Technical parameters of spherical bearings
No. | ITEMS | THECNICAL REQUESTS |
1 | Bridge spherical bearings | 1000-100,000 KN |
2 | Angle ratio | 0.02 rad |
3. | Horizontal force | 15%,20%,30% of vertical loading |
4 | Max displacement | ±100mm, ±150mm |
5 | Designing frictional coefficient | ≤0.03 |
6 | Adjustment hight range | 0-20mm |
7 | Applicable range of slope | no slope on the top surface of the top plate of spherical bearing , and the slope of the bridge is adjusted by the beam concrete |
Installation and anchoring of spherical bearings
1. Installation of spherical bearings on simply supported beam
1) The installation of spherical bearing on prefabricated simply supported is anchored using bolts and sleeves. The sleeves are spot welded and fixed to the connecting steel plates, and is embedded at the bottom of the beam.
2) When lifting the beam, pay attention to checking the corresponding tonnage used of beam, and install the slope matching bridge bearings at the bottom of the prefabricated beam according to the slope requirements. There should be no gap between the upper seat plate and the embedded steel plate at the bottom of the beam.
3) Clean impurities from the reserved anchor bolt holes, install a grouting template, and wet the surface of the bridge spherical bearing stone with water. The grouting template can use prefabricated steel molds, with a layer of rubber leak proof strips installed at the bottom,and fixed to the top surface of the support plate stone by expansion bolts.
4) Lift the prefabricated beam body (with spherical bearing), place the beam body on the temporary support jack, adjust the position and elevation of the beam body through the jack, and the difference in reaction force of each jack shall not exceed 5% of the average value.
5) After the support is in place, there should be a 20-50 gap between the bottom plate of the spherical bearing and the top surface of the bridge pier or abutment support plate stone, so as to pour non shrinkage height grouting material. The compressive strength of the grouting material should not be less than 50MPa.
6) By using gravity grouting method, the lower part of the bridge spherical and anchor bolt holes are grouted. The grouting process should be carried out from the center of the bridge spherical bearing to the surrounding areas, until the grouting material is fully filled , this situation can be saw from the gap between the template and the spherical bearing bottom plate.
7) Before grouting, the required volume of grout should be calculated, and the actual amount of grout injected should not too much error with the calculated value , grout shortage is not allowed
8) Before dismantling the temporary support point, the bridge erecting machine should pass through the hole rigorously. When dismantling the temporary support point, the strength of the grouting material should not be less than 20MPa.
9) After the strength of the slurry reaches the specified strength, remove the steel form work, check for any leakage, and if necessary, supplement the leakage,
10) Tighten the anchor bolts of bottom plate of the spherical bearing, and remove the upper and lower support connection bolts of each spherical bearing, as well as the temporary support jack.
Anchorage of bridge spherical bearing
1) Anchorage of spherical bearings and cast-in-place beams
When installing spherical bearings on cast-in-place beams, first use anchor bolts to fix the ceramic screw to the top plate of spherical bearing. If there is a pre embedded steel plate, it should be fixed by spot welding and using the sleeve. Then, along the top surface of the spherical bearing , the large beam body template should be outward. Once it is completed, pouring can be carried out.
2) Anchorage of spherical bearings and prefabricated beams
For bridge bearings used for precast concrete continuous beams, pre spot welding is used to fix the embedded sleeve on the embedded steel plate at the bottom of the beam, and then anchor bolts and the embedded sleeve installation method are used to install the spherical bearings . The embedded steel plate should be pre drilled according to the spacing requirements of the anchor bolts on the bridge bearing plate, with a diameter should be 2mm larger than the sleeve diameters.
When using this method for installation, attention should be paid to ensuring that the position of the embedded steel plate on the precast beam is consistent with the installation position of the spherical bearing on the pier, this ensure that the position of the embedded sleeve corresponds to the position of the bolt holes on the spherical bearing .
