Which characteristic of fixed bearings is crucial for bridge stability?

The characteristic of fixed bearings that is crucial for bridge stability is their ability to allow for rotation. Fixed bearings are designed to provide support that restricts movement in the horizontal directions while accommodating rotation. This rotation is important because it allows the superstructure of the bridge to respond to thermal expansion, contraction, and deflections due to applied loads without compromising overall stability.

While fixed bearings constrain horizontal and translational movements to ensure the structure remains firmly in place, they must still adapt to changes in angle which occur as the bridge experiences various forces and temperature fluctuations. This unique capacity for rotation helps maintain the integrity and functionality of the bridge, contributing significantly to its durability and safety.

In contrast, allowing for movement, facilitating translational movement, and permitting vertical adjustment involve varying forms of flexibility that are not compatible with the fundamental purpose of fixed bearings, which is to maintain a stable configuration under dynamic loads while restricting specific movements.