1、 Project Overview
Construction unit:
Project Name:
Construction unit:
Construction structure:
2、 Construction preparation
2.1 Skill Preparation
1. Before the official start of construction, on-site skill briefing work will be carried out in conjunction with the Planning Institute. After reviewing and positioning the guide points, a construction wire point measurement and control network will be established before the start of construction.
2. Conduct on-site verification of skill documents, familiarize yourself with the content of the documents, and based on construction investigations, promptly submit problems in the planning to the planning unit for resolution. Together, make supplementary construction drawings according to construction needs.
3. Based on the construction site investigation, planning documents, and the requirements of the owner, prepare an implementation construction organization plan, organize and guide the construction.
4. Prepare a special construction plan based on the planning documents.
5. Organize the debris, garbage, etc. within the construction site boundary.
6. Arrange a construction team to enter the site and prepare for construction.
7. Preparation of construction personnel, equipment, and materials, as well as skilled management personnel for this project, with equipment in place to meet construction requirements.
8. Do a good job of pre job training and safety education, communicate with all parties together, contact material sources, and acknowledge the transportation routes.
9. Select and implement construction teams with construction skills and experience that can ensure project quality to undertake various construction missions
2.2 Data preparation
Before leaving the factory, the steel components should be inspected by the manufacturer in accordance with the relevant specifications of the manufacturing specifications and the requirements of the planning diagram, and quality reports and actual error values should be filled out. After the steel components are delivered to the structural installation unit, the structural installation unit will conduct re inspection or spot check based on the quality report of the manufacturing plant and the classification of the components according to their properties
2. Based on the construction drawings, calculate the quantity of each main consumption data (such as welding rods, welding wires, etc.) and connecting parts (such as high-strength bolts, ordinary bolts), make order arrangements, and acknowledge the arrival time
3. After the quantity of temporary support, steel structure assembly platform, scaffolding support, safety protection, and environmental protection equipment required for each construction process is recognized, they will be arranged to enter the factory for manufacturing and installation.
2.3 Primary equipment
In steel structure construction, the main machines commonly used include: AC/DC welding machine, C02 gas shielded welding machine, Bench grinder, wire rope, rigging, Dumpy level, etc.
2.4 Operating conditions
1. The joint review of various planning plans has been completed.
Based on the structural deepening drawings, verify the stress conditions of the components during the steel structure installation, scientifically predict their possible deformation, and take corresponding reasonable technical measures to ensure the smooth operation of the steel structure installation
The review of construction plans for each special type of work has been completed.
The reinforced concrete foundation has been completed and passed the acceptance.
Temporary electricity and water supply for construction are laid in place.
6. Mobilization of labor force
7. The construction equipment and devices have passed the debugging and acceptance.
The incoming acceptance inspection of 8 components is qualified.
3、 Steel structure construction process
3.1 Process flow
Preparation of components, equipment, and personnel → Setting out and inspection of lines (axis and elevation) → Acceptance of embedded bolts and treatment of foundation surface → Component centerline and elevation line → Installation of column and beam center structure → Initial and final tightening of high-strength bolts → Welding of column to column nodes → Spot welding of beams and columns and beam joints → Scattered component (corner support) devices → Device pressed square steel → Welding and bolt connection
3.2 Operation process
1. Steel structure lifting sequence
Steel structure lifting generally requires distinguishing the lifting operation area, and steel structure lifting is carried out together in parallel order according to the distinguished area. After the lifting of a certain area is completed, measurement, calibration, and initial tightening of high-strength bolts are carried out. After several areas are installed, the overall measurement, calibration, final tightening of high-strength bolts, and welding are carried out. After welding and retesting, proceed to the lifting of the next section of the steel column. And according to the actual situation on site, carry out the lifting and partial laying operations of this laminated steel plate.
2 bolt embedment
The accuracy of the column orientation depends on the accuracy of the embedded bolt orientation. Control the elevation error of embedded bolts within+ Within 5mm, the error in positioning the axis should be controlled within ± 2mm.
