6. A proposed 5-story health care facility with 110 people maximum occupancy is
ID: 2311657 • Letter: 6
Question
6. A proposed 5-story health care facility with 110 people maximum occupancy is to be constructed in Southbend, Indiana. The ground motion periods are expected to be short at this location. The soil report indicates that the soil at the construction site is very dense silty-clay with soft rock profile. Use the same building dimensions and floor weights as in problem 5. Use the IBC 2003 Code to calculate: A. The design base shear. B. The respective vertical distribution of base shear at each floor.Explanation / Answer
Solution:-
Base shear(VB ) = Ah *W
W = weight of building
Building weight is not given.
Let floor weight =250 kips
And roof weight = 100 kips
Ah = Z/2 *I/R * Sa/g
Z= 0.36 (for Indiana)
I =1.5 (for medical building)
R = 3
Time period (T) = 0.075*(h)0.75
= 0.075*(20.1168)0.75 = 0.71 second
h = 20.1168 meter (building height)
For Medium soil sites
Sa/g = 1.36/T = 1.36/0.71 = 1.91
Ah = 0.36/2 * 1.5/3 * 1.91 =0.1719
Total weight of building = 4*250 +100 = 1100 kips
VB = Ah*W
Design base shear(VB)= 0.1719 *1100 = 189.09 kips Answer
Distribution of base shear on each floor
For first floor(Q1) = VB *W1 h12/(W1h12 +W2h22 + W3h32 +W4h42 +W5h52)
Q1 = 189.09 * 250 * 142/(250*142 + 250 *282 +250 * 412 +250 *542 + 100 *662 )
= 5.06 kips Answer
For second floor (Q2) =189.09 *250 *282/(1.82985 *106)
= 20.25 kips
For third floor (Q3 ) = 189.09 * 250 *412/(1.82985 * 106)
= 43.427 kips
For fourth floor (Q4) = 189.09 *250 *542/(1.82985*106)
= 75.33 kips
For roof
Q5 = 189.09 *100 *662/(1.82985 *106)
= 45.01 kips Answer
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