Installation of Building lead rubber bearing
We need to follow the installation order of the lead rubber bearing, The installation construction order for the building lead rubber bearing is from the bottom to the top, that is to say, we must finish the construction of the substructure components or base of the LRB before we start to install the bearing.
During the process of installation, we need to keep record for the construction, and record and observe the horizontal degree of the top surface of lead rubber bearing bottom embedded plates, plate position of the lead rubber bearing center, and the standard level.
A: special tools used for installing LRB
The tools using for the construction need to be prepared before hand and adjusted. And the tools we need are: theodolite, marker post, leveling instrument, box staff, folding ruler, angle square, and objecto pendente and so on.
B:The quality requirements of building lead rubber bearing in the process of installation
To ensure the rubber bearing is the axial compression as much as possible, therefore, we have high requirements for the controlling precision of rubber bearing horizontal degree and axis position. The national related standards are as follows:
(a) Before the installation of the LRB, the horizontal degree of the bottom installation surface deviation should be less than 5%; after the installation of the rubber bearing, the horizontal degree of the top surface deviation should be less than 8%;
(b) The deviation between the plate position of the lead rubber bearing and design position should be less than 5.0mm;
(c) The deviation between the installation level of the lead rubber bearing and the design level should be less than 5.0mm;
(d) When we need to pour the concrete at the second time, we need to use the fine aggregate concrete that is one level higher than the initial components.
C: The specific installation steps for the building lead rubber bearing
(a) The embedded bolt and adjustment bolt is delivered with the building LRB. Screw the embedded bolt and adjustment bolt that connect the bottom embedded plate into the threaded hole of the bottom embedded plate in order to prevent the concrete going into the threaded hole during pouring the concrete.
Att: The reserved length after the bolt screwing in should ensure the fastening of the lead rubber bearing’s connecting plate and embedded plate.
(b) Mark the centerline as “+” on the top surface of the embedded plate;
(c) Place the embedded plate on the design position according to the embedded plate center line, place the embedded plate on the form work to support and fix its position, or fix the embedded plate by the ways of erecting bracket hanging
(d) Adjust the horizontal position, standard level and evenness of the embedded plate
Adjust the horizontal position of the embedded plate according to the embedded plate centerline, and adjust the standard level and evenness by adjusting the screw or wood wedge. During the adjustment process, we measure the standard level of the embedded plate by leveling instrument, measure the horizontal degree of the embedded plate by horizontal ruler, and measure the center position by graticule.
(e) After adjusting the center position, standard level and evenness of the embedded plate to meet the requirements, connect the embedded bar of the embedded plate with the major steel bar on the base.
(f) After the connecting of the embedded bar of the embedded plate and the major steel bar on the base,check again the embedded plates’ center position, standard level and horizontal degree.
(g) Pouring concrete.During the process of pouring the concrete, remove the support staff of the embedded plate at the appropriate time.
(h) When the concrete intensity comes to a certain degree, loosen the bolt on the embedded plate in time, to prevent mortar that comes into the gap of the threaded hole from fastening the bolt.
(i) As the concrete will shrink after solidification, the space between the embedded plate and concrete need to be filled, to ensure the embedded plate and concrete are tight closely.
(j) After the solidification of the concrete, remove throughly the cement of the embedded plate in time.
(k) When the concrete intensity after solidification reaches the requirements, install the lrb . Screw off the bolt installed on the embedded plate, and install the lead rubber bearing on the embedded plate. Before fastening the bolt, check again the horizontal degree of the lead rubber bearing. If the horizontal degree can not meet the requirements, it is allowable to install the adjustment pad between the lead rubber bearing and the embedded plate, and then tighten the lead rubber bearing.
(l) Install the top embedded plate.Install and fasten the top embedded plate and seismic isolation pad. Then, the installation of seismic isolation bearing is over.
(m) Set up the formwork. During the process of setting up the formwork, pay attention to the fact that there is no gap between the formwork and the seismic isolation pad of the embedded plate. Ensure no mortar leaking during pouring concrete.
When installing LRB on building construction, we need to follow above process and details.After installation, maintenance and inspection of lrb should be carried out according to regulations
