control measures for steel structure problems
Because of its own advantages, steel structure has been widely used in modern buildings such as Bridges, industrial plants and high-rise buildings. In the process of a large number of engineering construction, steel structure engineering has also exposed a lot of common quality problems.
Stud welding after the breakdown of galvanized bottom plate (pressed steel plate), stud welding quality can not be guaranteed, in the concrete pouring slurry leakage; Forming is not straight, affecting the appearance of forming.
(1) There is a gap between the floor bearing plate (molded steel plate) and the steel beam before stud welding.
(2) After the floor bearing plate is laid, the steel beam is covered, and the position of the steel beam cannot be accurately judged, and the worker blindly welds the peg by experience; When there is a deviation between the welding position and the steel beam position, the welding fails and directly breaks down the galvanized bottom plate.
(3) The worker is lazy when stitching welding and does not pull the wire in advance.
(1) Strengthen management during the laying of floor plates to ensure that the stud is spot-welded and fixed with the steel beam before welding
(2) The end of the plate and the overlap of the plate edge and the beam shall not have gaps. If the steel truss formwork is warped and the gap between it and the base material is too large, the hand-held lever clamp can be used to locally press the steel truss formwork near the welding place to make it fit with the base material
(3) Before the floor bearing plate is laid, mark the center of the secondary beam at the position mark of the main beam, and then pull through the line to determine the location of the peg.
Neck shrinkage after bolt welding, cracks in the heat affected zone of welding and cracks in the welding flesh and other welding quality defects make it impossible to meet the 30° bending test.
(1) Welding parameters such as the size of welding current and the length of welding time do not meet the requirements
(2) The gap between the floor plate and the steel beam is large, the porcelain ring exhaust is poor, and the impurities on the weldment decompose into gas at high temperature
(3) The upper surface of the steel beam is coated with paint or water stains, and a large number of bubbles exist at the root after welding
(1) Select the appropriate welding process parameters according to the process evaluation
(2) The ground wire is symmetrically connected to the work piece, or an iron plate on the opposite side of the arc deviation to change the distribution of the magnetic field line
(3) Level the surface of the board, reduce the gap, and clean up before welding
(4) The upper surface of the steel beam should not be sprayed with paint as far as possible, and the welding contact surface should be cleaned up with water stains, oil stains and other impurities
(5) Before the formal welding of each specification stud, it is necessary to test weld a stud, knock with a hammer (or use casing pressure) to bend the stud 30°, and check whether the weld meets the quality requirements.
When the floor plate is installed, the length direction of the formwork and the lap length of the steel beam (refers to the distance between the edge of the upper flange of the steel beam and the vertical support steel bar at the end) are less than 5d (d is the diameter of the steel bar at the bottom string of the steel truss) and the larger value of 50㎜; The bonding length between the bottom film and the steel beam in the width direction of the formwork is less than 30㎜, resulting in slurry leakage when concrete is poured.
(1) The deepening design of the floor bearing plate is not rigorous, the length is wrong, and the approach is not accepted
(2) If the floor bearing plate is installed incorrectly, choose a shorter floor bearing plate installation or laying position and the length of the steel beam
(1) Strictly review the floor plate deepening design drawings to ensure that the length of the floor plate deepening is zero errors
(2) Strengthen the acceptance of the floor bearing plate to ensure that the approach floor bearing plate meets the requirements
(3) Organize technical disclosure before the construction of the floor bearing plate, take responsibility to the person, and strengthen management
(4) Before the construction of the floor bearing plate, the control line of the steel truss floor bearing plate is popped out according to the center line of the steel beam.
After the installation of the edge closure plate is obviously bent, not straight, and the position of the edge closure plate is poor after the completion of concrete pouring
(1) The side die and the steel beam are connected by spot welding and the distance is large, and the effective fixation is not formed
(2) The design of the edge plate is L-shaped, and the stiffness itself is not enough
(3) When the factory folds, the Angle is wrong
(1) The weld length between the edge plate and the steel beam should be maintained at 20-30㎜, and the weld spacing is determined according to the spacing of the trough of the pressed metal plate, which is generally controlled at about 300㎜
(2) The edge sealing plate is designed as far as possible to form a “C-section of wide and narrow sides” to increase its own stiffness
(3) If the hand plate is too high, if necessary, spot weld the hand plate with the upper string steel bar of the steel truss floor plate or add the tie steel bar.