3 Steel column installation process
Section 1 Steel Column Hoisting
(1) Setting of lifting points
The orientation and number of lifting points are recognized based on the specific conditions of the steel column shape, section, length, and crane function. Generally, steel columns have good elasticity and rigidity, and the lifting point adopts a single point positive lifting. The lifting point is set at the top of the column, with the column body vertical and passing through the center of gravity of the column, making it easy to lift, align, and calibrate. When multiple components are assembled into expanded units on the ground for installation, the lifting point should be accounted for and recognized.
(2) Lifting method
1. In multi-storey and high-rise steel Structural engineering, steel columns are generally lifted by a single machine, and for special or overweight components, double machines can also be used.
2. When lifting, it is necessary to keep the steel column straight and try to reverse and straighten it without dragging the root. During the lifting reversal process, attention should be paid to preventing collisions with other components that have already been lifted, and the sling should have a certain effective height. When lifting the first section of the steel column, a protective sleeve should be added to the embedded anchor bolt to avoid damaging the thread of the anchor bolt when the steel column is in place
3. The first section of the steel column is installed on the column base. Before installing the steel column, the climbing ladder and hanging basket should be hung in the predetermined position of the steel column and firmly bound. After lifting in place, the foundation bolts should be temporarily fixed and the straightness should be checked. The two sides of the steel column are equipped with temporary fixing connecting plates. After the upper section of the steel column is aligned with the center line of the lower section of the steel column top, the connecting plates are temporarily fixed with bolts.
It is necessary to wait for the anchor bolts to be fixed before loosening the sling.
(3) Steel column proofreading
Steel column proofreading requires three tasks: adjusting the elevation of the column base, adjusting the axis of the column base, and proofreading the straightness of the column body. Throughout the entire process, measurement is the primary focus.
1. Column base elevation adjustment
After placing the steel column, use the nuts or elevation adjustment blocks under the column bottom plate to control the elevation of the steel column (because some steel columns are too heavy, bolts and nuts cannot bear their weight, so a height adjustment block - steel plate adjustment elevation - needs to be added under the column bottom plate). The accuracy can be controlled within ± 1mm. The gaps reserved under the column bottom plate can be filled with high-strength, slightly expanded, and non-shortened mortar using the grouting method. When adjusting the elevation of the column base plate using nuts, the strength and stiffness of the anchor bolts should be calculated.
2. Adjustment of column bottom axis in the first section
Alignment method: Without loosening the hook of the crane, align the four points on the column base plate with the control axis of the steel column and slowly lower to the planned elevation direction.
3. Correction of Column Body Straightness in the First Section
Use cable wind rope calibration method. Use two 90 ° Theodolite to straighten. During the calibration process, continuously fine tune the nuts under the column base plate until the calibration is completed. Screw on the two nuts above the column base plate. The cable wind rope is loosened without force, and the column body is in a free state. Then recheck it with a Theodolite. If there is a slight error, repeat the above process until there is no error, and tighten the upper nuts. The nut on the anchor bolt is usually a double nut, which can be welded firmly with the screw after the nut is tightened.
Weld the nut and screw firmly.
4. Adjustment of column top elevation and control of other structural steel column elevations
There are two methods for adjusting the top elevation of columns and controlling the elevation of other structural steel columns: one is to install according to the relative elevation, and the other is to install according to the planned elevation. Generally, relative elevation devices are used. After the steel column is lifted in place, the connecting ear plates connecting the upper and lower steel columns should be fixed with large hexagonal high-strength bolts, but they should not be tightened too tightly. After being lifted by a crane, the crowbar can adjust the gap between the columns. Measure the pre calibrated elevation values of the upper and lower column tops, and after meeting the requirements, use steel wedges and spot welding to limit the drop of the steel column. Considering the welding seam and compression deformation, adjust and control the elevation error within 4mm.
5. Section 2 Steel Column Axis Adjustment
To ensure that the upper and lower columns do not show staggered joints, try to ensure that the centerline of the upper and lower columns overlaps as much as possible. The center line error of the steel column should be adjusted within a range of 3mm each time. If the error is significant, it should be adjusted 2-3 times. The positioning axis of each steel column is absolutely not allowed to use the positioning axis of the next steel column. It should be led from the ground control line to high altitude to ensure that each steel column device is correct and prevent excessive accumulation of errors.
