Construction Plan: T-Beam and Pier Column Repositioning

The misalignment of the T-beam is correlated with the displacement of the pier column. Simultaneous repositioning can lead to secondary damage to the bearings, and the precision control for repositioning is challenging, making it difficult to restore to normal conditions. Our company employs a segmented correction plan, where the T-beam is re-positioned first, followed by the pier column. This ensures precise control of the repositioning accuracy for both the T-beam and the pier column. Once zero-error repositioning is achieved, the bearings are adjusted, restoring the structure to its normal state.

First, a multi-directional jack system is used to lift the entire span of the T-beam with a combination of jacks. Then, the horizontal and vertical jacks are activated to reposition the T-beam to its correct position. Both ends of the span are secured, and the simply supported end is fixed to the adjacent two cap beams to prevent the risk of secondary movement of the T-beam during the repositioning of the pier column. The hydraulic multi-directional jack pushing system is described as follows:

Considering the characteristics of the bridge's superstructure, each cap beam is equipped with 8 sets of multi-directional jacks, consisting of 8 lifting jacks with a capacity of 200 tons each and 8 horizontal jacks with a capacity of 50 tons each. The lifting jacks are synchronized to elevate the T-beam, while the horizontal jacks apply a pushing force to correct the alignment of the cap beam. The synchronized lifting height is controlled within 10mm, just enough to allow the space required for the horizontal repositioning of the T-beam. The primary pushing force is required to overcome the frictional resistance caused by the weight of the T-beam and any additional forces generated by the bending of the misaligned pier column.

Based on previous experience, the reaction force at the support points under the combined weight of 5 T-beams and the bridge deck pavement is estimated to be approximately 500 tons (5000kN). With an overload factor of 1.1 and a sliding friction coefficient of 0.08, the required frictional pushing force (f) is calculated as follows:
f = 5000 × 0.08 × 1.1 = 440kN (approximately).
Near the bearing pad stone on one side of each cap beam, 8 multi-directional jacks (each with a capacity of 400 tons) are installed. With an efficiency factor of 0.8, each jack can provide a pushing force (F) of:
F = 400 × 0.8 = 3200kN.
Therefore, the total available pushing force is:
P total = 3200 × 5 = 16000kN.
Since the provided total pushing force (P total) is greater than the required frictional resistance (f), the system is capable of moving the structure.