Before stud welding, the end of the floor bearing plate is not spot-welded firmly with the steel beam, and the end reinforcement is not added after the on-site steel bar is cut, resulting in the instability of the floor bearing plate and the leakage of concrete.
(1) Disclosure is not in place, and workers do not weld the floor bearing plate and steel beam firmly when installing
(2) The quality awareness of construction management personnel is not strong, ignoring the end of the steel welding process
(1) Construction site management personnel regular inspection, disclosure in place, strengthen management.
(2) Before concrete pouring, carry out concealed acceptance, check the shortcomings and make up for leaks, and add strong end steel bars at the site cut off to ensure that the coal point of the floor bearing plate and steel beam is firm.
The male and female ribs of the adjacent two floor plates are not fastened during the installation of the steel bar truss floor plates, which leads to the leakage of grouting during the concrete pouring.
(1) Steel frame floor bearing plate in the transportation and installation process using wire rope lashing and hoisting, resulting in serious local deformation of the male and female ribs, the gap after fastening is too large.
(2) The installation worker does not buckle the floor bearing plate in place in order to speed up the progress or choose the wrong direction of the board.
(3) The technical level of the installation worker is poor, and the sealing plate of the molded steel plate is not welded in place.
(1) Optimize the fixing method of the floor bearing plate during transportation, and use Angle steel for packaging. It is strictly prohibited to fix the packed floor bearing plate directly with steel wire rope.
(2) Two or more points are used when the floor bearing plate is hoisted.
(3) Ensure tight occlusion between the steel bar standard frame floor bearing plate.
There are welding slag, welding scars, dust, concrete, oil stains on the surface of steel components, and the quality of rust removal can not meet the standard requirements. After a long time, the rust phenomenon appears again.
(1) When the factory is processed, the rust is not thoroughly removed or the rust is directly sprayed on the paint
(2) The construction site docking out of the rust is not thorough, does not meet the design of the rust level requirements
(3) The finished product is not protected in place during transportation, and the paint is damaged
(4) The film thickness is not enough
(1) The rust removal level before formal painting must meet the design requirements.
(2) Before painting, the welding slag, welding scar, dust, oil, and burr and other attachments on the steel surface should be cleaned, and the rust removal grade should meet the design requirements.
(3) Protection of finished products during component transfer.
(4) Do the paint film thickness detection during the process.
In the vertical coating surface or the groove of the line Angle, the paint produces flow. The formation of uneven film thickness, serious such as hanging curtain sag, light such as beaded tears
(1) the diluent is excessive, so that the adhesion is lower than the normal construction requirements, and the surface of the object cannot be attached to fall
(2) The construction environment temperature is too low, and the drying speed of the paint is too slow
(3) The paint brush selected by the worker is too large, the hair is not long, is too soft, or the oil is too much when brushing, so that the thickness of the paint is different
(4) The spraying distance is too close and the spraying Angle is improper
(1) The selection of excellent paint materials and appropriate thinner
(2) Paint construction environment temperature control at 5-38 degrees, humidity control should not be greater than 85%
(3) The paint brush selected by the worker should not be too large, the hair should not be too long and too soft, it should be elastic, with thick and thin tips. The brush should be dipped in oil less often.
(4) When brushing, force evenly, do not paint horizontally. Use a brush to gently connect the edges and corners, and dip the excess paint into a smooth opening to avoid too thick and flowing paint film
(5) Thoroughly clean the coated surface of debris, oil, water and other debris
(6) When the paint film is not completely dry, and the paint falls on one side or part of a surface, the excess paint can be removed with the spatula knife and then painted again. If the paint film has been completely dry, for light loose fall, can be sanded, for large area fall, can be sanded with water.
