Arch bridges - Computational Analysis and Design of Bridge Structures - page 293

Figure 9.20 LiujiangYellow River Bridge, Zhengzhou, China. (Courtesy of mudedi.59706.com.)
As shown in Figure 9.21, the arch bridge is modeled three-dimensionally
by using frame and truss elements. The arch, lateral bracings, tied gird-
ers, floor beams, and deck slabs are modeled by frame elements; hangers
are modeled by truss elements. As there is no lateral load included in the
analyses, the stringers simulating deck slabs are located at the centroids of
floor beams. There are 1018 elements in total. The analyses include dead
load analysis with an automated hanger tuning for a preferable moment
distribution on tied girders and live load analysis.
Figure 9.22 shows moment and axial force distributions without
tuning of hangers. It can be seen that the moment distribution on tied
girder is similar to a simply supported girder, and tensions in hangers
are low when hangers are not prestressed. Figure 9.23 shows a preferred
distribution achieved by automated hanger tuning analysis, in which
tied girder works like a multiple-supported continuous girders. Tensions
in hangers are higher. Figure 9.24 shows the moment and axial force
envelopes due to live loads. Figure 9.25 shows the moment and axial
force distributions under live loads that cause extreme compression at
the crown on one arch. The uneven distribution of live loads is clearly
displayed.