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Erection of steel frames in factory construction includes many important stages. At each stage, there are strict processes to ensure the best quality and safety for customers. Below article, FACTORY Will introduce details about erection process Steel Buildings as well as the rules to be followed when installing.
Erection is the final step in the pre-engineered steel building construction process. In this step, all components, steel frames and materials will be transported from the factory to the construction site for erection.
1. Construction process of pre-engineered steel buildings
To ensure the safety as well as the quality of the work, the pre-engineered steel building erection process is carried out in the following sequence of steps:
Step 1: Planning and preparation at the construction site
- Site survey: Inspect the construction road to ensure that the cargo truck and crane can operate.
- Check the location to gather materials and goods, it is necessary to ensure that materials and goods must be gathered in designated areas so that it is most convenient for construction.
- Based on the ground conditions to make a construction plan, notify the factory of this plan so that the factory can make a plan for production and supply of goods on that basis. It is necessary to ensure that the delivery schedule of goods is synchronized and does not affect the progress of other departments.
- Conduct inspection and survey of electrical connection locations before construction. It is necessary to ensure that these power supplies lead to the construction area in the safest way.
- Organize occupational safety training for workers.
- Inspect construction equipment, all tools, equipment, and machinery to make sure all equipment meets normal working requirements.
Step 2: Check and survey anchor bolt position
- Before installing the steel structure, it is necessary to survey the position and height of the pre-installed anchor bolts (This is called the completion step of locating anchor bolts).
- Positioning landmarks and elevations must be based on the required design elevation.
- All survey equipment must be properly calibrated.
- Anchor bolts must be prevented from moving horizontally, vertically and vertically throughout the entire process from installation until after concrete is poured.
- The tolerances are as shown in the following table:
|Deviation of center distance of 2 bolts in 1 cluster||5mm|
|Deviation of center distance of 2 bolts next to each other||10mm|
|Altitude difference between the tops of anchor bolts||15mm|
Step 3: Delivery of materials at the construction site
- All components are pre-manufactured at the factory, which is a feature of pre-engineered steel buildings. During the construction process, if a member is wrong or missing a component, it will directly affect the construction progress on the site.
- A delivery note is required and the receiving party and the delivery party sign for full certification. The process of receiving necessary materials must match each material with the delivery note, and confirm the number of goods received on the delivery note, and make a preliminary assessment of the quality of the goods before deciding whether to accept or not. Ensure adequate materials and components to ensure the continuous construction and erection process.
Step 4: Preserving materials on the construction site
- Choose a solid, compacted and dry area as a temporary storage for auxiliary materials.
- Materials are stacked at positions corresponding to the part of the work or construction area, and should be next to the position where the crane will stand up for installation. This will facilitate sorting and delivery during the construction process.
- Materials must be stored away from dust, grease and other impurities; as well as to protect against water contamination from motor vehicles on the construction site.
- Do not walk or step on materials and components.
- All bolts, nuts, screws, small plates and accessories must be properly packaged and labeled.
Step 5: Installation at the construction site
- Depending on the nature of the work, it can be constructed by different methods, depending on a number of main factors as follows:
– Type of structure (such as: small-span house, large-span house, low-rise building, high-rise building, I-beam structure, hollow belly structure, etc.)
– Type of equipment available (such as: cranes, forklifts, towing winches, hand lifts etc.)
– Existing construction site conditions
– Experience of each roofing team
- The order/method of construction must be studied and planned, so that construction can be carried out safely, economically and effectively.
- The process of specific construction measures for each project must be discussed in advance, detailing the requirements before starting construction. Depending on the characteristics of each project, different construction methods will be applied
Step 6: Monitoring plan and Checking acceptance
a. Acceptance testing
Inspection and acceptance of steel structure erection is carried out according to the following steps:
- Check each item before moving (internal acceptance)
- Checking and acceptance of completed items (representative of TVGS for acceptance)
- Checking and acceptance of completed project handover (full parties involved)
b. Monitoring and inspection plan
Check the lock time
- After installing the first 2 trusses of the hard-locked space, the Construction Supervisor will stop the work and notify the Chief of Staff to check and sign through the internal inspection step before the Construction Supervisor inspects.
- The project manager must check and sign the lock on the condition of the lock, record it to ensure that the building is not improperly moved or collapsed during the installation process.
Check bolt tightening force
- All 100% structural bolts must be checked by the captain for the required tightening force and marked. The testing device is using a verified torque wrench.
- Bolt tightening as well as final tightening of bolts need to be carried out from the hardest part of the connection to the edge of the connection. Should avoid re-tightening the bolt (which has already been tightened before):
– Exception, when re-tensioning must be performed, it is only allowed to be performed once where the bolt is still in the same bolt hole (where it was previously tightened) and in the same direction. long arm or 1 type of tightening gun.
