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What is the significance of null point in bridge deck?

The null point is the position of zero movement in the bridge deck. When the bridge deck is pinned at a single pier, it provides the location of null point with no deck movement. However, when the bridge deck is pinned to more piers, the position of null point has to be calculated. The determination of null point is important because it serves to estimate the forces on the piers by deck length changes and to calculate the sliding movement of sliding and free bearings.

For symmetrical deck founded on two identical fixed piers, the null point should be midway between the two fixed piers. However, if one pier is taller than the other, the null point would be shifted to the shorter stiffer pier.


This question is taken from book named – A Closer Look at Prevailing Civil Engineering Practice – What, Why and How by Vincent T. H. CHU.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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