Rigorous Material Inspection: Conduct on-site destructive sampling tests for rubber bearings, such as using portable Raman spectrometers to detect rubber composition (characteristic peak of natural rubber at 2920 cm⁻¹), to avoid substandard bearings with excessive reclaimed rubber content. Perform hydrogen embrittlement testing on embedded bolts (e.g., tensile testing after immersion in a 5% sulfuric acid solution for 48 hours)
Correct selection: Choose the type of bearing (plate, pot, or spherical bearing) based on the bridge span, load grade, displacement (e.g., ±50mm/±100mm), and seismic requirements. In seismic zones, use bearings with seismic blocks or high-damping rubber bearings
Pad stone and beam bottom treatment
Precision control of cushion stone: 6mm thick steel plate is used as the template, with a spacing of ≤ 30cm between the back ribs, ensuring that the flatness error of the cushion stone after pouring is ≤± 1mm. Before the initial setting of concrete, use a 3D laser scanner to detect and immediately repair any areas exceeding the tolerance limit (>2mm)
Beam bottom treatment: The pre embedded steel plate of the prefabricated beam bottom support needs to be firmly welded to the steel bars of the beam body, with a plane height difference of ≤ 1mm. During the construction of the cast-in-place beam, non shrinkage grouting material (strength ≥ C40) is used to grout the anchor bolt holes to ensure compactness and no bubbles
Installation process control
Accurate positioning: Use a total station to locate the centerline of the support, with a longitudinal and transverse deviation of ≤ 5mm and an elevation deviation of ≤ 2mm. The activity support should be set with a pre offset according to the design requirements (such as pre offset towards lower temperatures when the temperature is higher than the average temperature)
Temporary support: The jacks need to be symmetrically arranged, with a lifting height not exceeding 1/2 of the support height to avoid tilting of the beam. Before the precast beam falls, a 2mm thick PTFE sliding plate should be laid on the top surface of the support and slowly positioned
Finished product protection and monitoring
Pollution prevention: During the pouring of beam concrete, prevent cement slurry from splashing onto the surface of the support, which may affect the sliding performance
Intelligent monitoring: When installing the fiber optic strain monitoring system, the sampling frequency should be adjusted according to the construction conditions (such as ≥ 1 time/second for the lifting process), and a dynamic warning threshold mechanism should be established.
Through the above measures, common problems such as material defects, positioning deviations, and voids in the installation of bearings can be effectively avoided, ensuring the safety of bridge structures.