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ENGCV512 Assignment
Part 1: Force Distributions for Flexible Diaphragm (30 points)
A four-storey hotel building is being constructed. The building has a design base shear of 1130 kN that
has been distributed as follows:
Level R: 450 kN
Level 4: 340 kN
Level 3: 225 kN
Level 2: 115 kN
All of the levels have the same wall layout and wall locations. At each level, all of the frames have the
same stiffness. The building mass can be assumed to be uniformly distributed.
Figure 1 Plan view of building
Figure 2 Elevation view of one
frame
1. Assuming the building has flexible diaphragms at each level, determine the force distribution to
each frame at every level of the building. Consider the forces as applied in the N-S direction
(vertical on the page).
Table 1 Forces on Frames, building with flexible diaphragms
Frame A B C D E F G H I
Level R
Level 4
Level 3
Level 2
Ground
Part 2: Force Distributions for Rigid Diaphragm (50 points)
2. For the same building, if the diaphragm is now rigid, determine the force distribution to each
frame at every level of the building.
3. Comment on the different force distributions for flexible and rigid diaphragms. Why is it
important to understand the diaphragm behaviour?
ENGCV512 Assignment 5
Table 2 Forces due to shear force, building with rigid diaphragm
Frame A B C D E F G H I
Level R
Level 4
Level 3
Level 2
Ground
Table 3 Forces due to inherent torsions, building with rigid diaphragm
Frame A B C D E F G H I
Level R
Level 4
Level 3
Level 2
Ground
Table 4 Total forces on frame, building with rigid diaphragm
Frame A B C D E F G H I
Level R
Level 4
Level 3
Level 2
Ground
ENGCV512 Assignment 5
Part 3 Diaphragm Forces – Flexible Diaphragms (20 points)
A one storey building has a flexible roof diaphragm. The building has two large holes removed to allow
for an indoor courtyard and roof access. The building has a base shear force of 450 kN.
4. For the building shown below, determine the diaphragm shear force. Draw the shear diagram
for the diaphragm. Compute the shear demand for the critical sections.
5. Determine the maximum chord force in the diaphragm.
6. If the diaphragm was rigid, explain how you think the shear and moment forces would change.