Week 9 Challenge

1. Design of dual slope (pitched) roof frame

Design a 3 hinged pitched roof frame of a steel building. Assume no wind load acting on the walls and roof. Analyse the frame structure and draw bending moment, shear force and axial force diagrams of the frame. The slope of the roof is 1 in 10 and the roof is accessible for maintenance purpose (assume 75 kg/m²) only. Dead load on the roof are given below. Assume bay spacing as 5 m and frame width is 20 m. (Design code as per AISC:ASD. No seismic load consideration required)

Weight of roofing sheet = 5kg/m²

Weight of purlins + tertiary members = 25 kg/m²

Roof Slope 1:10

tan `theta`= (1/10)

`theta` = 5.71 degrees

Bay Spacing = 5 m

Live Load = 75 kg/m² = 0.735 kN/m² = 0.735 x 5 = 3.675 kN/m

Dead Load = 5 kg/m² + 25 kg/m² = 30 kg/m² = 0.294 kN/m² = 0.294 x 5 = 1.47 kN/m

Procedure:-

Open the STAAD Pro Software and create a new model as shown below.

Create the first node at (0,0,0)

^{Create the second node at (10,(tan 5.71 * 10), 0) = (10 , 1 , 0)}

Create one more node at (0,-5,0) assuming the height of the column as 5m

Now add 2 more points and add beams to complete the frame

• Define Section properties in the Properties Tab.

Then assign Sections to the members.

• Now create and assign the Pinned support

• Add Dead Load, Live Load and Load Combination to the members.

Now assign the DL and LL as shown

Now lets start the analysis. Analysis and Design - Define Commands - Perform Analysis

Now go to Post processing

Select the loading as load combination from the left most Load tab. Right click on the table and select Results set up to view the results of combination load case

Mz- BMD:

^{Fy - SFD:}

^{Fx - AFD:}

2. Draw Bending Moment diagram for following Frame using STAAD.Pro

Figure 1)

Procedure:

Create nodes as shown

Add beams to complete the frame

Assign the properties to the members as shown

Now add supports to the nodes as shown

Add loading - DL, LL , Load combinations

Now lets assign the DL to the members

LL and load combinations could be deleted

Now lets run the analysis

Go to Post processing

Mz - BMD:

Fy - SFD:

Fx - AFD:

Figure 2)

Procedure:

Create nodes as shown below

Second node: (10,(tan 20 * 10),0)=(10, 3.639,0)

Add beams to connect the nodes

Then assign member properties as shown

Assign supports as shown

Add the load cases as shown

Now analyse the beam and view the results under Post processing

BMD:

SFD:

AFD:

Figure 3)

Procedure:

Create nodes and beams as shown

Assign materials as shown

Add supports to the nodes

It could be noticed from the question that the beam has an internal hinge

Go to Specifications - Beam

Now add the loadings as shown

BMD:

Analyse the structure

SFD:

AFD:

3. Deflection of a frame, present result from STAAD.Pro

Procedure:

1. Determine the lateral deflection at point A & Vertical deflection at mid section of beam between B & C from Figure 1 in previous challenge.

The lateral deflection at point A = 0.090 mm

Vertical deflection at mid section of beam between B & C = 27.846 mm

2. Determine the lateral deflection at point A & Vertical deflection at mid section of beam between A & B from Figure 2 in previous challenge.

Max lateral deflection at point A = 1560mm

At midspan = 1580mm

3. Determine the lateral deflection at point A & point B from Figure 3 in previous challenge.

Max lateral deflection at A = 0 mm

Max lateral deflection at B = 74.488 mm