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1. Preparation for steel structure installation

(One). Ready to work

1. Construction organization design The construction organization design of the steel structure installation should briefly describe the project overview, full * statistical engineering volume, correct selection of construction equipment and construction methods, rational arrangement of the installation sequence, detailed preparation of major installation technical measures, strict formulation of installation quality standards and Safety standards, careful preparation of project schedules, labor plans, and material supply plans.

 2. Pre-construction inspection The pre-construction inspection includes the acceptance of steel components, the inspection of construction equipment and measuring instruments and the basic re-testing.

(1) Acceptance of steel components The acceptance of steel components shall be in accordance with the requirements of construction drawings and specifications. When the steel components are transported to the site, the manufacturer shall provide the product ex-factory certificate and the following technical documents:

①Design drawings and design modification files;

②Warranty or test report of steel and auxiliary materials;

③ Test data of friction coefficient of high-strength bolts

④ Factory first and second class weld inspection report;

⑤ Inspection report of geometric dimensions of steel members;

⑥ Component list. The installation unit should accept and check the actual condition of the component. If the component is damaged during transportation, it must be repaired by the manufacturer *.

(2) Inspection of construction machinery and measuring instruments Before installation, important lifting machinery, tools, wire ropes and other accessories must be inspected to ensure reliable performance to ensure smooth and safe installation *. During the installation, the measuring instruments must be regularly tested and calibrated by the testing unit designated by the National Bureau of Standards to ensure the accuracy of the measuring standards.

3. Basic retesting. The steel structure is fixed on the steel concrete base (foundation, column top, corbel, etc.). Therefore, the accuracy and strength of the base and its anchor bolts should be retested. The re-testing of the foundation shall determine the horizontal elevation, flatness, deviation of the anchor bolt horizontal position, and the accuracy of anchor bolt embedding. And deliver the retest results and rectification requirements to the base construction unit.

4. Prepare installation plan and component supply plan, and organize construction.

5. Check the steel components: The steel components should have a factory certificate before delivery, check the components according to the drawings before installation, and transport the components to the installation range according to the installation order. Try to put the components on the installation without affecting the installation. Position below to ensure the convenience of installation.

6. Steel column installation: Before lifting, first determine the location of the component lifting point, determine the binding method, and take protective measures when lifting. After lifting the steel column, when the column foot is about 30-40CM away from the anchor bolt, straighten it, align the mounting hole of the column foot with the bolt, and slowly drop the hook into place. After the initial calibration, the vertical deviation is within 20MM. Tighten the bolt and temporarily fix it to release the hook.

7. Steel beam hoisting: Steel beam hoisting is carried out after the column review is completed. Two-point symmetrical lashing is used to hoist the steel beam in place for installation. After the steel beam is hoisted, it is slowly in position when it is 100mm away from the column reference surface. After the steel beam is hoisted in place, adjust and correct it, and then fix the connection. When the steel beam is hoisted, it is corrected with the theodolite and any deviation is corrected at any time.

8. Wall purlin installation: The purlin has a smaller cross-section and is lighter in weight. It is hoisted by one hook or multiple pieces. The correction of purlins is mainly the pitch size and its straightness. The distance check sample rod moves back and forth between the purlin rods. If there is an error, loosen or tighten the bolts for correction. Straightness is checked and corrected with cable and steel ruler, and then fixed with bolts.

9. Installation and calibration

①. Steel column correction: The verticality correction of the steel column is checked by theodolite or suspension hammer. When there is a deviation, the jack is used for correction. The elevation correction uses a jack to raise the base a little, and then the pad thickness is increased or decreased. The anchor bolts shall be fixed by pouring fine stone concrete under the bottom plate of the column foot after the steel column is corrected completely.

②. Steel beam correction: The measurement and correction of the axis and verticality of the steel beam. The correction is carried out with a jack, and it is fixed immediately after the correction.

(two). Wall profile color board installation

1. Preparation before construction

① Prior to the installation and installation of profiled steel sheet enclosures, order the corresponding construction drawings, and organize the design according to the design documents and provide technical training and safety explanations to the construction personnel.

② Check the specifications and quantity of various materials in detail according to the documents. The damaged profiled steel plates and flooded plates should be promptly restored and replaced.

③, all kinds of construction equipment should be complete and can operate normally.

④ 、 Review the installation accuracy of the steel components related to the installation of profiled steel plates, clean the purlins and splashes of the welds, and apply anti-rust paint for anti-corrosion treatment.

2. Construction process of pressure-type color board: wall board installation starts from one end according to the purlin position, * between the board and the board must be bitten, and then fixed with screws, the wall board joints are waterproof. When installing the profiled steel plate, adjust its position while laying and fix it.

