Steel structure for its own merits, bridges, industrial plants, such as modern high-rise building construction has been widely used. In a large number of construction projects, steel works also reveal a lot of quality problems. This article aimed at Liaoning in recent years in the steel structure of the main inspection and final acceptance of frequently asked questions and talk about some reform measures.
First, construction steel structure in the course of some of the problems and solutions
1, the production of components of the production problems
Door-plate steel used in the pieces of thin, the thinnest available to 4 mm. Under the multi-sheet material should be the preferred way to avoid cut by flame cutting. Used as flame cutting edge board will have a great wave of deformation. At present, most of the welding of the H-shaped steel manufacturers are using semi-automatic submerged arc welding or brazing. Control should not occur if welding deformation, so that the bending or distorting components
2, installation of foot-chu
(1) embedded parts (Anchor) is the problem: the overall layout or migration; elevation error; Sikou unprotected. As a direct result of plate steel bolt hole wrong place, resulting in the length of Sikou enough
Measures: Steel construction co-construction and construction units work together to complete embedded parts, before ramming the concrete pouring. Review must be related to size and firmly fixed
(2) Anchor is not vertical: the framework of the soles of the feet-chu-chu, the level of difference, not the vertical reinforcement, the basis of the level of Anchor Construction embedded after the error too. After the installation of the pole is not a straight line, Dongdaoxiwai, so it is difficult to see the appearance of housing, the installation of steel columns to bring the error, and this has affected our structure, construction inspection do not meet regulatory requirements.
Measures: Anchor installation should adhere to the first floor with the lower part of leveling readjustment bolt, and then contracted with the second mortar grouting to fill it, this method of construction abroad. Therefore, Anchor Construction, that can be fixed, such as angle steel or steel reinforcement. Welded into a cage-like, sound support, or to take other effective measures to avoid watering when the concrete foundation for a shift Anchor
(3) the problem is to connect Anchor: Anchor foot column is not tightened, not with the bottom plate welding; not part of the open 2 to 3 Sikou of Anchor
Measure: To be taken by welding nuts and bolts; chemical in the external Anchor should be thickened to deal with fire retardant coating and insulation to prevent the fire affected the performance anchor; should additionally on the basis of settlement data
3, connection problem
(1) high-strength bolts to connect
1) bolt surface equipment do not meet the requirements, resulting in a bad bolt installation, or the extent of the fastening bolts do not meet design requirements
Analysis: ① there are floating on the surface rust, impurities such as oil pollution, there are glitches Kongbi bolts, welding, and other tumors. ② the installation of a bolt, although there are still treated defects
Solution: ① high-strength bolts floating on the surface rust, oil pollution and bolts Kongbi problems should be cleared one by one. Use must be approved by the former anti-rust treatment, so that the bolt used in the assembly, must not use the formal assembly. Bolt and custody of the person should be paid. ② assembly to deal with surface construction should take into account the order of the installation, to prevent duplication, and try to deal with before hoisting
2) bolts Sikou injury, can not be free screw screwed nut, bolt the impact of the assembly. Analysis: Sikou severe corrosion
Solution: ① the use of pre-bolts should be selected after the pre-equipped with cleaning rust. ② Sikou injury did not bolt temporary use of bolts, forced into Luo Kong is strictly prohibited. ③ pre-bolts of matching sets of components should be stored, and when not to use the swap
(2) on-site welding phenomenon: it is difficult to ensure quality; design requirements of a full-penetration, the secondary did not use ultrasonic testing of welds; the main floor beams and columns are not welding facilities; did not use the plate arc welding facilities.
Solution: Shi welding steel, welding rod on the certificate of inspection, according to the choice of design requirements including welding, according to the manual procedures and require the use of welding, weld cracks on the surface of any kind, welding tumors, primary and secondary weld May not have pores, slag, crack Crater, a bite welds may not have the edge, under the age of welding defects, such as, primary and secondary weld required to carry out non-destructive testing, provided the site to inspect welds and welder's Seal . Failure of the weld are not allowed to deal with, the process for amending the blanks later, the same site of the weld should not be more than twice the number of returns.
