Question

Solve the steel question - within 10 minutes

The maximum sidesway ( secondary) moments occur at the Select one: O a. column ends. O b. column midspan. c. beam midspan. O d. beam ends.

Answer 1

Basically in portal frames, the side sway is the algebric sum of the horizontal reactions due to the assumed sway moments must be equal to the sway force.

This sidesway will develop due to following reasons

1. When there is unsymmetrical loading is acting on the portal frames.

2. When different cross sections are present in a frame.

3. When different support are there for the columns given in a portal frame.

4. When there is settlement of support of the frame.

5. When horizontal loading present on the columns of the portal frames.

Now as per the question

The maximum sidesway moment will develop at column ends only.

In the beam the effect of yielding or settlement of supports was taken into account, but in portal frames sway will considered.

For a portal frame column, one end will have a support and other end will be a joint with beam.

At the joint of the beam the sidesway moment will be maximum.

Answer for the above question is a) column ends only.

b) as sway will be maximum at ends there will be sway at midspan but not Maximum. So this is not correct option

c) as sway moment will develop in columns of portal frames there is no chance of sway in beams. The beams of frames will translate only. So this option is not correct

d) same as option c reason.

So the correct answer for the maximum sidesway moment occurs at column ends only.