(3). Floor pressure plate installation

Before the construction and installation of the floor pressure-bearing plate, draw the corresponding arrangement drawing and carry out the construction according to the drawing. The profiled steel plate is laid along one end of the floor, and its position is adjusted while laying, and fixed. When there is a hole, first install the profiled steel plate, and then cut the hole size according to the actual hole position.

Second, the stability problem in the installation of steel structures The problem of single member stability and overall structural stability

1. Component single component stability The problem of component single component stability refers to the bending, twisting, and instability of a component during stacking, lifting, hoisting, and positioning on the construction site. Therefore, this problem should be considered for thin and large components.

2. The overall stability of the structure The overall stability of the structure means that the support system has not been formed during the lifting process, and the structure will bear certain loads (including its own weight). Therefore, when formulating the hoisting sequence, this factor must be fully taken into account to ensure that the structure of each step in the hoisting process is stable. If there is a problem, measures such as temporary cable wind can be added to solve it.

Third, the steel structure installation and connection problems

The on-site connection of the steel structure is mainly ordinary bolt connection, strong bolt connection and safe connection.

1. Ordinary bolt connection. Ordinary bolts are mainly used for the nodes under bending and tension. The bolts are mainly tensioned. After adding appropriate prestress, it is also widely used in shear connection of transmission tower and other structures. After the ordinary bolts are tightened, the exposed wire buckle must be no less than 2 to 3 buckles. Common bolts should have anti-loosening measures, such as double nuts or fastening nuts to prevent loosening. If the bolt hole displacement is small, the reamer or file can be used to repair the hole, and the hole can not be repaired by gas cutting.

2. The strongest bolt connection. The strongest bolt connection is generally used in important structures that directly bear the dynamic load. Its main feature is to transmit the shear force through the friction of the contact surface. Therefore, when installing the strongest bolts, the method and roughness of the friction surface must be processed according to the specifications. Secondly, the friction coefficient and torque coefficient tests shall be carried out. During the installation, the initial and final tightening torques of the bolts shall be determined.

3. Construction site * connection, inspection of construction site * connection with factory * connection

(1) Avoid site * connection in design

(2) Prevent the impact of bad climate environment (rainy weather, windy, low temperature climate) on construction

(3) Reduce the disadvantageous * connection station (the on-site operation structure cannot be rotated, it can only be welded on the back, and even the connection of the personnel is difficult). The problems that should be paid attention to during the lifting of the steel structure. When installing columns and beams, Mainly check whether the shim under the bottom of the column is solid and flat, whether the column is vertical and whether there is displacement, and the verticality and lateral bending height of the primary and secondary beams. When the steel structure is installed to form a space fixing unit, and the acceptance is passed, the construction unit is required to promptly pour the space of the column floor and the top surface of the foundation with expanded concrete, and to check the verticality and overall plane bending of the main structure of the steel structure. Wait

4. Preparation before hoisting.

When the steel column is manufactured, the design axis is marked on the column foot plate, and the cross control line is popped on the top cover plate, which is used for controlling the axis and verticality when lifting and using bolts to control the quality of the installation. The bolt connection in steel structure engineering generally uses ordinary bolts and high-strength bolts. For ordinary bolt connection, one end of each bolt shall not be filled with more than two gaskets, and the bolt hole shall not be expanded by gas cutting. After the bolt is tightened, the exposed thread shall not be less than 2 pitches; for the * strong bolt * point, control the friction of the bolt connection (sand blasting) Treatment), the anti-slip coefficient of the friction surface, the order of the bolt connection vice, the torque values of the initial, final, and screwing, the exposed value of the bolt thread, and the damage and deformation of the node plate surface. During the installation process, the contact surface of the board should be flat, the contact surface * must be greater than 75%, the edge gap should not be greater than 0.8 mm, the * strong bolts should be penetrated, and must not be knocked or enlarged; * the strong bolts should not be used as temporary installation bolts The bolt tightening should be carried out in one direction. The bolts installed every day should be finalized. After the final tightening, they should be inspected one by one. The under-tightening or over-tightening should be repaired or replaced.

Important quality control points of steel structure engineering

The pre-embedment of anchor bolts directly affects the installation quality of the steel structure. The position, verticality, length and elevation of anchor bolts (groups) are well controlled. For reducing the hole expansion and adjusting the workload (even To avoid rework), it is of great significance to improve the quality of structural installation. The pre-embedded method of anchor bolts can be the direct pre-embedded method or the reserved hole method.

 V. Construction measures of steel structure project in winter and rainy season

(1) Winter construction measures

1. The construction and installation of steel structure in winter construction shall be carried out strictly according to relevant winter construction regulations of steel structure.