The cracks of different depth and size on the surface of the coating film are called “cracking”; If the film shows small cracks like turtle back flower pattern, it is called “crack”
(1) Fireproof paint is not compatible with primer.
(2) Each coating is too thick, and the lower layer of fireproof coating is not dry.
(3) The ratio of fireproof paint is not suitable.
(1) The steel structure base must be cleaned up and inspected by special personnel.
(2) The paint should be compatible with the fireproof coating, and the fire-proof coating sample should be made before the construction of the large-scale fire-proof coating.
(3) After the first coating is dry, each coating should not be too thick, and the thickness of each coating should not exceed 2.5mm; The thickness of each coating should be 5-10mm.
(4) Construction under appropriate environmental conditions, fully stir the fireproof paint before painting.
After the construction of fireproof paint, it is damaged and fallen off by the subsequent construction team
(1) Failure to disclose to the subsequent construction team
(2) On-site staff have insufficient awareness of finished product protection
(1) Disclose to the subsequent construction team after the completion of construction
(2) After the completion of construction, make appropriate warning and collision prevention measures
(3) Most of the subsequent work is manually repaired after completion
Because the length of the roof of the metal roof is far beyond the limit of the processing equipment, it is inevitable that a number of roof cover plates must be lapping in turn, and the lapping length must be guaranteed to be greater than 250㎜. However, in the field construction, there will be insufficient lap size. Causing the roof ridge part of the water leakage.
(1) Reducing the length of the lap can reduce the use of roof cover plates, sealant and butyl tape, reduce working time, and there is a jerry-cutting behavior of operators
(2) The project department has not made a special disclosure to the labor personnel, and the operators do not know that they must build more than 250㎜.
(1) Conduct pre-job training and technical disclosure, and clarify node requirements
(2) Strengthen construction management, and carry out a large proportion of random inspections of nodes in construction
(3) Pre-layout, and check the number of construction nodes according to the layout of the drawings.
The size of metal roof into the gutter is not always, resulting in uneven roof cornice not only affect the appearance but also lead to rain leakage.
(1) In the early stage of construction, the line was not levelled at the cornice position.
(2) During the construction process, the worker’s awareness is insufficient, and the installation of the plate is not corrected.
(1) Before the construction of the roof slab, a normal straight line of at least 10m must be pulled at the cornice position.
(2) Carry out pre-job training and technical disclosure work, and clarify the length of cornice protruding.
(3) Strict requirements in the construction process, and the construction party is required to rectify the unqualified locations.
The metal sliding roof uses sliding brackets to bite the two adjacent plates at the joint, and uses self-tapping nails at the beginning and end of the two positions to directly fix the structure without sliding ability. This will cause the plate at the gable to expand and contract due to heat and tear.
(1) The structure of the gable sliding component is complex, and the technical ability of the corresponding company is high, and many small and medium-sized enterprises have no corresponding treatment method.
(2) The cost of gable sliding components is high, enterprises are not willing to provide, the construction team is not willing to install.
(3) The construction personnel did not realize the importance of waterproofing the entire roof here, and did not opportunist according to the drawing.
(1) The roofing system sheet suppliers are screened, and the merchants whose technical capabilities meet the requirements are selected.
(2) Conduct pre-job training and technical disclosure, and emphasize the importance of this.
(3) Strict requirements in the construction process, the project department construction management personnel tracking the whole process, the hidden steps in the construction process, need to submit acceptance before the next process.
The sliding bracket used by the metal sliding roof plate is not placed in a reasonable position according to the construction season. This behavior will lead to the roof resistance to thermal expansion and contraction of the decline, or even loss.
(1) The construction personnel do not understand the principle, no matter where the position of the slide is when installing the bracket, it is directly used.
(2) Adjusting the position of the slide will reduce the installation speed, and the construction personnel are reluctant to adjust.
(3) The project construction management personnel have loose requirements for the construction team and indulge their behavior.
