distribution of shear forces in four story building

[calculor]

I am a recent graduate that has been given the task to design a four story timber frame building. The building consists of two wings that are at an angle of 140 deg. It has an elevator shaft that extends from the underground parking garage to the fourth floor.It also has a fire separation wall that also extends from the first floor to the fourth floor. The fire wall is approximately 5 feet from the edge of the elevator shaft. the length of each wing is approximately 219 feet. Wind load always governs in this part of the country (eastern Canada), wind load is 30psf.How do you locate the centre of resistance (CR) for this shape building? Should I project the lengths of each wing vertically and consider the building as a rectangular building or should I consider each wing to be an individual building and locate the CR for each wing? If the shaft and fire wall do not provide enough shear resistance I will have to use some of the timber walls. I assume I would have to calculate the stiffness of each element (concrete, masonary wall, and wooden wall), k=EI=EtL^3/12 and distribute the load according to the stiffness of each element.Any help would certainly be appreciated. P.S. I know, I know, this is way too long.

 

[Trussdoc]

I don't think you can make a 219 foot wing work in timber without an interior shear wall; hopefully, you will have a few walls that line up top to bottom within that space.

 

[Bannu]

calculor,

I think you need to separate two wings structurally analyse for wind forces separately for better lateral resistace.You may definitely need to help with additional shear walls.

Of course the latter procedure is well known, find out the relative stiffness of the walls and distribute the lateral loads. UBC 97 requires to do rigid diaphram analysis which not very practical for wood framed structures, whoose behaviour is more like a flexible diaphram.

So, you may employ the envelope method i.e. analyse by both flexible and rigid diaphram methods and take the worst wall forcesf for your design.