4, the deformation of the component
(1) The component is deformed during transportation, and there is a dead bend or a slow bend, which makes the component unable to be installed.
Cause Analysis:
1) The deformation caused by welding during the production of the component generally exhibits a gentle bend.
2) When the component is to be transported, the support point is unreasonable, such as the underlay is not vertical, or the stacking site is sunk, causing the component to produce a dead bend or a slow deformation.
3) The deformation of the component during transportation due to collision, generally showing a dead bend.
Precaution:
1) When manufacturing components, measures to reduce welding distortion are adopted.
2) In assembly welding, measures such as deformation in the opposite direction are adopted. The assembly sequence should be in accordance with the welding sequence. The assembled tires should be used to set up enough brackets to prevent deformation.
3) Pay attention to the reasonable arrangement of the pads during transportation and transportation.
Solution:
1) The deformation of the member is usually bent by mechanical correction. Use a jack or other tool to correct or supplement with oxyacetylene flame to correct.
2) When the structure is subjected to slow bending deformation, it is corrected by oxyacetylene flame heating.
(2) The full-length distortion of the steel beam members after assembly is more than the allowable value, resulting in poor installation quality of the steel beams.
Cause Analysis:
1) The splicing process is unreasonable.
2) The size of the assembled node does not meet the design requirements.
Solution:
1) Assemble the components to be assembled, and the bottom surface of the components should be leveled to prevent warpage. The assembly workbench shall be at the level of each fulcrum, and welding deformation shall be prevented during the welding. In particular, the final assembly of the beam section or the stairway should be adjusted after the positioning welding. Note that the size of the joint should conform to the design, otherwise the component may be distorted.
2) The components with poor rigidity should be reinforced before turning over the welding. After the components are turned over, they should be leveled, otherwise the components cannot be corrected after welding.
(3) The member is arched, the value is large or less than the design value. When the value of the arching of the component is small, the beam is bent downward after installation; when the arching value is large, the elevation of the extruded surface is likely to exceed the standard.
Cause Analysis:
1) The component dimensions do not meet the design requirements.
2) During the erection process, it is not corrected based on the measured value and the calculated value.
3) Bridges with small spans have a small degree of arching and are ignored during assembly.
Solution:
1) Perform each step of inspection strictly according to the allowable deviation of steel structural members.
2) During the erection process, the rods are installed and the construction of the site joints is completed, and the upper crown is measured, and other adjustments are made during the construction.
3) In the small assembly process, the cumulative deviation should be strictly controlled, and measures should be taken to eliminate the influence of the welding shrinkage.
5, steel structure installation problems
(1) Pre-control measures for the bottom of the steel column Before the steel column is hoisted, the basic elevation should be strictly controlled, the measurement should be accurate, and the basic surface should be carefully leveled according to the measured value; if the secondary grouting method is used, the bottom of the column foot should be watered. Hole (also used as vent hole), use steel pad to flatten the bottom of the steel column, and pre-position the steel plate of the column foot according to the design elevation, and then take secondary grouting.
(2) Pre-control measures for steel column displacement Before pouring concrete foundation, the pre-embedded bolts are clamped according to the design position by using the shaped chuck to prevent displacement when pouring concrete; the reserved holes of the low steel plate should be enlarged, and the hole position is determined. Make a reserved hole.
(3) The vertical deviation of the column is too large. The pre-control measures shall be hoisted in accordance with the calculated hanging point, and the lifting method of two points or more shall be adopted. Temporary fixing shall be carried out during lifting to prevent hoisting deformation; after the column is in place Temporary support should be added in time; vertical deviation should be corrected before fixing.
Second, the conclusion
Only in the process of construction management, strengthen the training and training of technical personnel and workers on standardization standards and operating procedures, effectively prepare for the start of construction, strengthen quality control and supervision and inspection during construction, and actively exert construction, supervision and other aspects. The role of the work of the sub-projects in order to ensure the overall quality of steel structure engineering.
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