Due to its own advantages, steel structures are widely used in modern buildings such as bridges, industrial plants and high-rise buildings. In a large number of project construction process, steel structure project also exposed a lot of quality common problems. In this paper, we mainly talk about the common problems in acceptance and final acceptance of steel structures in Liaoning Province and the corrective measures in recent years.
First, part of the steel structure construction process and solutions
1.component production problems
The gantries used for the gantry are very thin, and the thinnest is 4 mm. Multi-sheet cutting should be the preferred shear mode to avoid flame cutting. Because the use of flame cutting plate edge will have a great wave deformation. The current H-beam welding most manufacturers are using submerged arc welding or semi-automatic welding. If the control is not good welding deformation occurs, so that the components are bent or twisted.
2. column foot installation problem
(1) embedded parts (anchor) Problem phenomenon: the overall or layout offset; elevation error; threading did not take protective measures. Directly caused by the steel plate floor bolt hole is not aligned, resulting in lack of threaded length.
Measures: The steel structure construction unit, together with the civil construction unit, will complete the work of embedding the pieces before pouring the concrete. Must review the relevant size and fixed firmly.
(2) The phenomenon that the anchor bolt is not vertical: the horizontal difference of the foot column of the frame column and the anchor bolt is not vertical, and the horizontal error of the embedded anchor bolt after foundation construction is large. Column is not installed in a straight line, staggering east, so that the appearance of housing is not easy to see, to the installation of steel columns bring error, the structure affected by force, does not meet construction acceptance requirements.
Measures: Anchor bolt installation should be the first to adjust the bottom of the bottom leveling bolt leveling, and then fill the secondary grouting mortar non-shrinkage, foreign law construction. Therefore, anchor bolt construction, can be used steel or angle anchor bolts and other fixed. Welded into a cage, improve the support, or take some other effective measures to avoid pouring anchor concrete anchor when the shift.
(3) the phenomenon of anchor bolt connection: column foot bolt is not tightened, the plate is not welded with the floor; some did not reveal 2 to 3 threaded buckle anchor.
Measures: Welding anchor rod and nut should be taken; outside of chemical anchor bolt, thickening fire-retardant coating and heat-insulating treatment should be thickened to prevent the anchorage performance from being affected by fire; supplementary observation data of foundation subsidence should be made up.
3.the connection problem
(1) high-strength bolt connection
1) Bolt equipment surface does not meet the requirements, causing the bolt is not good to install, or the degree of bolt does not meet the design requirements.
①floating rust on the surface, oil and other impurities, bolt holes Bi burr, welding tumor.
②Although the bolt installation surface is still defective.
①high-strength bolt surface rust, oil and bolt holes, should be cleaned one by one. Before use must be rust-proof treatment, so that the bolts used in assembly shall not be used in the official assembly. Bolts should be kept and distributed by hand.
②processing assembly surface should take into account the construction and installation order to prevent duplication, and try to handle before lifting.
2) Screw thread damage, the screw can not be screwed into the nut, affecting the assembly of the bolt.
Analysis: Serious serious rust wire.
①bolts should be used before the selection, after cleaning rust pre-prepared.
②threaded threaded bolts can not do temporary use of bolts, forbidden into the screw.
③pre-optional bolt assemblies should be stored in sets, shall not be used interchangeably.
(2) The phenomenon of on-site weld: the quality is difficult to guarantee; design requirements full penetration of the first and second welds did not use ultrasonic testing; floor girders and columns are not welded; not using arc plate welding.
Before the welding of steel structure, check the welding certificate, according to the design requirements of the selection of welding strip, according to the instructions and procedures require the use of electrodes, the surface of the weld shall not be cracked, welding tumor, one or two welds There shall be no holes, slag inclusions, crater cracks, a weld may not undercut, under welding and other defects, the first and second welds nondestructive testing as required, the provisions of the welds and parts to check the welder's seal . Unqualified weld shall not be handled without permission, set out to modify the process after treatment, the same part of the weld repair times should not be more than twice.
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