like wind an eartquake, because that what´s we are talking , you sould provide equal stiffness and resistance in both "directions" ( cotes are used because in some structures it's nor easy do define two ortogonal directions). This can be achieved by providing a structural sistem where the center os mass of the floors are coincident ( well that is almosts impossibele to the simplifications in the whole process versus the as built building ) with the center of rigidity. This avoids torsional problems and you have a structural scheme that is more simple to understand and wich response is more predictable. Remenber the structures behave like their were build and not like they apear in fancy structural software. So 1) predesign for gravity+live loads with or not considering in this early stage lateral loads . 2 ) minimum of 3 bays for direction ti achieve minumum redundancie 3) if bays length are similar in both directions as a rule of thumb think only in terms of section enertia to be similar in bothe directions. 4 ) built your model in ETABS or SAP or other and refin the design to achive the closest possibel center of mass to center of rigidity.
This explanaton was very simplifyed but i hope it could contibute for something.
best regards
for very special cases that could be done for simple and symetric buildings for ex.,,, but what is essencial for a good structural response for dynamic loading like wind an eartquake, because that what´s we are talking , you sould provide equal stiffness and resistance in both "directions" ( cotes are used because in some structures it's nor easy do define two ortogonal directions). This can be achieved by providing a structural sistem where the center os mass of the floors are coincident ( well that is almosts impossibele to the simplifications in the whole process versus the as built building ) with the center of rigidity. This avoids torsional problems and you have a structural scheme that is more simple to understand and wich response is more predictable. Remenber the structures behave like their were build and not like they apear in fancy structural software. So 1) predesign for gravity+live loads with or not considering in this early stage lateral loads . 2 ) minimum of 3 bays for direction ti achieve minumum redundancie 3) if bays length are similar in both directions as a rule of thumb think only in terms of section enertia to be similar in bothe directions. 4 ) built your model in ETABS or SAP or other and refin the design to achive the closest possibel center of mass to center of rigidity.
This explanaton was very simplifyed but i hope it could contibute for something.
best regards