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ibc simplified wind load application
the ibc simplified wind load provisions (1609.6) states that the horizontal pressures represent the total of the windward and leeward net pressures. how do you determine which portion of this total is to be applied to the windward surfaces and which to the leeward? for example on a spandrel beam, would you apply the entire load on one side of the building or would it be a portion of the total?
in table 1609.6.2.1(1)is the basic wind speed supposed to be the 3-second wind gust speed or the fastest mile wind speed? (i was wondering because table 1609.3.1 establishes a conversion between the two).
if you are designing a spandrel beam, you wouldn't use the main wind force wind loads but rather the components and cladding wind loads. the simplified provisions (i think) are mwfrs wind.
thanks for the reply. i still would like to know if there is a way to apportion the leeward and windward parts of the load to the mwfrs. in the old sbc and even in asce 7, section 6, the windward and leeward apportionment is addressed(usually .8 x windward and .5 x leeward of a certain basic wind pressure), but since we are given the total in ibc i thought it would be something like .8/1.3 for windward and .5/1.3 for leeward (61.5% and 38.5% respectively). i just didn't see anything in the code.
i don't think their is a straight answer to your question. most of the time i use the analytical procedure because my buildings are not simple. what i do know is that generally when the simple procedures are used then their is generally simplified analysis to go with it. thus the wall load is generally loaded onto the windward column or even resolved into a point load at the eave for analysis. for individual components you can use table 1609.6.2 (components and cladding). this table gives you positive and negative pressures to design with. the wind loads are based on 3 second gust. the conversion table is so that you can convert to fastest mile if required. |
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