Prestressed concrete beam I

Ifor bridge construction

BRIDGE BEAMS FOR ROADS, HIGHWAYS, RAILWAYS (INCLUDING HIGH-SPEED RAILWAYS), TUNNELS, ETC… ARE MANUFACTURED USING MAINLY I AND V PROFILES WITH PRE-STRESSED OR POST-STRESSED REINFORCEMENT RODS. Such beams are made of high-performance concrete pre-cast into multi-section metal formworks, vibrated at high frequency and quickly cured by an appropriate thermal cycle. Concerning pre-stressed beams, the pre-stressing process is performed by stretching each single-strand and then anchoring the latter on the stretching heads. When the necessary concrete resistance is achieved, strands are released and then cut. The whole production cycle is complete within one day. Concerning post-stressed beams or sliding-cables beams, before casting concrete into the formworks, it is necessary to arrange standard reinforcement and sheaths. These latter serve as accommodation for pre-stressing cables which carry special anchorages at their edges. The concrete is compacted by high frequency vibration. Once also the curing process is complete, the cables are inserted into the sheaths and the stressing is performed by specific stressing machinery. Pre-stressed I beams have length from 500 to 1.500 mm. height from 800 to 2.500 mm., casting thickness from 100 to 300 mm; pre-stressing up to 1.800 ton. The beams when assembled can be positioned side by side or spaced. They are joined together by an on-site additional casting forming a slab to better distributes loads crosswise. The max. length of pre-cast pre-stressed beams is 40 mt.