6. Section 2 Steel Column Straightness Calibration
The key to proofreading the straightness of steel columns is to pre check the relevant dimensions of the steel columns. The straightness error at the top of the lower steel column is a comprehensive result of the bottom axis, displacement, welding deformation, sunlight effect, straightness correction, and elastic deformation of the upper steel column. Partial errors can be eliminated by reserving straightness error values. When the reserved value is greater than the accumulated error value of the next column, only the accumulated error value is reserved. Otherwise, the reserved value is reserved, and its direction is opposite to the error direction. Empirical value measurement: The general weld seam shortening value between beams and columns is less than 2mm; The shortening value of the column to column weld seam is generally 3.5mm
4. Steel beam installation process
1. Steel beam device
Steel beam devices are generally lifted using tool type lifting lugs or binding methods. Before installation, the center symbol of the steel beam should be introduced to the end of the steel beam to facilitate temporary positioning according to the positioning axis of the column bracket during lifting.
2. Calibration of steel beams
Proofreading includes elevation adjustment, vertical and horizontal axis adjustment, and straightness adjustment. It is necessary to proofread the steel structure beam after the structure forms a stiffness unit.
3. Elevation adjustment
Use a Dumpy level to stand on the beam or a specially erected platform to measure the elevation of both ends of each beam, weighted average all the data, and calculate a standard value. Calculate the elevation adjustment values of each point based on the standard values.
4. Vertical and horizontal axis calibration
Use a Theodolite to lead the axis to the column, determine the distance between the center line of each beam and the axis, pull a long rope (or use a Theodolite) on the center line of the beam top, and use a chain block to adjust the beam ends one by one. After the longitudinal and transverse axes of the steel beam meet the requirements, recheck the span of the structural beam.
5. Straightness proofreading
Straightness correction: Hang a hammer ball from the upper flange of the beam and measure the horizontal spacing between the wire rope and the upper and lower parts of the beam web. Adjust again based on the inclination of the beam (a ≠ a ') to make a=a.
6. Special rust removal equipment is used for rust removal, and shot rust removal can improve the fatigue strength and corrosion resistance of steel. The hardness of the steel surface is also improved to varying degrees, which is conducive to the adhesion of the paint film without the need for additional coating thickness. The abrasive used for rust removal must comply with quality standards and process requirements, and the relative humidity of the construction environment should not exceed 85%.
The surface of the steel after rust removal must be cleaned with tools such as a brush before proceeding to the next process. If the surface of the steel after rust removal is qualified and has returned to rust before applying primer, it needs to be re rust removed.
7. Paint
After passing the inspection of rust removal on the steel, the first layer of primer is applied on the surface. Generally, after the rust removal is completed, it is stored in the factory and can be coated within 24 hours. If stored outside the factory, the primer should be painted on duty. The paint should be applied in accordance with the planning requirements. After the first coat of primer is dry, the intermediate and top coats should be applied to ensure that the thickness of the coating meets the planning requirements. The paint should be evenly applied without sagging during the brushing process.
4、 Key points of quality acceptance
1 base and support surface
The positioning axis of the building, the positioning axis and elevation of the columns on the foundation, the specifications and orientation of the anchor bolts (anchor bolts), and the fastening of the anchor bolts (anchor bolts) should meet the planning requirements.
The fastening should meet the planning requirements.
2 Devices and proofreading
1. Steel components should comply with planning requirements and regulations. The deformation and coating detachment of steel components caused by transportation, stacking, and lifting should be corrected and repaired.
2. For nodes that require top tightening, the touch surface should not be less than 70% tight, and the maximum edge gap should not be greater than 0.8mm.
3. The surface of the steel structure should be clean, and the primary surface of the structure should be free of scars, mud, and other dirt.
