Some problems in the construction of steel structure and their solutions

Solar Panel Flat Roof Mounting System - Galvanized 125*65 Fuse Cutout Solar Mounting Channel – Rainbow

Because of its advantages, steel structure has been widely used in modern buildings such as Bridges, industrial workshops and high-rise buildings.In the process of a large number of engineering construction, steel structure engineering also exposed a lot of quality problems.This paper mainly discusses the common problems and rectification measures in the acceptance and completion of steel structures in Liaoning province in recent years.

Part of the problems in the construction of steel structures and their solutions

1. Production of components
The panels used for portal steel frames are very thin and can be as thin as 4 mm.The cutting method should be preferred to avoid flame cutting.Because the flame cutting will cause the edge of the plate to create a large wave deformation.At present, most of h-beam welding manufacturers are using submerged arc welding or semi-automatic welding.If the control is not good, welding deformation should occur, so that the members bend or twist.

2. Installation of pillar foot
(1) Embedded parts (anchors) : overall or layout deviation;Wrong elevation;The thread is not protected.The bolt hole of steel column bottom plate is out of position and the thread length is not enough.
Measures: The steel structure construction unit shall cooperate with the civil construction unit to complete the embedment work before concrete pouring and ramming.The relevant dimensions must be checked and fixed firmly.

(2)anchor bolts are not vertical, and the horizontal error of embedded anchor bolts is large after foundation construction.After the column is installed, it is not on a straight line, and it is tilted from side to side, which makes the appearance of the house very ugly. It brings errors to the steel column installation, and the structure stress is affected, which does not meet the requirements of the construction acceptance code.
Measures: anchor bolt installation should adhere to the bottom plate with the lower adjusting bolt leveling, then fill with non-shrinkage mortar secondary grouting, foreign construction method.So when the anchor bolt construction, can use the steel bar or Angle steel and other fixed anchor bolt.Weld into a cage, perfect the support, or take some other effective measures to prevent the anchor bolt from moving when pouring the foundation concrete.

(3) Problem of anchor bolt connection: the anchor bolt at the pillar foot is not tightened, and the backing plate is not welded with the bottom plate;Partially unexposed 2 ~ 3 thread bolts.
Measures: welding bolts and nuts should be adopted;On the outside of the chemical anchor bolt, fireproof paint and heat insulation should be added to prevent the anchorage performance from being affected by fire.Observation data of foundation settlement should be supplemented.

3. Connection problem
(1) High-strength bolt connection
The bolt equipment surface does not meet the requirements, resulting in difficult installation of bolts, or the degree of bolt fastening does not meet the design requirements.
Reason analysis:
A. There are floating rust, oil and other impurities on the surface, bolt holes burr, welding tumor, etc.
B. although the bolt mounting surface has been processed, there are still defects.
Solutions:
a: The surface of high-strength bolts should be cleaned up one by one for floating rust, oil and bolt holes.The bolts that must be treated with rust prevention before use shall not be used in formal assembly.Bolts shall be kept and issued by special persons.
b: the handling of the assembly surface should take into account the construction and installation sequence, to prevent repetition, and try to be handled before hoisting.

If the screw thread of the bolt is damaged, the screw cannot be freely cocked into the nut, which will affect the assembly of the bolt.
Cause analysis: The wire buckle was seriously corroded.
Solutions:
(1) Bolts should be selected before use, after cleaning rust for pre-matching.
(2) screw damaged bolts can not be used as temporary bolts, do not force into the screw hole.
(3) The pre-selected bolt assembly shall be stored according to the sleeve, and shall not be exchanged when used.
(1) The surface of high-strength bolts should be cleaned up one by one for floating rust, oil and bolt holes.The bolts that must be treated with rust prevention before use shall not be used in formal assembly.Bolts shall be kept and issued by special persons.
(2) the handling of the assembly surface should take into account the construction and installation sequence, to prevent repetition, and try to be handled before hoisting.
(2) On-site weld phenomenon: quality is difficult to be guaranteed;The design requires that the first and second grade welds with full penetration should not adopt ultrasonic flaw detection;The main beams and columns of the floor are not welded;No arc plate is used for welding.
Solution: steel structure before welding, the welding of the inspection certificate, welding article contains the selection according to design requirements, according to the instructions and procedures require the use of electrode, the weld surface must not have crack, flash, a, level 2 weld can not have porosity, slag, crater crack, level of weld shall bite edge, under welding defects, such as a, level 2 weld nondestructive testing, in accordance with requirements in the weld and parts of the rules to check the welder’s seal.The unqualified welds shall not be disposed without authorization, and shall be disposed after the modification process is determined. The frequency of weld repair in the same part shall not exceed two times.

