Multispan Stayed Girder Bridges

In stayed girder bridges with two or three spans the horizontal displacement of pylon tops is prevented by the so-called fix-cables, i.e., upper end span cables. If stayed girder bridges are constructed with several equal main spans the intermediate pylons will tend to move horizontally under one-sided loading. This induces a rotation of the entire cable system giving unacceptable vertical deflections of the stiffening girder. To obtain the necessary stiffness two measures might be taken, either application of triangular pylon structures with sufficient horizontal rigidity at the top, or introduction of a horizontal fix-cable (tie) connecting all pylon tops.