1 A5 Story residential building is to be constructed in a su

1. A5 Story residential building is to be constructed in a suburban community in southeast Michigan. The building is to be located on a flat terrain with dimensions of 180 ft in length by 80 ft in width. The floor heights are shown in the Figure below. Find the wind load on the building diaphragms using UBC code. Roof parapet height-5.0ft Wind Direction 5th Floor height-12.0ft 4th Floor height-13.0ft 3rd Floor height-13.0ft 2nd Floor height-14.0ft 1st Floor height-14.0ft 80.0 ft

Solution

in ubc code 97 the formula for calculating wind load is

F= AXP  

WHERE

F= WIND LOAD

A= PROJECTED AREA

P= WIND PRESSURE

here

A = hight of building x length of building

= 71 x 180

now calculating P

P= Ce x Cd x Qs x Lw

where

Ce is the combined height, exposure and gust response factor,

Cq is a pressure coefficient (it is equivalent to the drag coefficient in the previous two equations),

Qs is wind stagnation pressure, and

Iw is importance factor

Ce can be determined by UBC 97 Table 16-G

for flat terrain exposere C can be applied

for hight 72 the value of Ce is 1.43

Now Cd

for flat plate such as face of building Cd is 2

Now Qs

Qs = 0.00256 x V²

where V is the speed of the wind in miles per hour (mph)

Michigan is situated in Zone A where average wind speed is 86.6 mph

so, Qs = 0.00256 x 86.6² = 19.2

Now Lw

Calculations for buildings with standard use have an importance factor of one

so the total wind load is

A X P

71 X 180 X 1.43 X 2 X 19.2 X 1 = 701775.36 lbs