4, the deformation of the components (1) in the transport component deformation occurred, the dead appeared bend or turn ease, resulting in components can not be installed
Analysis: 1) the production of components due to welding deformation resulting from the general ease a bend. 2) components for shipment, the branch point cushion unreasonable, such as stow-wood not up and down or vertical stacking sites, such as subsidence occurred, so that components have died or bending deformation relief. 3) The transport component of deformation arising as a result of the collision, a general turn to die
Preventive measures: 1) the production of components, reducing the use of welding deformation. 2) The welding assembly, the use of deformation in the opposite direction, and other measures, the order of assembly should be subject to the order of welding, assembly of the use of a child, set up enough support to prevent deformation. 3) to be transported and transport, pay attention to point rational allocation pad
Solution: 1) member to die bending deformation, the general use of mechanical correction method of governance. That is, with jack and other tools to correct or by oxyacetylene flame grilled after the correction. 2) The structure of relief when bending deformation, to take corrective oxyacetylene flame heating.
(2) steel components assembled after a total length of more than allow the value of distortion, caused by bad quality of the installation of the steel beam
Analysis: 1) unreasonable splicing technology. 2) assembling nodes do not meet design requirements for size
Solution: 1) to set up assembly components assembled table, as when soldering components to leveling the bottom to prevent warping. Assembling the table should be the fulcrum level of welding in welding to prevent distortion. In particular the beam or ladder in the last assembly, it is necessary to adjust the position after the welding deformation, the attention of the node size to meet the design, or easily give rise to distortion components. 2) own less rigid elements, stand up before the welding facilities to be reinforced, after the component should also stand up for leveling, or post-solder components can not be corrected
(3) component arch camber, big or numerical value is less than the design. Component values arch camber hours to install Houliang under torsion; arch camber great value, easy to squeeze excessive surface elevation.
Analysis: 1) The size of components do not meet design requirements. 2) to set up the process, not based on the measured and calculated values different from the amendment. 3) small-span bridge, arch camber smaller degree, when the assembly ignored
Solution: 1) strictly according to Deviation allow the production of steel components for the step-by-step test. 2) to set up in the process, the pole and finished loading, as well as the joint construction site after the arch on both measurement and construction of other adjustments. 3) in the process of assembling a small, should strictly control the total of bias, pay attention to measures to eliminate welding contraction of the volume
5, the installation of steel structures
(1) foot at the end of column space have pre-control measures before hoisting steel column should be strictly controlled basis of elevation, accurate measurement, and its measurement on the basis of careful leveling the surface; such as the use of the second grouting, Column in the watering hole to open the soles of the feet (double vent), the use of steel plate at the bottom of the column will be uneven Department-pad and pre-designed foot elevation settle column bearing plate, and then take the second grouting. 2) pre-column shift control measures on the basis of concrete poured before the chuck stereotype application will be embedded location of the stuck bolt designed to prevent the casting of concrete when displacement; column hole should be reserved for low-plate-like zoom, and then determine the hole - Set aside for the hole. (3) vertical column deviation is too large steel column pre-control measures should be calculated at lifting hanging in place, and must be used for more than 2:00 of the lifting methods, should be Hoisting temporary fixed to prevent the lifting deformation; in place after the column Should provide temporary support in a timely manner; on the
vertical deviation should be fixed before the amendment
Second, the conclusion
Only in the construction management process, strengthen the technical staff and workers of the norms and standards of training to learn the rules and doing a good job of pre-construction preparations for the construction process to strengthen quality control and supervision and inspection, to play an active construction, supervision and other areas The role of the sub-project to do a good job of the inspection process in order to ensure that the overall quality of the steel works
CAA Golden Bridge Network