The steel structure building construction typically involves the following steps: laying the foundation, erecting the main framework, installing secondary structures and purlins, installation of roof and wall panels, completing edge finishing and flashing, and fitting doors and windows.
1. Steel structure building construction: Pre-embedded anchor bolts
The professional civil engineering team is responsible for the foundation construction of the steel structure buildings. Once the short-column steel bars are bound, and the formwork support is firmly reinforced, professional technicians and construction personnel are responsible for pre-embedding the steel structure bolts. Therefore, it is crucial to strictly control the position, extension length, levelness, and elevation of the foundation support surface during pre-embedding.
The following are the key points to consider during bolt pre-embedded construction:
Utilize prefabricated drilling steel molds: Installing bolts can be made more efficient using factory-made drilling steel molds.
Inspect anchor bolt position and elevation: After the anchor bolts are installed, ensure that the height of the first thread at the lower end of the bolts meets the requirements. If acceptable, weld the bolts firmly to the steel mesh.
Protect the thread: To prevent damage to the anchor bolt thread during or before installation, protect it with a protective sleeve.
2. Steel structure hoisting
2.1 Hoisting preparations for steel structure building construction
A complete retest is necessary for all foundation anchor bolts to ensure compliance with the design requirements and relevant construction specifications. The bolts must also be cleaned, oiled, and their elevations rechecked to ensure they are correctly installed. Moreover, the overall axis and column-to-column dimensions should be reviewed to guarantee they meet the design requirements and relevant construction codes.
2.2. Hoisting method
The primary structure is lifted using a truck crane, while secondary components and plates are lifted manually. Steel columns are raised using a single-machine rotation method. When hoisting roof beams, they should be assembled and corrected on the ground before lifting. Human assistance can be used for lifting and extra assembly support if necessary.
2.3. Lifting and correction of steel column
First, to lift the steel column, bind it and the lifting point with a steel wire rope attached to a car crane. Tie the steel column at one end with a cable wind rope to assist in lifting. Before hoisting, it’s essential to perform a trial lift to ensure the safety of the operation. When boosting, the crane should lift the bound column slowly, raising it 20 cm above the ground. The crane operator should pause to ensure the sling is secure, the crane is stable, and the slewing brake is engaged. Next, lower the steel column to a position 40-100 mm away from the installation surface, align it with the reference line, and command the crane to descend so that the column can be inserted into the anchor bolt and temporarily fixed. After a preliminary correction, the verticality deviation of the steel column should be controlled within 20 mm before unhooking the crane. Check the column’s verticality using a theodolite, and correct any deviations immediately. During the calibration process, observe whether there is any space between the bottom and the height control pad to prevent any level errors.
2.4 4. Lifting and correction of steel beams
After the steel beams arrived, the first step was to assemble them. Once the steel beams were flipped into place, several trial liftings were necessary to ensure the slings’ stability and that they were re-lashed on time. During the trial lifting process, it is essential to lift slowly to ensure that the force on each lifting point is evenly distributed and that the steel beam is not deformed. Once the requirements are met, the steel beam can be hoisted and rotated into the designed position. Next, use the control rope, pre-fastened on the rafter, for positioning. Next, use a wrench to determine the hole position of the column and beam and fix it with high-strength bolts. It should be noted that for the first steel rafter, two temporary fixing cables should be added, and for the second and subsequent girders, roofing sandalwood strips or tie beams should be used for quick fixing.
2.5. Grouting mortar
To install a steel column, the leveling nut of the anchor bolt must be used to adjust its height. However, grouting mortar should only be done after hoisting the primary steel structure. Fine stone expanded concrete is recommended for the grouting material to ensure the column bottom plate is entirely in contact with the foundation. Additionally, the strength of the grouting concrete should be one level higher than the column concretes.
Before grouting, some preparatory work is necessary. Firstly, the excess concrete surface must be removed to ensure a thickness of at least 4 cm for the grout. Secondly, fine substances such as grease and soil must be removed from the concrete surface, leaving an appropriate roughness. Finally, one end and both sides of the formwork must be higher than the board surface and inclined to insert wooden rods or steel bars.