– It is not allowed to re-tighten galvanized bolts.
– Under no circumstances is it allowed to use fully tightened bolts for reuse in another place.
– The tightening or re-tensioning of bolts (which have been tightened) loosened when tightening the adjacent bolts is not considered a case of re-tensioning. The final tensioning of the bolts is carried out only after the azimuth and elevation alignment is satisfactory.
- Bolt tightening order:
The figures above show the order in which bolts are allowed to be tightened at any connection.
- The tightening is done through 2 rounds, the second round to ensure all bolts are tightened. Moment allows to tighten bolts and check. In completed connections, all bolts must reach the specified minimum tension
- Another method to check bolt tightening force: Use a torque wrench with a force range corresponding to the allowable tightening torque of the bolt.
- Verification and official report on the azimuth of 1 main truss frame and 2 gable truss frames. If feasible, alignment should be made immediately after the partial installation of the frame structure. Do not make permanent connections between components, until there is an appropriate part of the house frame system that has been aligned in azimuth, elevation, and verticality, as well as temporarily connected so that these members do not move during construction and alignment of the rest of the frame system.
- Internal testing must be done first. This acceptance is to ensure quality requirements, as well as to plan for alignment, cleaning and buffing.
- Applied standard:
– TCXD 170-2007: Steel structure – Processing – assembly – acceptance – Technical requirements
– TCVN 5593: 2012 Construction work
2. Construction equipment
a. Mobile machinery equipment
- Mobile machinery includes delivery trucks, tank cranes, hoists, etc.
- Only mobile machinery and equipment that have passed the inspection of skilled operators are allowed to enter the construction site.
- Where there is a risk that mobile machinery may come into contact with electricity, all electrical conductors must be fenced or flagged. Power lines that pose a risk of an accident must be disconnected, or made safe, before commencing any work.
- No machinery should operate directly on the power line.
- Never operate machinery located less than 220m from a power source >4,5 Volt.
- Avoid walking near or directly under an object being lifted. All hoisted loads must have a tagline to steer the load.
- Before hoisting anything, the vertical position of the crane and the lowering position of the crane in the construction area must be clearly determined. Work must be carried out to ensure occupational safety and analysis of possible hazards (based on the Occupational Safety Procedure in Site Installation).
- During all stages of construction, damage to the structural finish should be avoided or minimized by using nylon ropes or belts with protective padding in places of direct contact with the steel structure; or by using shackles piercing the bolt holes to lift.
b. Crane ropes and slings
- There must be a careful inspection of crane cables and slings. Damaged cables and slings must be cut off and destroyed immediately.
- When carrying out hoisting, avoid using the crane rope arbitrarily. Crane ropes should be protected by lining sharp corners. Absolutely do not jerk suddenly when hoisting, because the sudden jerk will increase the load 3 times normal, dangerous for the crane rope. When not in use, the crane rope should be neatly connected. Never let the crane rope be overloaded.
c. Construction Scaffolding
- There must be a plan to use and install construction scaffolding so that it does not obstruct the movement of the crane truck and the reach of the boom, as well as does not cause difficulties for construction operations.
- Always place scaffolding on hard ground or plank, minimum size 200 x 200 mm. Separate scaffolding must be fastened to the fixed structure with a minimum clearance of 1,5m. Each upper scaffolding floor needs to be fastened to the lower floor by steel wire or scaffolding pipe, so as to ensure safety.
d. Hand tools
- All hand tools must have a lanyard to keep them from falling during work.
- Equipment must be used for its intended purpose. Never use a hand-held device for work other than its intended purpose. Never use temporary substitutes.
- Definitely never use damaged tools, machinery and equipment with frayed or faulty windings or without protective caps.
3. Steel Structure erection method for a typical steel building frame
[STEP 1] INSTALL THE HARD LOCKED Column
a. Install the first column
- The first column is required to have an anchor cable to anchor the column after installation.
- Cable anchor position can drive piles or clusters of anchor bolts nearby
b. Align verticality, position, pitch
- Bring the forklift to the column position
- Tighten and tighten the anchor bolt, align the column base as required
- Equipment: plumb line, theodolite and tape measure
- Tighten all anchor bolts with a wrench with a force of xi
c. Install the next column and brace the column or wall purlin between the columns
- Straps/purlins must be installed in quick succession to secure the column.
- The bolt tightening force is just enough to keep it stable.