4. Deformation of components
(1) The component is deformed during transportation, resulting in dead or slow bending, which makes the component unable to be installed.
Reason analysis:
1) Deformation caused by welding during the fabrication of components generally presents slow bending.
2) When the components are to be transported, the supporting cushion points are unreasonable, such as the upper and lower cushioning wood is not perpendicular, or the stacking site is sunken, resulting in dead bending or slow deformation of the components.
3) In the transportation of components, deformation is caused by collision, which generally presents dead bend.
Preventive measures:
1) Measures to reduce welding deformation shall be adopted in the fabrication of components.
2) In assembly and welding, measures such as reverse deformation shall be adopted. The assembly sequence shall follow the welding sequence. The assembly molding tool shall be used and enough supports shall be set to prevent deformation.
3) To be shipped and transported, pay attention to the reasonable configuration of cushion points.
Solutions:
1) Dead bending deformation of members is generally treated by mechanical correction method.Use jack or other tools to correct or with oxyacetylene flame after correction.
2) Take oxyacetylene flame heating to correct the slow bending deformation of the structure.
(2) After assembling the steel beam members, the full length distortion exceeds the allowable value, resulting in poor installation quality of the steel beam.
Reason analysis:
1) Unreasonable stitching process.
2) The size of assembly nodes does not meet the design requirements.
Solutions:
1) Assembly members shall be equipped with assembly table, which shall level the bottom surface of the members during welding to prevent warping.The assembly table should be horizontal fulcrum, welding deformation should be prevented.Especially for the final assembly of the beam section or stairway, it is necessary to adjust the deformation after positioning welding, and pay attention to the size of the joints in accordance with the design, otherwise the members will easily be distorted.
2) Members with poor rigidity should be strengthened before turning over and leveled after turning over, otherwise they cannot be corrected after welding.
(3) When members arch, the value is dry or less than the design value.When the arch value of the component is small, the rear beam of the installation is bent downward.When the arch value is large, the extrusion surface elevation is easy to exceed the standard.
Reason analysis:
1) The size of components does not meet the design requirements.
2) During erection, no correction is made according to the discrepancy between measured and calculated values.
3) Bridges with small span have small arch degree and are ignored in assembly.
Solutions:
1) Inspect each step strictly according to the allowable deviation of steel structural members.
2) During erection, the upper arch degree shall be measured after the rod parts are installed and the joint on site is completed, and other adjustments shall be made during construction.
3) In the small assembly process, the accumulated deviation should be strictly controlled and measures should be taken to eliminate the influence of welding shrinkage.

5. Installation of steel structure
(1) Before the steel column is lifted, the elevation of the foundation shall be strictly controlled and measured accurately, and the foundation surface shall be leveled carefully according to the measured value;If the secondary grouting method is adopted, the pouring hole (double as the exhaust hole) is opened in the bottom of the column, the uneven place at the bottom of the column is flattened with the steel backing plate, and the steel plate at the base of the column is arranged according to the design elevation in advance, and then the secondary grouting is adopted.
(2) Before the concrete foundation is poured, the embedded bolts shall be stuck according to the design position by using the stereotyped chuck to prevent the displacement from occurring during the pouring of concrete;The reserved hole of column low steel plate should be enlarged, and the reserved hole should be made after determining the location of the hole.
(3) The steel column should be lifted in place according to the calculated hanging point, and the lifting method above two points must be adopted. During the lifting, it should be temporarily fixed to prevent the lifting deformation;Temporary support should be added in time after the column is in place;The vertical deviation should be corrected before fixing.
Second, the conclusion
Only in the process of construction management, strengthen the technical personnel to the specification standards and operational procedures, workers training study, the real ready to before construction, strengthen the quality control in the process of construction, supervision and inspection, active play to the role of the construction, supervision and so on various aspects, do a good job in the process of the sectional works acceptance to guarantee the overall quality of the steel structure engineering.

Our Main Product Range:

1. Steel Pipe (Round / Square/ Special shaped/SSAW)

2. Electrical Conduit Pipe (EMT/IMC/RMC/BS4568-1970/BS31-1940)

3. Cold Formed Steel Section (C /Z /U/ M )

4. Steel Angle and Beam ( V Angle Bar / H Beam / U Beam)

5. Steel Scaffolding Prop

6. Steel Structure (Frame Works)

7. Precision Process On Steel ( cutting, straightening, flattening, pressing, hot rolling, cold rolling, stamping, drilling, welding, etc. According to customer’s requirement )

8. Steel Tower

9. Solar Mounting Structure


Tianjin Rainbow Steel Group Co., Ltd.

Tel:  0086-22-59591037

Fax: 0086-22-59591027

Mobile: 0086-13163118004

E-mail: tina@rainbowsteel.cn

Wechat: 547126390


Some problems in the construction of steel structure and their solutions Related Video:


While using the "Client-Oriented" organization philosophy, a rigorous top quality command process, highly developed production devices and a potent R&D workforce, we normally provide high quality products, outstanding solutions and aggressive charges for Rigid Conduit Pipe , Flexible Pipe For Electrical , Hot Rolled Steel Coil , To achieve reciprocal advantages, our company is widely boosting our tactics of globalization in terms of communication with overseas customers, fast delivery, the best quality and long-term cooperation. Our company upholds the spirit of "innovation, harmony, team work and sharing, trails, pragmatic progress". Give us a chance and we will prove our capability. With your kind help, we believe that we can create a bright future with you together.