What is an expansion roller?

Bridges can be expanded or downloaded due to several factors such as traffic load, materials used in construction and temperature. For example, when the temperature is hot, the bridge extends to length and when the weather cools down, it is withdrawing. The extension cylinder allows a small rigid -constructed bridge to expand and securely care for the length. Sed is a triangular structure of the bridge, with all parts connected together by intersections called nodes. The expansion cylinder consists of joints formed with sticks that move when the bridge expands. The expansion rollers are included in the bridges of 80 feet (24.4 meters) and longer to ensure the safety of the bridge at all times. While the expansion and contractions of each part of the bridge can be very small because the bridges are extended, it can be a big problem.

When temperatures rise, the materials used to build the bridge Cross or increase the length. The more the temperature increases, the more the materials will increase. Expanding rollers allow, abThe sections moved so that the extra length did not cause the bridge to switch and even broke. As the temperatures cool down, the bridge building materials are downloaded or decreased. In this case, the expansion rollers allow to move parts of the bridges so that they connect and the gaps do not occur in the bridge.

In addition to the weather, other factors can also cause the bridge to be expanded and contraction. Expansion and contractions may be caused by the process of curing concrete, moving the ground and heavy loads of the bridge for a long time. The extension cylinder is a type of bearing that makes these otherwise harmful factors that are not harmful to the bridge.

bridges must be checked and regularly checked as the rest of the Highway Infrastructure. The expansion cylinder can be corroded and ineffective due to road salt, dust and aging. Corrosion is the most common damage that affects the durability and life of the bridge. For exampleIn 2007, the InterState 35 West Bridge, in Minneapolis in Minnesota, collapsed because of the frozen, corroded, 40 -year expansion rollers that did not work properly. The lack of the ability to expand was due to the damaged expansion cylinder and led to suppression of tension in Most and the strut and collapse of the integral horizontal beam.