Project 1
Aim:
Q. A portal frame has following details:
Portal beam having length of 4m and cross section of 300mm x 600mm (depth) and portal columns have height of 3m and cross section 300mm x 300mm.
1. The portal beam has two Bearing locations 1m from either end. The load from each bearing is 75 kN. Calculate the support reactions and displacement of each node.
2. Now change both the supports to fixed and compare the reactions and displacements with that of previous sub question.
3. Now provide 3 support conditions with 50 kN such that total load on the frame is same as that of Point 1. The bearings are 1m apart and 1st bearing is 1m from the end. Compare the reactions with that of sub question 2 and comment on the results.
4. Change the cross section of column to 300 x 400 mm such that 300mm width of column aligns with 300mm width of Portal beam. Rest all conditions remain same as that of sub question 2. Compare the portal beam and columns bending moment with that of sub question 2.
5. Now change the orientation of column such that 400mm size aligns with 300mm width of Portal beam. Compare the beam and column results with that of Sub question 4. Comment on the results.
Aim and Introduction:-
- The aim of this challenge is to determine the forces, Bending moment and shear forces acting on the structure with different types of support and different load conditions using Staad Pro.
- So first of all the model will be created in Staad pro. as per given data with given loads applied on the the structure.
- Then create as per different support conditions with different orientation. The reactions, stresses and bending moments due to the loading is being analyzed for diffrent structures and comparing the results with each other.
Portal beam having length of 4m and cross section of 300mm x 600mm (depth) and portal columns have height of 3m and cross section 300mm x 300mm.
Staad Model
Creating the Project
- The portal beam has been created as given with 4m length.
- The columns are also created as given with 3m height.
1. The portal beam has two Bearing locations 1m from either end. The load from each bearing is 75 kN. Calculate the support reactions and displacement of each node.
- Two bearing locations have been created.
- Property for the beam was defined and assigned to the beam.
- Property for the columns was also defined and assigned to the columns of the structure.
- The 3D view of the portal frame is shown below:
- Support Condition
- Pinned support and roller support have been defined and assigned to either base nodes.
- Loads and Definitions
- Dead load defined and was assigned to the whole structure.
- Superstructure load as nodal load through the bearing was defined and applied to the structure.
- The structure was analyzed and the output gave the result as 0 error.
Result
- Displacement
- Support Reaction
2. Now change both the supports to fixed and compare the reactions and displacements with that of previous sub question.
- In this case the support conditions were changed to fixed support on both nodes.
- The structure was analyzed and the output gave the result as 0 error.
-
Result
- Displacement
- For the maximum load case
- Support Reaction
3. Now provide 3 support conditions with 50 kN such that total load on the frame is same as that of Point 1. The bearings are 1m apart and 1st bearing is 1m from the end. Compare the reactions with that of sub question 2 and comment on the results.
- Created the third support node from the super structure in the mid section of the beam.
- 3 support conditions for bearing was created and 50 KN was applied to the structure.
- The structure was analyzed and the output gave the result as 0 error.
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Result
- Displacement
- For the maximum load case
- Support Reaction
- In this case, after comparing to Case 2 , the displacement in the mid point was found to be higher in this case (Case 3).
- But as the super structure loading is symmetrical in both the case and the magnitude is same, so the vertical reaction (Y =75 kN) in both the cases are the same.
4. Change the cross section of column to 300 x 400 mm such that 300mm width of column aligns with 300mm width of Portal beam. Rest all conditions remain same as that of sub question 2. Compare the portal beam and columns bending moment with that of sub question 2.
- The cross section of the column was changed to 300 x 400 mm in the model with reference to Case 2.
- The property in model was be changed.
- The 3D view of the structure after aligning the 300mm width of column section to the 300mm of the beam section is shown below:
- All other sections,loadings & support conditions remained the same.
- The structure was analyzed and the output gave the result as 0 error.
Result and Comparision
- The Bending Moment Diagram with Maximum Magnitude and Magnitude at Mid Point and Ends for the model created in Case 4 is shown below:
- The Bending Moment Diagram with Maximum Magnitude and Magnitude at Mid Point and Ends for the model created in Case 2 is shown below:
From the above two results,it can be concluded that the Bending Moment at the Mid Section of the Beam is more in the Case 2 as compared to the Case 4.
The bending moment in the mid section of the beam is lesser in Case 4 but end moments is higher as the section (YD) in this Case was increased.
5. Now change the orientation of column such that 400mm size aligns with 300mm width of Portal beam. Compare the beam and column results with that of Sub question 4. Comment on the results.
- The cross section of the column was changed to 400 x 300 mm from 300 x 400mm in the model with reference to Case 4.
- The property in model was changed accordingly.
- The 3D view of the structure upon aligning the 400mm width of column section to the 300mm of the beam section is shown below:
- All other sections, loadings, & support conditions remained the same.
- The structure was analyzed and the output gave the result as 0 error.
Result and Comparision
- The Bending Moment Diagram with Maximum Magnitude and Magnitude at Mid Point and Ends for the model created in Case 4 is shown below:
- The Bending Moment Diagram with Maximum Magnitude and Magnitude at Mid Point and Ends for the model created in Case 5 is shown below:
- The Bending Moment in the Mid Section of the Beam is higher and the Bending Moment in end section in Case 5 is lesser as compared to Case 4. This is because the section modulus in the respective 400mm dimension direction is higher than the other direction.
- Shear Force
- The shear force with Maximum Magnitude and Magnitude at Ends for the model created in Case 4 is shown below:
- The shear force with Maximum Magnitude and Magnitude at Ends for the model created in Case 5 is shown below:
The Maximum Shear in the columns in greater in Case 4 as compared to Case 5 which is due to the change in width of the column.
Axial Force
- The Axial Force for the model created in Case 4 is shown below:
- The Axial Force for the model created in Case 5 is shown below:
In this comparision, axial force in the Beam in Case 4 is greater as compared to Case 5 which is due to the change in width of the column.