A 5 Story essential facility is to be built in the state of

A 5 Story essential facility is to be built in the state of Ohio. The building footprint area is 180 ft long by 80 ft wide. The proposed structural system is ordinary steel braced frame. The weight of each Floor is 250 Kips and the roof is 100 kips. See the sketch below for floor heights. The soil report indicates that the building is constructed on stiff clay.

A. Calculate the design base shear based on the UBC code.

5. A 5 Story essential facility is to be built in the state of Ohio. The building footprint area is 180 ft long by 80 ft wide. The proposed structural system is ordinary steel braced frame. The weight of each Floor is 250 Kips and the roof is 100 kips. See the sketch below for floor heights. The soil report indicates that the building is constructed on stiff clay. A. Calculate the design base shear based on the UBC code. B. Calculate the respective vertical distribution of base shear at each floor. 12.0 ft 13.0 ft 13.0 ft 14.0 ft 14.0 ft Base Shear 80.0 ft

Solution

Solution:-

Given

Each floor weight =250 kips

Roof weight = 100 kips

Design seismic base shear :-

V_B = A_h*W

Design horizontal seismic coefficient:-

A_h = Z/2*I/R *S_a/g

Z = 0.36

I = 1

R = 4

Natural period (T) = 0.085 (h)^0.75

                                 = 0.85 * (20.12)^0.75 = 0.807 second

Where h is in meter

S_a/g = 1/T = 1/0.807 = 1.23

A_h = 0.36/2 *1/4*1.23

      = 0.055

Design base shear(V_B) = 0.055 * (250*4 +100)

                                         = 60.5 kips     Answer

Distribution of design force:-

Design lateral force at first floor

Q₁ = V_B *W₁h₁²/(W₁h₁² +W₂h₂² +W₃h₃² + W₄h₄² + W₅h₅²)

     = 60.5 * 250*14²/(250*14² + 250 *28² + 250 * 41² + 250*54² + 100 * 66²)

     = 60.5 * 49000/(1.82985*10⁶ )

   = 1.62 kips

At second floor

Q₂ = 60.5 *250*28²/(1.82985 *10⁶)

      = 6.48 kips

At third floor

Q₃ =60.5 * 250 * 41²/(1.82985*10⁶)

     = 13.89 kips

At fourth floor

Q₄ = 60.5*250*54²/(1.82985 *10⁶)

     = 24.1 kips

At roof

Q₅ = 60.5 * 100 *66²/(1.82985 *10⁶)

    = 14.4 kips   Answer