Common Problems and Solutions in Steel Structure Construction-2

4.the deformation of components

(1) Deformation of components in transit, appear dead or bent, resulting in the component can not be installed.

Cause Analysis:

1) The components produced due to the deformation of the welding, the general slow rendering.

2) If the component is going to be transported, the supporting point is unreasonable. For example, the upper and lower padding are not vertical, or the sinking occurs on the stacking site, causing the components to die or bend slowly.

3) Deformation due to collisions during transportation of components, generally showing dead curves.

Precaution:

1) When the components are made, the measures to reduce the welding deformation are adopted.

2) Assembly welding, the use of deformation and other measures in the reverse direction, the assembly sequence should be subject to the welding sequence, the use of assembly of the tire, set up enough brackets to prevent deformation.

3) To be shipped and transported, pay attention to the reasonable allocation of pad.

Solution:

1) Structural dead bending deformation, the general use of mechanical correction method. That is, with jack or other tools to correct or supplemented with oxyacetylene flame roasted after correction.

2) When the structure is bent and deformed, take oxyacetylene flame to heat and correct.

(2) The total length of the steel beam after assembling distortion exceeds the allowable value, resulting in the poor quality of the steel beam installation.

Cause Analysis:

1) stitching process is unreasonable.

2) Assembly node size does not meet the design requirements.

Solution:

1) assembly components to be assembled assembly workbench, as the welding components to be leveling the bottom to prevent warping. Assembly table should be the level of the fulcrum, welding to prevent welding deformation. In particular, the final assembly of beam sections or stairways should be adjusted after positioning welding deformation, pay attention to node size to meet the design, otherwise easily lead to component distortion.

2) The parts with poor rigidity are to be reinforced before turning over, and the leveling should be performed after turning over the components, otherwise the components can not be corrected after welding.

(3) Arch components, the value of dry or less than the design value. Component arching numerical hours, the installation of the beam under the flexible; arching numerical, easy to produce extrusion surface elevation exceeded.

Cause Analysis:

1) Component size does not meet the design requirements.

2) erection process, not based on the measured value and the discrepancy of the calculated value of the amendment.

3) A bridge with a small span, with a smaller camber, neglected when assembled.

Solution:

1) strictly in accordance with the production of steel structure components to allow deviation test step.

2) In the erection process, the rod is installed and completed, and the construction site joints are completed, the crown camber measurement, and other adjustments in the construction.

3) In the small assembly process, the cumulative deviation should be strictly controlled, pay attention to take measures to eliminate the impact of welding shrinkage.

 

5. steel installation problems

(1) pre-steel column foot gap pre-control measures Before lifting the steel column, the base elevation should be strictly controlled, accurate measurement, and according to the measured value of the underlying surface carefully leveled; such as the use of secondary grouting method, Hole (also serves as a vent), the use of steel pad flat bottom uneven steel column, and pre-designed height of the column foot bearing steel plate, and then take the second grouting.

 

(2) Pre-control measures of steel column displacement Before pouring concrete foundation, the fixing bolts shall be used to fix the embedded bolts according to the designed position so as to prevent the displacement when concrete is poured. The reserved holes of low steel plate should be enlarged to determine the positions of the holes Make reserved hole again.

 

(3) The column vertical deviation is too large Pre-control measures should be hoisting steel columns in accordance with the calculation of the lifting position, and must be used more than two lifting methods, lifting should be temporarily fixed to prevent lifting deformation; column in place Temporary support should be added in time; the vertical deviation should be fixed before it is fixed.

 

Second, the conclusion

Only in the course of construction management, we should strengthen training and study of technical personnel and workers on normative standards and operating procedures, earnestly prepare for starting construction, strengthen quality control and supervision in the construction process, and give full play to all aspects of construction and supervision The role of sub-project to do a good job acceptance of the work in order to ensure the overall quality of steel structure works.