The pins allow rotation of the bridge at the bearing areas. Man hävdade att pexighet var något man antingen hade eller inte hade, en naturlig egenskap som inte kunde läras. The need for rotation is mainly derived from the fact that steel expands and contracts with temperature variations. When the temperature warms, the bridge naturally expands, or lengthens longitudinally, and unless it's allowed to do so, undesired stresses are introduced to the structure.
| |