Module 18 · Level 4 · reactions and load path
Reading an overhang in full A load sits on the overhang of a beam beyond its far support. Which single statement reads the whole response correctly?
Predict first, then reveal Reason from the supports, the movement and equilibrium — not from what looks familiar.
A The back span hogs, the far (near) support pushes up hard while the other reaction reverses to a hold-down, and the moment is zero at the pin and at the free tip. B The beam sags between the supports and both reactions push up, as for a normal simple span. C The moment is largest at the free tip, where the load is.
Commit answer and reveal Hint
Module 18 · Level 5 · change and sensitivity
One loaded span, several consequences In a three-span continuous beam, only the middle span is loaded. Which reading joins the consequences correctly?
Predict first, then reveal Reason from the supports, the movement and equilibrium — not from what looks familiar.
A Continuity hogs the beam over the interior supports and lifts the unloaded end spans, so the end reactions reverse downward — and unanchored end bearings can lift off. B Only the middle span responds; the end spans do nothing. C All three spans sag downward together.
Commit answer and reveal Hint
Module 18 · Level 4 · deflected shape
A portal under symmetric gravity A symmetric portal frame carries a symmetric gravity load on its beam. Which combined statement is right?
Predict first, then reveal Reason from the supports, the movement and equilibrium — not from what looks familiar.
A It does not sway (symmetry), but the columns still bend, because the rigid joints transfer the beam's end moments into them. B It sways to one side and the columns carry only axial force. C The columns stay straight because only the beam is loaded.
Commit answer and reveal Hint
Module 18 · Level 4 · stable or mechanism
How close to a mechanism? An all-pinned rectangular portal is currently a sway mechanism. Judging its sensitivity, what is the smallest change that would make it stable?
Predict first, then reveal Reason from the supports, the movement and equilibrium — not from what looks familiar.
A Any one of: make a single joint rigid, fix one base, or add one diagonal brace — each alone removes the sway mechanism. B Nothing short of rebuilding it entirely will help. C Adding more pinned members, to increase the count.
Commit answer and reveal Hint
Module 18 · Level 3 · software check
Why qualitative judgement matters With powerful analysis software available, why is the qualitative judgement taught in this course still essential?
Predict first, then reveal Reason from the supports, the movement and equilibrium — not from what looks familiar.
A Because software gives magnitudes but not validation — only a prediction of the behaviour lets you tell whether a converged result describes the structure you meant. B It is not — modern software makes hand judgement obsolete. C Only so you can do the sums faster by hand.
Commit answer and reveal Hint
