APPROACH TO THE ISSUE
The focus is to analyze a light wood
frame home in a hurricane prone
region in the United States. The choosen region is the gulf Coast
region and the Atlantic Coast region. Two main force system are looked
at; Wind Pressure and Water Pressure. I analyze the main lateral
resistance system's ability to resist these two forces. The main
lateral resistance is in the floor diaphragms and shear walls.
CASE 1: WIND FORCES ONLY
The first case that was analyzed was
the wind only case. The real
life application for this case depicts a home that is located far from
the coast but still experiences strong winds from the hurricane. The
Saffir-Simpson Hurricane Scale is used for the wind speeds in miles per
hour. ASCE 7-05 is used to relate wind speed produced by the hurricane
into a pressure that acts directly on the face of the house. Section 6
of ASCE 7-05 deals with Wind Loads on structures. The loads computed
are particularly applicable to the residents living in this area and
special design considerations should still be considered even though
they are outside of the storm surge path.
The wind pressure is resisted by the
wood diaphragms and transfered
into the top wood chords before being transfered into the wood shear
walls. Per the ASCE code, the wind pressure can be taken as uniform
over the height of the house. The choosen house is designed with shear
walls located only on the side walls, totalling two shear walls. The
diaphragms are located at z=10 ft (ceiling of the first floor) and at
z=0 ft (ground floor). Tributary areas are used to distribute the
pressures between the two diaphragms. Upon calculating the force in the
diaphragm and the shear wall; a sheathing grade and nailing schedule is
choosen to adequately resist this force.
CASE 2: WIND AND WATER PRESSURE
The second case that was analyzed is the combination of wind and water acting upon the structure. The real life application for this case depicts a home located right on the coast. These homes are generally considered to be worth a considerable amount. Residents should be aware of the safety of the home they reside in and whether that structure can resist both wind and the water loads that it would face for different hurricane categories. The Saffir-Sampson Hurricane scale is used for the surge height in feet. Fluid Mechanics is used to compute the hydro-static force acting upon the house at the surge height given by the Saffir-Sampson Hurricane scale.
The same method is used to choose the
diaphragm and shear wall
sheathing grade and nailing schedule as that for the singular wind case.
From the forces it is determined if a
sheathing grade and
nailing schedule is available to resist the forces for both cases.