If elongating steel pushes out loadbearing walls and the walls can withstand the elongation, what is the likely consequence?

• A. The steel will fail and sag somewhere in the middle, causing collapse of upper floors or the roof
• B. The walls will buckle outward
• C. The roof will rise
• D. The foundation will lift

Answer: (A)

When a steel member lengthens while its ends are held in place by loadbearing walls, the extra length has to be accommodated somewhere. If the walls keep their position, the beam can’t slide or rotate to match the longer length, so it bends. The midspan is where bending is greatest, so the steel section yields and deflects upward or downward there, causing a pronounced sag. As the steel loses stiffness with continued elongation, that midspan sag can reach a failure point, leading to the collapse of the floors it supports or the roof above. If the walls were to buckle outward, that would be a different failure path, but in this scenario they tolerate the elongation, so the most likely outcome is midspan flexural failure and progressive collapse of the upper structure. The other options describe vertical movement rather than bending of the beam, which isn’t driven by elongation with fixed ends.