2. When steel components are manufactured at positive temperature and installed at negative temperature, the shrinkage of the component should be considered according to the difference in ambient temperature, and technical measures to adjust deviations during construction should be taken.

3. Participate in the construction of negative temperature steel structure

The electric welder should go through the negative temperature * connection process training, pass the examination, and obtain the corresponding certificate.

4. Steel and related connection materials used at negative temperatures must be accompanied by quality certificates, and their performance meets the requirements of design and product standards.

5. The electrode used under negative temperature should not be exposed for more than 2 hours, re-bake after 2 hours, and the number of electrode baking should not exceed 3 times.

6. Flux should be baked according to regulations before use so that its water content does not exceed 0.1%.

7. The strongest bolts used under negative temperature must have product certification, and re-test the torque coefficient and axial force under negative temperature.

8. Water-based paints must not be used for paints used on steel structures at negative temperatures.

9. When the component is blanked, the shrinkage allowance should be reserved. The welding shrinkage and compression deformation should be coordinated with the shrinkage deformation of the steel at negative temperature.

10. When assembling the components, expand the assembly from the inside out in the order specified by the process, and make an experiment to determine the weld shrinkage value that needs to be reserved during the assembly at negative temperature.

 11. When assembling the components, clear the rust, burrs, soil, oil, ice and snow and other debris left in the 50mm of the joint, keep the joint dry and no residual moisture.

12. Multi-layer welding should be used for welding steel plates above 9mm under negative temperature. The welding seam is welded layer by layer from bottom to top. Each welding seam is welded once. If the welding is interrupted, clean it before welding again ** trap. It is strictly forbidden to start the arc on the * connected base metal.

13. When the steel structure is installed on site, if it encounters snow or wind speed is above 6m / s, a protective shed shall be erected.

14. Welding of unqualified welds is eliminated, and welding is carried out in accordance with the provisions of the steel structure * connection process at negative temperature.

15. When the ambient temperature is lower than 0 ℃, conduct the brushing process test before applying the anti-corrosion coating. During the coating, the rust, oil stains, burrs, etc. on the surface of the component must be cleaned, and the surface should be kept dry. Do not paint in snow or when there is thin ice on the components.

16. Take anti-skid measures when transporting and stacking steel structures in winter. The component stacking site is flat and solid without puddles, and the ground is free of icing. When stacking components of the same type, the components should be kept horizontal, and the horns should be placed on the same vertical line to prevent the components from slipping.

17. Re-inspect the quality of the steel structure according to the requirements under negative temperature before installation, and repair and correct the components that have been deformed during the manufacture of the leak detection and transportation stacking.

18. When using steel cables to lift steel components, non-slip spacers should be added, the node plates that are lifted at the same time as the components, the fixtures and other objects required by the installer should be tied firmly with ropes.

19. According to the temperature conditions, a chart of the installation sequence of steel components is compiled, and the installation is strictly carried out in the prescribed order during construction.

20. Welding process of steel structure installation is prepared, and the two ends of a member shall not be welded at the same time.

twenty one. Before installation, clean the surface of the components from ice, snow and dew, but do not damage the coating.

twenty two. The columns and main beams installed at negative temperature are immediately corrected, and the correct position is immediately and permanently fixed. The components installed on the day should form a stable space system.

23. During the installation of high-strength bolt joints, there must be no snow or icing on the friction surface of the components, or contact with dirt, oil, dirt or other stolen goods.

24. In addition to complying with the requirements of "Code for Construction and Acceptance of Steel Structure Engineering" (GB50250-95), the installation quality of steel structures under negative temperature should also be checked and accepted according to the design requirements.

(2) Construction measures during the rainy season

1. When constructing on rainy days, it is advisable to set up a temporary protective shed, and the rain shall not fall on the hot welding seam. If the welding part is relatively wet, * must clean it with a dry cloth and dry it with an oxyacetylene flame before * connecting to keep the seam Dry and no residual moisture.

2. If there is water on the component during lifting, it should be cleaned before installation, but the coating should not be damaged. When installing the strong bolt joint, the friction surface of the component should be clean, there should be no water drops, and it should not be exposed to rain or contact with mud And oily dirt.

3. The rainy weather component can not be painted.

4. Roof insulation can not be carried out on rainy days and strong winds above level 5.

5. Due to the relatively humid air in rainy days, the electrode should be stored in a moisture-proof and baked. The repeated baking times of the same electrode should not exceed two times, and the management personnel should make baking records in time.

 6. In case of strong winds, large components such as columns, main beams and supports should be corrected immediately. After correcting the position, they should be fixed immediately to prevent unilateral instability. The components installed on the same day should form a spatial stability system