noun
bridge girder
Refers to the horizontal structural beam supporting a bridge deck. Common in civil engineering and construction contexts.
橋桁の点検が行われた。
An inspection of the bridge girders was carried out.
新しい橋桁が設置された。
New bridge girders were installed.
橋脚 refers to bridge piers (vertical supports), while 橋桁 refers to the horizontal girders.
Compound of 橋 (はし, 'bridge') and 桁 (けた, 'beam, girder'). The reading はしげた is a straightforward combination of the kun'yomi readings.