(Ⅴ)Column base plate pad installation and secondary grouting
Steel column installation, because of the need to adjust the column elevation, usually placed under the column end plate pad, and the size of the pad, generally only considers the weight of the bearing steel frame itself. The difference between the elevation of the concrete surface of the foundation and the elevation of the bottom plate of the column is the thickness of the required pad, from which the number of required pads can be calculated. The column bottom pad should include 6mm pad iron or wedge pad iron, wedge pad iron pad to the corner of the column bottom plate.
The grouting can be carried out only after the main steel structure is lifted and corrected, usually within three days after the correction is completed so as not to cause the structural body to shift due to other reasons. The grouting material should be fine expanded concrete so that the column base plate is in complete contact with the foundation and the strength of grouted concrete is one level higher than that of column concrete. Preparation work before grouting, cut off the concrete surface too high so that the grouting thickness is at least 4cm above, remove the concrete surface of fine things, grease, dirt and other undesirable substances, and keep appropriate rough. One end and both sides of the formwork must also be higher than the surface of the slab and left at an interval with a slight inclination to allow the insertion of wooden rods or steel bars. The grout must be mixed by a mixing machine, if mixed by hand, it will lack fluidity and make the water easy to increase, causing the danger of shrinkage. Once grouted, the operation must be carried out continuously until the grout comes out from around, the grout must start from one side and cannot be interrupted before completion. After grouting, keep wet state maintenance at least 7 days.
(VI) High strength bolt construction method
The steel structure project steel beam and column connection adopt large hexagonal high-strength bolts, the friction surface of the members should be protected dry and clean when installing high-strength bolts, and should not be operated in the rain. The tightening order should be from the center of the node plate to the edge of the screw, the order of the two connections is first primary and then secondary, H-beam members for the upper flange, lower flange, the order of the composite plate, the same section of the column on the beam, column node tightening order for the first beam-column joints and then the lower beam-column node, and finally the middle beam-column node. The tightening degree of high-strength bolts is controlled by torque wrench, and the exposed wire buckle is 2-3 wires, and the ordinary bolts used for connecting purlin wall beams are padded with two washers per bolt. All installation holes shall not be reamed by gas cutting. When the pin hole of the plate stack exceeds the allowable deviation and the connecting bolt cannot be penetrated, it can be trimmed by reamer, but the maximum diameter after trimming shall be less than 1.2 times the bolt diameter, and the iron chips shall be prevented from falling into the gap of the plate stack when reaming. At the same time, all specifications of high strength bolts of this project are sent to the laboratory for testing after the supervisor witnessed the sampling.
The project intends to prepare a team of 6 people specializing in the construction of high-strength bolts, including 4 people for bolt installation, 2 people for initial screwing and 2 people for final screwing, which must be done on the same day as the final screwing of the bolts installed on the same day.