Frames — exercises | Queensferry

Module 7Level 3change

Fix the bases of a swaying portal

A pinned-base portal frame sways under a horizontal load. Its bases are then changed to fully fixed. What happens to the sway?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The frame sways much less, and the columns bend in double curvature with an inflection point partway up.Option B

The sway is unchanged, because the load is the same.Option C

The frame sways even more, because fixing the bases adds load.

Module 7Level 3bending moment

Do the columns bend under gravity load?

A portal frame carries a uniform gravity load on its beam only. Which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The beam sags between hogging knees, and the columns also carry bending moment — the rigid joints transfer it around the corners.Option B

Only the beam bends; the columns carry pure axial force with no moment at all.Option C

The beam hogs in the middle and sags at the knees.

Module 7Level 4deflected shape

Does a symmetric portal sway under gravity?

A symmetric portal frame carries a symmetric gravity load on its beam. Which deflected shape is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

No sway: the beam sags symmetrically and the columns bend outward a little, but the frame does not lean to either side.Option B

The frame sways to one side as it takes up the load.Option C

The beam sags but the columns stay perfectly straight and vertical.

Module 7Level 4bending moment

Bending moment of a fixed-base portal under horizontal load

A fixed-base portal frame is pushed sideways by a horizontal load. Which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

Moment at the fixed bases and at the knees, with the columns bending in double curvature (the moment changes sign up the column).Option B

Zero moment at the bases, exactly like a pinned-base frame.Option C

The moments are the mirror image, hogging where the frame really sags.

Module 7Level 4change

Add a diagonal brace to a swaying frame

A pinned-base portal sways badly under horizontal load. A diagonal brace is added across the frame. What happens?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The sway almost disappears: the brace carries the horizontal load as axial force through a triangulated path.Option B

The sway is unchanged, because the brace only adds weight.Option C

The frame sways the other way now.

Module 7Level 3bending moment

A load on the arm of a cantilever frame

An L-shaped cantilever frame — a fixed column with a horizontal arm — carries a downward load at the tip of the arm. Which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

Moment grows along the arm to the corner and continues down the whole column to the fixed base.Option B

Only the arm bends; the column carries pure axial force with no moment.Option C

The moment is largest at the free tip and zero at the base.

Module 7Level 3deflected shape

How a pinned-base portal sways

A portal frame with pinned bases carries a horizontal load at the top of one column. Which deflected shape is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The whole frame leans in the direction of the load; both columns bend in single curvature and the beam stays roughly straight as it rides across.Option B

The frame does not move, because the beam is rigid.Option C

The frame leans against the load, in the opposite direction.

Module 7Level 3bending moment

Bending moment in a swaying portal

For the pinned-base portal under a horizontal load, which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

Zero moment at each pinned foot, rising up each column to a peak at the knee, and carried across the beam — the columns clearly bend.Option B

Moment only in the beam; the columns carry pure axial force.Option C

The largest moment is at the pinned feet.

Module 7Level 4deflected shape

Column shape of a fixed-base portal

A portal frame with FIXED bases sways under a horizontal load. What shape do the columns take?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

Each column bends in double curvature — an S-shape with an inflection point partway up — because both the base and the knee resist rotation.Option B

Each column bends in a simple single curve, like a pinned-base portal.Option C

The frame does not sway at all, because the bases are fixed.

Module 7Level 4bending moment

Where the moment goes in a fixed-base portal

For the fixed-base portal under a horizontal load, which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

Moment appears at the fixed feet AND at the knees, with opposite signs on each column — so the moment reverses partway up.Option B

Zero moment at the feet, exactly like a pinned base.Option C

The columns carry no moment; only the beam bends.

Module 7Level 4bending moment

Gravity on a pinned-base portal — bending moment

A portal frame with pinned bases carries a uniform gravity load on its beam. Which bending-moment diagram is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The beam sags in the middle and hogs at the knees, and that knee moment runs down the columns to zero at the pinned feet.Option B

Only the beam carries moment; the columns are moment-free struts.Option C

The beam hogs in the middle and sags at the knees.

Module 7Level 3deflected shape

Deflection of an L-shaped frame

An L-shaped frame has a fixed column with a horizontal arm cantilevering off the top. A load hangs at the arm tip. Which deflected shape is correct?

Predict first, then reveal

Choose the response that obeys the supports, joint continuity and equilibrium — not the one that looks familiar.

Option A

The arm tip drops sharply, and the rigid joint carries that rotation into the column, which bends over towards the load.Option B

Only the arm droops; the column stays perfectly vertical.Option C

The arm tip lifts upward.