After preparing the work, a mixer should be used to mix the grout. However, mixing by hand is not recommended as it can increase water content, leading to shrinkage risks.
Once pouring has begun, work should continue until the grout comes out of the surroundings. Pouring should start from one side and should not be interrupted before completion. After priming, the grout must be kept moist and maintained for at least seven days.
2.6. Construction method of high-strength bolts
High-strength bolts must be used when connecting steel beams and columns to ensure the component’s friction surface is dry and clean. Do not operate in rainy conditions. Tightening the bolts should be done gradually, starting from the center of the gusset plate and working toward the edge. When connecting two parts, the primary connecting part should be tightened first, followed by the second. The upper flange, lower flange, and double plate should be drawn in that order when connecting H-shaped steel members. For beam and column joints on the same column, tighten the upper beam-column joint first, then the lower beam-column joint, and finally, the middle beam-column joint.
3.1 Steel structure building construction for Roof and wall panel
The purlins and bracing system must be compatible with the hoisting of the primary steel structure. The pulley borrowing method can install steel structure purlins, but aligning the screw holes and ensuring the appropriate tightening degree is essential. Depending on the purlin’s specification and use position, it must be manually suspended and installed at the corresponding location on the Roof or wall facade.
Typically, flange bracing is connected to ground-level roof beams before being bolted to roof purlins after hoisting. Therefore, when installing the Roof and wall tie rods and tie rods, it is crucial to promptly adjust the purlin levelness and correct issues like bending deformation caused by transportation or stacking.
3.2. Steel structure building construction for Roof panel and trim
The roof panels are delivered to the construction site by truck crane, and the installation sequence is determined based on the site conditions. The first step is installing the roof panel next to the gable wall. Once the first panel is in place, an alignment line is drawn on the roof eaves to serve as a reference point for subsequent installation and correction. This ensures that the following panels are installed quickly and accurately. Throughout the installation process, it is essential to periodically check the width of each panel, including the ridgeline and cornice, to ensure their parallelism and perpendicularity and avoid any shifting or scalloping issues.
3.3. Installation of the ridge cap
In a steel structure building, the trim and flashing of the roof panels include the ridge cap, sealing plate, and the edges of the gable cornice. These components are connected to the metal sheets using aluminum rivets. Ensuring the trim and flashing are neat, beautiful, and waterproof is essential. Once secured, the seams should be sealed with sealant and smoothed out to ensure evenness. The adhesive must be applied at waterproof points such as flashing boards to ensure complete waterproofing.
3.4. Gutter installation
Steel structure buildings use galvanized steel gutters and welded connections. Before butting the gutter, it is necessary to grind the cutting edge clean and ensure that the gap between the butt welds does not exceed 1mm. After the spot welding confirms that the requirements are met, the complete welding can be carried out. Several sections of gutters can be spliced together on the ground and installed to improve construction efficiency and splicing quality. After installing a quarter of the gutter, drilling a few holes in the middle of the designed downhole position is necessary to avoid water accumulation and affect the construction. After the board is installed in the corresponding place, the drain hole must be opened in time. For this purpose, the cutouts for the formal downhole can be made with a core drill cutter or cutting machine.
3.5. Steel structure building construction for wall panel
During construction, it is essential to use external mobile aluminum tube scaffolding or simple hangers to install wall panels. Paying close attention to horizontal and vertical errors is crucial during the installation process to ensure that the wall panels are level and straight. When installing upper wall panels, it’s essential to place square timber supports beneath the purlins at the bottom end walls and double-check for accuracy. To ensure a proper fit, it’s necessary to install the top and side flashings of the doors, windows, and edges at the junction with the brick wall before installing exterior wall panels. Finally, once the wall panels are in place, install the bottom flashing and edge wrapping of the doors and windows to complete the installation.
3.6 Install doors and windows
To ensure proper installation of doors and windows, it is essential to carefully review the opening size beforehand and make the doors and windows based on the actual measured data. The window frame should be installed first, followed by the window sash in a specific order. In the event of significant gaps between the window frame and opening, it is recommended to use a foaming agent to fill the gaps before gluing. Proper application of glass glue is crucial to ensure optimal sealing and a high-quality appearance. It should be applied evenly and in the correct location.