Common problems and solutions in steel structure’s construction

The steel structure is widely used in modern buildings such as industrial plants, workshops, storage warehouses, and high-rise buildings due to its own advantages. In the process of a large number of projects, steel structure projects have also exposed many common quality problems. This article mainly shares common problems and rectification measures in steel structure construction.

Component Production

The plate used in the portal steel frame is very thin, and the thinnest plate is 4 mm thick. Instead of flame cutting, the physical cutting should be taken as the first choice when cutting the thin plates. Because flame cutting will produce great wave deformation on the edge of the plate. At present, most manufacturers adopt automatic submerged arc welding or semi-automatic welding. If the control is not good enough, then the welding deformation will occur, which will cause the component to bend or twist.

Column Bottom Installation

1.Problem: Embedded parts (anchor bolts) problems, the overall or layout is offset, the elevation is wrong, the threaded fasteners are not protected. All of these problems will cause the bolt holes of the steel column bottom plate to be misaligned and the thread’s length is not long enough.

Solution: The steel structure construction unit should cooperate with civil construction unit to complete the embedded parts work. The relevant dimensions must be checked to fix the embedded parts firmly before the concrete is poured.

2.Problem: Anchor bolts are not vertical. The level of the frames column base plate is poor, the anchor bolts are not vertical, and the horizontal error of the embedded anchor bolts after foundation construction is too large. After installation, the pillars are not in a straight line, and they sway from side to side, which makes the appearance of the steel structure ugly, and brings errors to the installation of steel pillars, and the structure is affected by force, which does not meet the requirements of construction acceptance specifications.

Solution: The anchor bolt installation should insist on leveling the bottom plate with the lower adjusting bolt firstly, and then fill it with secondary grouting. When the anchor bolt is installed, fixed anchor bolts such as steel bars or angle steel can be used. Weld into a cage to improve the support, or take some other effective measures to avoid displacement of the anchor bolts when the foundation concrete is poured.

3.Problem: The anchor bolts of the column foot are not tightened, and the backing plate is not welded to the bottom plate. Part of the anchor bolts with 2 to 3 threads that arenot exposed.

Solution: Weld anchor rods and nuts. On the outside of chemical anchor bolts, fire-resistant coatings and heat insulation treatment should be strengthened to prevent the anchoring performance from being affected in the event of fire. Foundation settlement observation data should be supplemented.

Connection

1.The bolt equipment surface does not meet the requirements, which causesthe bolts to be difficult to install, or the degree of bolt fastening does not meet the design requirements.

Analysis of causes:

2.There are impurities such as floating rust and oil stains on the surface, and the bolt holes have burrs and weld bumps.

3.Although the bolt mounting surface has been processed, there are still defects.

Solution:

1.The surface rust, oil stain and bolt hole wall problems of the high-strength bolt should be cleaned up one by one. It must be treated with rust prevention before use. The bolts should be kept and distributed by special personnel.

2.The assembly surface should be treated with consideration of the construction and installation sequence to prevent repetition, and try to deal with it before hoisting.

3.The threadof the bolt is damaged, and the screw cannot be screwed into the nut freely, which affects the bolt assembly.

Analysis of causes:

The thread is severely corroded.

Solution:

1.Bolts should be selected before use, and used as spare parts after cleaning and derusting.

2.Bolts with damaged threads cannot be used as temporary bolts, and it is strictly forbidden to force them into the screw holes.

3.The pre-selected bolt components should be stored in sets and cannot be interchanged during use.

Steel Structure Installation

Before the steel column is hoisted, the foundation elevation should be strictly controlled, the measurement should be accurate, and the foundation surface should be carefully leveled according to the measured value. If the secondary grouting method is used, then grouting holes are made in the bottom of the column base, the unevenness of the bottom of the steel column is leveled by the steel backing plate, and the steel plate of the column base is placed in advance according to the design elevation, and then the secondary grouting is adopted.

The steel column should be hoisted in place according to the calculated hanging point, and a more than two points hoisting method must be used. Temporary fixing should be carried out during hoisting to prevent lifting deformation. Temporary support should be added in time after the steel column is in place. The vertical deviation of the beam should be corrected before fixing.

During the process of construction management, the workers should strengthen the training and learning of standards and operating procedures, and the preparations should be made before starting construction, and the quality control should be strengthened to ensure the overall quality of the steel structure project.

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