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Problems and solutions during Steel Construction

Because of the advantage of Steel Structure ,widely used in bridges, industrial plants, high-rise buildings and other modern buildings. In a lot of the construction process, the steel Structure also exposed many quality defects .
First, the construction of part of the steel structure engineering problems and solutions
1,Component fabrication problem
Portal frame used thin plate , the thinnest available to 4 mm . Multi- sheet cutting shear mode should be preferred to avoid flame cutting. Because flame cutting board edge will have a huge wave deformation. Most of the current H-beam welding manufacturers are using submerged arc welding or GMAW . Should not occur if the control of welding deformation, so that means bending or twisting.
2 Anchor Bolt installation problems
( 1 ) embedded parts ( anchor ) Description: The offset , in whole or layout ; elevation is incorrect ; threaded protective measures are not taken . A direct result of the steel column base plate bolt hole right position , causing the threaded length is not enough .
Measures: Steel construction unit coordinated civil construction units to work together to complete the embedded parts , before ramming the concrete pouring . Must review the relevant dimensions and fixed firmly.
( 2 ) anchor is not perpendicular to the phenomenon : Frame Column foot plate levelness framework is poor, not vertical anchors , anchor bolts embedded foundation construction after the level of error is too large . After installing the column is not a straight line , stagger, so that the appearance of ugly houses , installation of steel columns to bring the error , force structure is affected, do not meet the acceptance requirements of the construction .
Measures: anchor bolt installation should adhere to the first floor with the lower part of the leveling adjustment bolt , then no shrink grout mortar secondary infill abroad this construction method . So when the anchor construction , such as steel or angle can be a fixed anchor . Welded into a cage-like , perfect support , or take some other effective measures to prevent the anchor shift a concrete foundation when watering .
( 3 ) Anchor connectivity issues phenomenon : not tighten column anchor , not the bottom plate welding ; part 2 ~ 3 threaded anchor not disclosed.
Measures: welding bolt and nut should be taken ; in chemical anchor outside , should be thick and insulated fire retardant coatings , affect performance when anchoring in case of fire ; should be tested additionally foundation settlement observations.
3 , connection problems
( 1 ) high-strength bolts
Degree 1 ) bolt face is not equipped to meet the requirements , causing the bolt not installed or bolt does not meet the design requirements.
① surface rust , oil and other impurities , bolt hole bi burrs , welding aneurysm.
② bolt mounting surface treated , although there are still flaws.
High-strength bolts ① surface rust , oil and bolt holes bi illnesses , should be cleaned individually . Must be approved by anti-rust treatment , so assembled with bolts before use , shall not be used in the official assembly . Bolt custody and released by hand .
② handle mounting surface should take into account the order of construction and installation , to prevent the repeated lifting and try to deal with before .
2 ) damage to the bolt threaded screw screwed into the nuts are not free , the impact of mounting bolts .
Analysis: threaded severe corrosion .
① bolts should be chosen before use , cleaning rust made ​​after provisioning .
② bolt threaded bolt damage can not be done using a temporary , non- forcible scored holes .
③ optional bolt assembly shall be pre- set storage, shall not be interchangeable use.
( 2 ) field weld phenomenon: the quality is difficult to guarantee ; design requirements for full penetration of one , two welds did not use ultrasonic testing ; main floor beams and columns are not welding ; did not use arc welding plate .
Solution: steel welding before the certificate for welding checks , according to the design requirements with the choice of welding , according to the instructions and procedures require the use of welding , weld surface without cracks , welding tumor , one, two welds there shall be no pores, slag , crater cracks , welds may not have undercut level , under welding defects , one or two non-destructive testing as required weld , the weld and parts required to check the welder’s stamp . Substandard welds are not allowed to deal with , and then modify the process set processing , weld repair times should not exceed twice the same site .
4 , deformation components
( 1 ) member deformation occurs during transport , appear dead or slow bend bend, causing components can not be installed .
1 ) When welding deformation generated by the production of components , generally showing slow bends.
2) The member is to be transported , support pad point unreasonable , such as up and down vertically, or stacked skids venues not happen subsidence, so members have dead or slow bending deformation .
3 ) transport component deformation due to collision , generally showing dead corner .
Preventive measures:
1 ) when the component production , the use of measures to reduce the welding deformation .
2 ) assembly welding , deformation and other measures adopted in the opposite direction , welding assembly sequence should obey the order , the use of tires with the assembly , set up a sufficient number of stents to prevent deformation.
3 ) to be transported and transportation , note pad rational allocation of points .
1 ) member died bending deformation , the general mechanical correction method of governance . That jack or other tools to correct or supplemented after oxyacetylene flame grilled correction.
2 ) Slow bending deformation structure , take oxyacetylene flame heating correction.
(2 ) total length of twisted steel beams assembled exceeds the allowable value , resulting in poor quality of the installation of steel beams .
1 ) splicing process is unreasonable.
2 ) assembling node size does not meet the design requirements.
1 ) To set up assembly member assembly workbench , when you want to solder components as leveling the underside to prevent warping . Assembling the table should be the pivot level, to prevent welding in welding deformation . Especially the final assembly beams or stairway , to adjust the tack welding deformation , pay attention to meet the design node size , otherwise easily lead to distortion components .
2 ) own less rigid member , before turning to welding reinforcement should also stand up for leveling rear member , member or can not be corrected after welding .
( 3 ) members bagging, or less than the design value of big value . Member bagging numerical hour , installed rear spar torsion ; bagging value is large, easy to produce extruded surface elevation exceeded.
1 ) component size does not meet the design requirements .
2 ) erection process is not carried out in accordance with amendments to the measured and calculated values.
3 ) small span bridges , bagging a smaller degree , when assembled ignored.
1 ) strictly in accordance with the production of steel components allow deviation of each step test.
2 ) In the course of erection , rods and equipment is completed, and after the joint construction sites , have carried on the camber measurements and make adjustments to the other in construction.
3 ) In a small assembly process , the cumulative deviation should be strictly controlled , note taking measures to eliminate the influence of the welding shrinkage .
5 Steel installation problems
( 1 ) foot steel column there is a gap before lifting steel columns pre-control measures should be strictly controlled base elevation , accurate measurement, according to their measurements on the basis of the surface carefully leveling ; such as the use of secondary grouting method , the column foot plate open watering hole ( doubles vent ) , the use of steel plate at the bottom of the steel columns uneven pad level , and pre- press design elevation settle pedestal bearing plate, then take the second grouting.
After the column should be enlarged lower plate holes for samples to determine the hole ; ( 2 ) Pre- steel column displacement control measures before pouring the concrete foundation , the application will be embedded stereotypes chuck stuck bolt position by design to prevent displacement occurs when concreting further aside holes.
( 3 ) pre- column vertical deviation is too large steel column should be calculated control measures hoisting rigging points , two points above and must adopt the method of lifting , hoisting should be temporarily fixed to prevent lifting deformation ; column in place after timely additional temporary support ; vertical deviation and should be corrected prior to fixation .
Only in construction management process, strengthen the technical personnel, workers of standards and procedures for training to learn to effectively prepare pre-construction , construction process to strengthen quality control and supervision , actively play all aspects of construction, supervision , etc. role , do the work of the sub- process inspection project, in order to ensure the overall quality of steel works.