(1) Conduct pre-job training and technical disclosure, and emphasize the importance of this.
(2) The sliding pick of the sliding bracket determines its position according to the temperature during the construction period relative to the temperature of the whole year, under normal circumstances, the position of the summer is placed uphill, the position of the winter is placed downhill, and the spring and autumn are placed in the middle.
(3) Strict requirements in the construction process, and the construction party is required to rectify the unqualified locations.
The internal slope leads to water accumulation or the rainwater is guided to the external wall due to the external slope, resulting in the wall being polluted.
(1) The depth design unit did not consider the provision of slope drainage at the detail design stage.
(2) The construction personnel did not carry out the construction according to the drawings, did not seek the construction speed and did not do the internal safety construction part structure.
(1) Review the drawings provided by the deepening design unit and require that internal slope construction measures must be done.
(2) Carry out the pre-job technical disclosure work, and inform the construction personnel of the internal slope practice in detail.
(3) Strict requirements in the construction process, the construction management personnel of the project department track the construction of the inner slope structure throughout the process.
The metal pressed plate roof is overlapped at the position of the light plate. Because the construction sequence is from uphill to downhill construction, the lower plate is pressed on the surface of the upper plate at the overlapped position.
(1) The construction personnel have no experience and decide the lap order according to the construction order.
(2) In order to speed up the construction speed and reduce the construction interval.
(1) During the technical disclosure, explain the lap sequence to the construction personnel: the uphill plate of the lap position is on the top, and the downhill plate is on the bottom.
(2) During the construction process, focus on checking the position of the lap joint and correct the problem immediately.
The vertical folding piece of the wall hole is pressed on the outside of the upper horizontal folding piece. Or the vertical folding piece is pressed inside the lower horizontal folding piece.
(1) The operator is inexperienced and does not know the basic principle of drainage.
(2) The project management personnel did not disclose the construction technology or the disclosure was not targeted.
(3) The operator construction at will.
(1) Explain the lap sequence to the construction personnel when the technical disclosure: the upper edge piece should be on the outside, the lower edge piece should be on the inside.
(2) Therefore, for careful work, the construction personnel should be clearly required to have the construction experience of window Haitang corner.
(3) Check the position of the lap joint during the construction process, and correct the problem immediately.
Brick wall flooding edge pieces travel wavy pattern, ups and downs, internal and external convex. Seriously affect the aesthetic appearance of the building facade.
Cause analysis
(1) Affected by the civil sill wall, the sill wall is not flush, resulting in the bending pieces attached to it are not flush.
(2) Horizontal pay-off was not done in the initial stage of construction.
(3) Lack of quality awareness during construction, random placement, not in accordance with the horizontal line construction.
(4) The deepened drawing did not take into account the possible situation of the brick wall on site, and the size of the bending parts was insufficient.
(1) In the deepening stage, carefully review the gap between the site brick wall and the drawing to avoid inconsistencies.
(2) Before construction, it is necessary to review the top elevation of the sill wall and its error range. If the error exceeds 10mm, the deepening design unit should be notified in advance.
(3) The horizontal line must be set during the construction process, and the installation should be based on the level of the horizontal line, and cannot be placed at will.
There is a gap in the hot air welding, and the TPO material is not tightly bonded
(1) The operator of hot air welding is inexperienced and the skill level is not up to standard
(2) Before hot air welding, the contact surface debris is not cleaned
(1) Select a high-quality team, requiring hot air welding operators must have a lot of engineering experience
The project management personnel focus on the control of this construction, and the unqualified situation requires immediate rectification.
The roof is penetrated and damaged by sharp objects during the construction process, resulting in leakage points.
(1) There are many and miscellaneous tools on the construction site, and the protection consciousness of finished products is weak
(2) No special disclosure to the follow-up operation team, pay attention to the protection of finished products
(1) Strengthen site management and repeatedly educate construction personnel on the protection of finished products
(2) Control sharp objects to minimize the number of sharp objects on the roof
(3) Strengthen the examination, and make up for the puncture situation in time.
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