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In precast segmental box girder bridges, the bridge segments are usually formed by match casting. It is sometimes observed that a gap is formed between adjacent bridge segments. Why?

In precast segmental box girder bridges, the bridge segments are usually formed by match casting. It is sometimes observed that a gap is formed between adjacent bridge segments. Why?

To enhance perfect fitting of bridge segments in precast segmental box girder bridges, segments are usually constructed by match casting so that it would not impair the serviceability and load bearing ability of the bridge. The end face of completed segment is adopted as formwork for the new segment. During the concrete hardening process, the hydration effect of new segment induces a temperature rise and develops a temperature gradient in the completed segment. Hence, the completed segment bows temporarily and the new segment sticks to this bowed shape when hardened. After match casting, the completed segment retains its original shape after cooling down while the new segment obtains the profile of bowed shape. Such bowing effect is even more significant for slender segments with large height to width ratio.

gap is formed between adjacent bridge segments

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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