Week 11 Challenge

Modeling , Analysis & Design of Industrial building (PEB/Truss) in STAAD pro.

1. Purlin & Girts number determination problem

Calculate total number of purlins and girts required for the building with following inputs

Rafter span = 50 m

Bay spacing = 8 m

Roof slope = 1 in 10

Height of column = 12 m

Brick wall height = 2 m

Purlin spacing = 1.2 m

Girt spacing = 1.5 m

Solution:

Aim : A pipe carrying LNG rests on the shoe having vertical force of 125 kN. Friction load on the axis and friction force are required to be determined if there is TEFLON pad between shoe and pipe support.

Procedure :

Friction factor/Coefficient and friction load on piping:

Materials Friction Factor
Steel to Steel 0.3
Teflon to Steel 0.1

(A) When Steel pipe is resting on steel:


Friction force in longitudinal direction (Ff) = Coeff of friction x Gravity Load

= 0.3 x 125 KN = 37.5 KN

Friction load in transverse direction = 10% of piping operating load

= 0.l x 125 = 12.5 KN

(B) When Steel pipe is resting on Teflon :

Friction force in longitudinal direction (Ff) = Coefficient of friction x Gravity Load

= 0.l x 125 KN = 12.5 KN

Friction load in transverse direction = 10% of piping operating load

= 0.l x 125 = 12.5 KN

Result:

Friction load in longitudinal and Transverse direction are 37.5 KN & 12.5 KN respectively when pipe is resting on steel and these friction forces are 12.5 KN & 12.5 KN respectively when pipe is resting on Teflon.

2. Taper the beam according to BMD envelope

For the STAAD file attached. For given loading taper the beam for the BMD envelope and check utility ratio within limit. (Design Parameter is already applied)

Solution:

Aim: Identify the type of support such as Spring, Guyed, Stop or Semi Anchor ( Guyed+Rest+ Stop) or Rigid Strut from the given images.

Theory:

For the given cases:

1. Spring Support: Permit the pipe to move in vertical direction

2. Rigid Support: Allow small angular displacement and thermal movement.

3. Stop support: Restrained the movement of pipe in axial direction but allows the pipe movement in lateral direction

4. Semi Anchor Support: Restrict the pipes to move in axial as well as transverse direction.

5. Guid support: Restrained the lateral movement in two direction therefore also limits the rotational movemement of pipe but permitt axial movement of pipe.

6. Anchor Support: It does not permitt the pipe to move in any direction thus movement in all 6 degree of freedom is restricted.

Procedure:

For fig.1:

Type of support: Spring support

For fig.2

Type of support: Rigid support

For fig.3

Type of support: Stop support

For fig.4

Type of support: Semi Anchor support

For fig.5

For fig.6

Type of Support: Anchor Support.

Result: Types of Support for all the figures has been identified for the given cases.

3. Determining Wind load for certain category and condition as per IS 875 Part 3 :2015

An Industrial building of plan dimension 10m x 5m to be constructed (as in Figure below). Building is situated in Chennai. Find the wind pressure on the wall of the building. Assume wall opening as 15 %. Bay spacing = 2.5m.

Solution:

Aim: Model of pipe rack bent in oil plant is to be prepared from the given data and figures.

Given:

Height of Column = 9m

Height of First tier = 6m

Height of Second tier = 7.5m

Height of Third tier = 9m

Width of Pipe Rack = 7.5m

Span of each Bay = 6m

Number of bays = 7m

Top tier of pipe rack has 3 nos cable trays each 150 mm wide

Second tier of pipe rack has 4 pipes ,one of 24" diameter and one of 12" diameter, remaining two pipes are of dia 8"

First tier of pipe rack has 6 pipes ,one of 18 " diameter and remaining 5 pipes are of dia smaller than 8"

Elevation View:

Plan view:

Procedure:

1. Open a new Staad Flle.

2. Create the basic model of the Pipe Rack in Staad File.

3. We wil add the supports.

Now we will add the loadings on the Pipe Rack.

We need to add the following Loads :

1- Structural Dead Load :

• Load due to weight of Structure excluding weight of pipe i.e., Self Weight.

2-0perating Dead Load :

• Weight of pipe, fluid in it and insulation.
• UDL of 1.9 kN/m is asuumed for pipe of dia 8".
• Point load is considered at appropriate location for pipe larger than 8" dia pipes which will be reported by Piping Engineer.

3-Empty Dead Load :

• Weight of empty pipe without fluid in it but including insulation,it is assumed as 60% of operating load

4-Test Dead Load :

• In case test medium in pipe is not known, water with density of 1000 kg/m is considered as test medium so generally test load is same as operating dead load.

5- Cable Tray Load:

• UDL of 1 kN/m is considered.

All the above mentioned loads has been applied.

Various loads have been applied as shown below:

Structural dead load:

Operating Pipe Load for 8" diameter pipe:

Operating Pipe Load for 12" diameter pipe:

Operating Pipe Load for 18" diameter pipe:

Operating Pipe Load for 24" diameter pipe:

Empty pipe load:

Test pipe load:

Cable tray load:

Now, we will run the analysis to check the structure and rectify the error if any found.

Zero error has been found.

Result: The Given Pipe rack has been modelled in the Staad Pro, with the given Dimensions, Loading, Support and Specifications, also the analysis of the Pipe has been done successfully and Zero Error has been found.