Wood shear wall uplift load combinations
Wood shear wall uplift load combinations
(OP)
When we design hold downs for wood shear walls, we use the load combination (0.6-0.14SDS)D+0.7pE (seismic) and 0.6D+W (wind) to calculate the uplift. In an other word, the formula we use are T=(Mot-(0.64-0.14SDS)Mr)/L (seismic) and T=(Mot-0.6Mr)/L. We got many projects approved using these equations. In other people's spreadsheets, we found that they use safty factors instead of those ASCE load combinations. For example, in Daniel Li's spreadsheet, he uses safty factors 0.9 for seismic and 2/3 for wind. In an other word, he uses T=(Mot-Mr)/(0.9L) (seismic) and T=(Mot-Mr)/(2/3)/L. In his method, the dead load helps more to reduce the uplift tension. Does any one have any idea which method is right, or if you think neither is good, what do you use?
An other question is that in the book 2006 IBC STRUCTURAL/SEISMIC DESIGN MANUAL, the author uses the overstrength factor, omega, to evaluate the overturning moment. That results a gread tension value and is not practicable. We never use it and no plan checker questioned that so far. Any idea reguarding this issue? Any information will be appreciated.
Thank you very much.
An other question is that in the book 2006 IBC STRUCTURAL/SEISMIC DESIGN MANUAL, the author uses the overstrength factor, omega, to evaluate the overturning moment. That results a gread tension value and is not practicable. We never use it and no plan checker questioned that so far. Any idea reguarding this issue? Any information will be appreciated.
Thank you very much.





RE: Wood shear wall uplift load combinations
RE: Wood shear wall uplift load combinations
Mike McCann
MMC Engineering
RE: Wood shear wall uplift load combinations
Thank you.
RE: Wood shear wall uplift load combinations