braced roof

huangyhg

braced roof
i would like to know say for example a portal frame on its north side is braced in the roof in its second last bay and consists of mullions and rafters in its last bay, how the wind loads from the north are transferred to the bracing in the roof (eg there are struts on the east and west wall is the wind transferred thru the struts to the roof bracing??) why would an engineer locate the roof bracing one bay in from the end and not on the last bay in this situation? cheers..  
if there are no struts along the length of the wall then the purlins may have been designed to transfer the load.
as per the bracing in the second bay, this same question has  been asked ina recent post.
csd