Construction and Installation of Prefabricated Beams for Houses
The construction and installation of prefabricated beams for houses mainly include key steps such as construction preparation, steel bar processing and binding, formwork installation, concrete pouring, prefabricated beam installation, and subsequent construction.
During the construction preparation phase, it is necessary to reasonably arrange the site, set up a prefabrication yard, steel bar and steel strand processing yards, etc. At the same time, construct beam-making pedestals and beam storage pedestals. The pedestals consist of foundations and pedestals, with the pedestal surface made of high-strength reinforced concrete. Prepare materials such as steel bars, steel strands, and anchors, as well as equipment like mixers and gantry cranes.
In the steel bar processing and binding step, in the steel bar processing area, cut, bend, and process the steel bars according to the design drawings and specification requirements to ensure that the dimensions, shapes, and quantities meet the design standards. Bind them into shape in sequence on a dedicated steel bar binding pedestal, such as first binding the bottom-plate bottom-layer steel bars, then binding the web and flange-plate stirrups, etc. The prestressed pipes in the beam are positioned and fixed with “#”-shaped positioning steel bars.
When installing the formwork, first clean the formwork and apply a release agent. Place the bottom formwork on the beam-making pedestal and adjust its position and elevation. Use a gantry crane to lift the side formwork to the designated position, connect it firmly with the bottom formwork, and adjust the perpendicularity and flatness of the side formwork. The inner formwork is erected after the bottom and web steel bars are bound into shape. It is assembled into a whole in sections outside and then installed in place with a gantry crane.
During the concrete pouring process, strictly prepare the concrete according to the mix proportion at the mixing plant to ensure that the workability and slump meet the requirements. Transport it with a concrete mixer truck to prevent segregation. Usually, start pouring from one end of the box girder, first pour the bottom plate and then the web. When pouring the web, pour it segmentally in the longitudinal direction and layer by layer in the horizontal direction towards the other end. Use high-frequency attached vibrators as the main method and immersion vibrators as an auxiliary method to vibrate the concrete.
When installing the prefabricated beams, mark a 10-mm control line for the length of the prefabricated beam placement on the prefabricated columns. Install the support frame, place a 20-mm-thick wooden pad under the support, use adjustable bases at the bottom and top, connect the frame with 48-mm-diameter steel pipes and couplings, use 48-mm-diameter steel pipes as the main beams, and 50*100-mm square timbers as the secondary beams. Use a beam-lifting spreader to lift the prefabricated beams, hang the hooks on the lifting points, place them steadily, and then unhook. Re-measure the elevation of the prefabricated beams, with an allowable error controlled within 5 mm. Install other prefabricated beams in sequence and re-measure their elevations.
In the subsequent construction, after the concrete reaches the tensioning strength, carry out the prestressed construction. Extract the inner liners, thread in the steel strands, install and tension them, cut off the excess steel strands, install the grouting pipes, and perform grouting. After the concrete strength reaches 100%, carry out the bridge deck leveling and waterproofing construction. Finally, pour the asphalt concrete bridge deck using the wet joint process.