When the steel component is installed on a concrete column, the error between its support center and the positioning axis should not exceed 10mm
5. Steel platforms, ladders, and railing devices in multi-layer and high-rise steel structures should comply with the current national standards of "Fixed Steel Vertical Ladders" (GB4053.1), "Fixed Steel Inclined Ladders" (GB4053.2), "Fixed Protective Rails" (GB4053.3), and "Fixed Steel Platforms" (GB4053.4).
5、 Product protection
1. High strength bolts, studs, welding rods, welding wires, etc. are stacked on shelves in the warehouse, with a maximum of four layers of stacking.
2. The stacking of steel components requires the site to be flat, sturdy, clean, dry, neatly stacked, with sleepers underneath, and to be resistant to deformation and rust.
3. It is not allowed to weld or cut completed components arbitrarily, or stack objects in the air. Welds and node plates that have been completed and inspected as qualified should be immediately sorted out and sealed as required.
When lifting the steel structure into position, it should be slowly lowered and should not collide with the already installed steel structure.
5. Carefully manage the manufactured steel columns, etc., to prevent the unreasonable placement of cushion base points from bending and deformation.
6、 Environmental and occupational health and safety control measures
1 Environmental control measures
1. When welding, steel pipes are used to set up protective railings, and colored cloth is used to surround the railings to prevent the exposure of arc light and welding smoke and dust.
2. Waste generated during and after construction should be recycled and treated.
2 Occupational Health and Safety Measures
1. It is necessary to include the safety skills and measures for operations, as well as the required equipment, in the construction organization plan of the project.
2. Corresponding responsibility systems should be established for unit project construction. Before construction, safety skill education and disclosure should be carried out step by step, and all safety skill measures should be implemented. Construction should not be carried out without implementation.
3. It is necessary to inspect the facilities and equipment used in high-altitude operations before construction, and only after acknowledging their integrity can they be put into use.
4. It is necessary for climbing and suspended operators to hold a certificate and undergo regular professional knowledge assessment and physical examination. It is necessary to wear a safety helmet, fasten a seat belt, wear anti slip shoes, and carry a tool bag when on duty.
5. The high-altitude operation area should have clear signs and be guarded by dedicated personnel. Personnel unrelated to lifting are prohibited from entering. During crane operation, no one is allowed to stand within the rotating radius of the boom.
6. When transporting lifting components, it is prohibited to stand on the components to command and place materials and tools.
7. It is necessary to bind the components firmly, and the lifting point should pass through the center of gravity of the components. When lifting, it should be stable to prevent vibration or oscillation.
8. When working at heights, safety nets need to be installed to prevent accidents caused by personnel, materials, and tools falling or flying out.
9. All objects that may fall from the construction site should be removed or fixed first. The materials used in high-altitude operations should be stacked steadily and not obstruct passage and loading and unloading.
10. When conducting high-altitude operations on rainy and snowy days, it is necessary to take reliable anti slip, cold and freezing measures. Water, ice, frost, and snow should be promptly removed. Before construction, go to the local meteorological department to understand the situation and take measures to prevent typhoons, rain, freezing, cold, and high temperatures. Before and after the snowstorm and typhoon rainstorm, the safety facilities for high-altitude operation shall be checked one by one, and the problems found shall be improved immediately.
11. During the process of structural installation, it is not allowed to operate in the same straight direction when each type of work is engaged in vertical crossing operations. The orientation of the lower level operation needs to be outside the radius of the possible falling range recognized according to the height of the upper level; When the above conditions are not met, a safety protection layer should be set up.
7、 Issues to pay attention to
The quality of pre assembled steel components should meet the planning requirements and quality specifications. The length dimensions of components such as columns, beams, and supports should include deformation values such as welding shortening allowance.
The detection of device errors should be carried out after the structure forms a spatial stiffness unit and is connected and fixed.
When installing 3 devices, it is necessary to control the construction load of the platform flooring, and the construction load must not exceed the bearing capacity of beams, deck slabs, platform flooring, etc.
Only after the installation, welding, and bolting of all components of each column are completed and accepted can the positioning axis of the previous column be measured from the ground.
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