Outtrigger belt truss system

7/31/2019 Outtrigger belt truss system

1/7

Assignment No. 6 Continuous Medium Method

Afzal Waseem 1

Assignment No. 6 ContentsProblem No. 1 ............................................................................................................................................... 2

At Top of the Building: .............................................................................................................................. 2

Moment: ............................................................................................................................................... 2

Drift at L: ............................................................................................................................................... 3

At mid height of the Building: ................................................................................................................... 3

Moment ................................................................................................................................................ 3

Drift at L/2 ............................................................................................................................................. 3

Problem No. 2 ............................................................................................................................................... 4

Data: .......................................................................................................................................................... 4

Calculate: .................................................................................................................................................. 4

Moment of Inertia of Core (I).................................................................................................................... 4

Parameter S is a function of flexural rigidities of the core: ...................................................................... 4

Parameter S1 is a function of flexural rigidities of the column: ................................................................ 5

Aplha (): .................................................................................................................................................. 5

Beta ():..................................................................................................................................................... 5

Factor B: .................................................................................................................................................... 5

Factor C: .................................................................................................................................................... 6

(T) Axial Force in any column at Height x: ................................................................................................ 6

1. The horizontal drift at the top of the building ...................................................................................... 6

2. The base moment ................................................................................................................................. 7

3. Calculate the efficiency of the outrigger system based on top drift and base moment ...................... 7


2/7


Afzal Waseem 2

Assignment 6: Design problem- Out-rigger belt truss system

Problem No. 1

60-story single out-riggerred building system with a total height L = 240 m (@ 4 m story height)

as shown in the Figure.

The following data are given:

E = modulus of elasticity = 200GPa

I = moment of inertia of the core = 400 m4

A = area of the perimeter columns = 120000mm2

= 0.12 m2

d = distance out-to-out of columns = 40 m

W = intensity of the wind load per unit height of the structure = 45kN/m

Calculate the drift at the top and moment induced at the outrigger

location for out-rigger location at the top and mid height of the building

At Top of the Building:

Moment:

W = 45kN/m

L = 240 m

E = 200GPa = kPaI = 400 m

4


3/7


Afzal Waseem 3

Drift at L:

At mid height of the Building:

Moment

Drift at L/2


4/7


Afzal Waseem 4

Assignment 6: Design Problem (use continuous medium method)

Problem No. 215-story central core outrigger building with a story height of 12 ft

and having 3 outriggers. Building subjected to a uniform lateralload w of 0.7 kip/ft

Data:

Height (H) = 15 x 12 = 180 ft

Distance between the perimeter columns d =70 ft

Core wall: E= 30000 ksf, width a = 30 ft, thickness, tw = 1ft

Outrigger: Eo = 30000 ksf; Io = 4ft4

Perimeter column: Ec = 30000 ksf; Ac = 30ft2

Calculate:

(1) The horizontal drift at the top of the building

(2) The base moment

(3) Calculate the efficiency of the outrigger system based on top drift and base moment

Moment of Inertia of Core (I)

Parameter S is a function of flexural rigidities of the core:


5/7


Afzal Waseem 5

Parameter S1 is a function of flexural rigidities of the column:

Aplha ():

Beta ():

Factor B:


6/7


Afzal Waseem 6

Factor C:

(T) Axial Force in any column at Height x:

1. The horizontal drift at the top of the building


7/7


Afzal Waseem 7

2. The base moment

()

3. Calculate the efficiency of the outrigger system based on top driftand base moment

The second terms in Eqs. 5 and 6 represent the relative reductions in the drift and base

moment that result from the outrigger bracing and, thus form a measure of the efficiency of

the bracing.

Documents

Outtrigger belt truss system