A measurement apparatus for determining a bending moment acting on a hollow cylindrical body in a current state as well as to a method of operating such a measurement apparatus. The measurement apparatus may include a sensor support structure, a sensor arrangement with sensors, and a processing system. The processing system may determine displacements of the inner surface of the hollow cylindrical body relative to the sensors based on the distances measured in the current state compared to the distances measured during an initial undeformed state, and determine the bending moment acting on the hollow cylindrical body based on the displacements.