[STEP 2] INSTALLING THE FIRST Glue Beam
a. Combination of connecting trusses on the ground surface
- The rafter segments are assembled under the ground surface according to the mounting diagram
- The cable is connected to the member at 2 points about ¼ of the length from the end of the member, the side of the purlin/rib is stiffened. However, the head outside the suspension point must be calculated to avoid torsion of the member due to self-loading. The first part outside the suspension point must not exceed 1/3 of the length of the member bar. Lifting angle also needs to be calculated to avoid torsion due to longitudinal force when hoisting. For safety, it is recommended to use more than 2 points of crane cable connection
- When combining, it is recommended to use wooden bars with a thickness of 50mm to support the structure
- High strength bolt tightening device: Torque wrench, recommended minimum torque torque (see Table of Torque Torque)
- Temporary bracing and bracing against purlins to the rafter
- Use sandpaper and cleaning cloth to clean components. Paint mile scratched with a paint roller
- Lift 1 or 2 times to check the balance of the crane cable
b. Install 1 truss on the pole
- The first semi truss crane is placed on top of 2 consecutive columns, stabilized by a crane
- Manipulators will stand on forklifts or ladders, pierce and tighten flange bolts connecting columns and truss beams to a tight enough state.
- Use a cable to temporarily brace the rafter beam, placed at a distance of about 6m, to hold this first semi-rafter firmly to the column bolts with V iron bowls..
- Lightly release the crane cable to see if the rafter is stable, before releasing the crane cable completely.
c. Repeat step 1 and step 2 for the remaining rafters, forming a complete truss frame
[ STEP 3 ] INSTALLATION OF THE SECOND FRAME
a. Do the same step 2 for the 2 half trusses of the second truss frame
- Only use temporary bracing on both sides in the middle of each truss, braced on the foot bolts with iron bowls
b. Install roof top braces/temporary purlins immediately to keep the trusses in place
[ STEP 4] COMPLETE 100% COURSE
- Install all truss braces, purlins, anti-purlins – 100% of the quantity
- Install all permanent cross-bracing cables of columns and truss beams for the lock space.
- Leave these braces in a loose state (unstretched).
- Adjust the truss frame:
– Use temporary braces to align the frame
– Fully tighten the permanent braces.
– Sign the inspection record through the hard lock booth
[ STEP 5 ] INSTALLATION OF ALL THE FRAME AND POINT
- Install all side and center columns on subsequent axes
- Adjust column verticality, position and height
- Do the same [step 3] and [step 4] for all rafter frames and roof purlins
- For structures with a column in the middle, it is not allowed to install one side of the rafter and then the other side. Doing so will change the design calculation scheme of the frame, causing imbalance of the frame, which can lead to the collapse of the structure in bad weather.
[ STEP 6 ] INSTALL THE END GALLER
- Install the final truss frame in the same sequence as the above steps.
- Install all rafter braces, purlins, purlin struts, purlins for the remaining 2 gables with 100% of the remaining quantity.
- Install all permanent cross braces of columns and trusses for the final lock.
- Leave these braces in a loose state (unstretched).
- Align truss beams
- Fully tighten the permanent braces.
- Remove all temporary bracing of the building.
- Inspect and verify all connections, ensuring all bolts are fitted. All high-strength bolts (structural bolts) must be tightened to the required tension. Bolts after tightening must be marked to avoid damage.
- Check the entire structural frame one last time: correct plane azimuth and verticality
- Make a test record.
[ STEP 7] INSTALLING THE ROOF
- Steel cranes on the roof using corrugated iron racks
- Use the wind rope to guide
- Crane corrugated iron according to each file in each time step, the position is placed close to the steel truss frame
- Stacks of corrugated iron must be fastened with 3mm steel wire at least 3 positions and have measures to prevent drift.
- When enough corrugated iron is pulled, the installation team will start roofing work.
[STEP 8 ] INSTALLATION OF RELING
- Install safety cable system on the roof
- Preparing electrical system for construction
- Install the first roofing sheet:
– Position the first corrugated iron sheet, align so that the protrusion into the gutter edge is even and from 100-150mm.
– Shoot the screw to position the first sheet of corrugated iron.
- Match the next sheet to match the wave with the first word
- Check regularly that the corrugated iron sheets are aligned with the gutter edge.
- Screw 100% of positions according to each type of corrugated iron.
- Apply 100% silicone glue to the screw heads
- Regularly use a broom to clean iron filings and dirt
- If the roof uses insulation, this insulation will be applied by the strip first and then put the roof sheet on later. Insulation must be stretched and flat to ensure aesthetics and quality.
[ STEP 9 ] INSTALLATION OF FLOORING – Gutters – Gutters and ACCESSORIES
- Prepare the ladder of preparedness measures
- Use pulleys, ropes to pull each sheet of corrugated iron into position
- Workers manipulating positioning screws standing on a ladder
- The corrugated board must first be straightened perpendicularly before screwing.
- Subsequent corrugated iron sheets must be regularly checked for alignment to avoid running corrugated iron.
- The sheet is cleaned before installation
- Install gutters, pipes, frills, etc.
Some pictures of Hai Long's steel structure construction and erection