Steel structure works one of the main building structure types. Is one of the more common structural forms of modern construction. China is the first iron-bearing load-bearing structure of the country, steel structure is based on steel production structure. The main structure of the steel structure is one of the main building structures. Steel is characterized by high strength, light weight, good overall rigidity, deformation ability, it is used to build large span and high, super-heavy buildings are particularly suitable; material homogeneity and isotropic, is the ideal elastomer , The most suitable for general engineering mechanics of the basic assumptions; material plasticity, toughness, and may have a greater deformation, can withstand the dynamic load; construction period is short; its high degree of industrialization, can be highly specialized mechanized production. Steel structure in the future should study high-strength steel, greatly improve its yield point strength; in addition to rolling new varieties of steel, such as H-beam (also known as wide flange steel) and T-shaped steel and steel plate to adapt to large span structure And the need for high-rise buildings.
First, the steel structure of the construction process of some of the problems and solutions
1, the production of components of the problem
Door plate used in the plate is very thin, the thinnest can be used to 4 mm. Multi-sheet cutting should be preferred to cut the way to avoid flame cutting. Because the use of flame cutting will make a large wave edge 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, so that the components bent or twisted.
2, column installation problems
(1) embedded parts (anchor) problem phenomenon: the overall or layout offset; elevation is wrong; thread did not take protective measures. A direct result of steel column bottom plate bolt hole is not bit, resulting in thread length is not enough.
Measures: steel construction units in conjunction with civil construction units together to complete the embedded parts work before concrete pouring. Must check the relevant size and fixed firmly.
(2) the bolt is not vertical phenomenon: the column column foot plate level difference, the bolt is not vertical, the foundation after the laying of embedded anchor level error is too large. After the installation of the column is not a straight line, east and west, so that the appearance of the house is ugly, to the installation of steel columns to bring the error, structural stress affected, does not meet the construction acceptance requirements.
Measures: bolt installation should adhere to the first floor with the lower part of the adjustment bolt leveling, and then no shrinkage mortar filling the second filling, foreign construction of this method. So anchor construction, can be used out of steel or angle and other fixed bolt. Welded into a cage, perfect support, or take some other effective measures to avoid watering the base of concrete when the anchor to move a bit.
(3) bolt connection problem phenomenon: the column anchor bolt is not tightened, the pad is not welded with the floor; part of the exposed 2 to 3 clips of the bolt.
Measures: should be taken to weld the bolt and nut; in the chemical anchor outside, should be thicker fire retardant coating and heat treatment to prevent damage to the impact of anchoring performance; should be measured base settlement observation data.
3, the connection problem
(1) high-strength bolts
1) bolt equipment surface does not meet the requirements, resulting in poor bolt installation, or the degree of bolt tightening does not meet the design requirements.
① surface floating rust, oil and other impurities, bolt holes are burr, welding and so on.
② Although the installation of the bolt is still defective.
① high-strength bolts on the surface of floating rust, oil and bolt holes, should be cleaned up one by one. Before use must be rust-proof treatment, so that the assembly of the bolts, not in the official use of assembled. Bolts should be kept and dispensed by hand.
② handling assembly surface should take into account the installation sequence, to prevent duplication, and try to handle before the lifting.
2) bolt thread damage, the screw can not be screwed into the nut, affecting the assembly of bolts.
Analysis of reasons: serious cracks in the thread.
① use the front bolts should be selected, cleaning rust after the pre-allocation.
② thread damage the bolt can not do temporary bolts, is strictly forcibly into the screw hole.
③ pre-matching bolt components should be stored according to the set, the use of not interchangeable.
(2) the scene of the weld phenomenon: the quality is difficult to guarantee; design requirements of the whole penetration of the first and second welds are not used ultrasonic testing; floor main beam and column without welding;
Solution: steel structure before welding, the electrode of the certificate to check, according to the design requirements of welding with the article, according to the instructions and operating procedures require the use of electrodes, weld surface shall not have cracks, welding tumor, one or two welds There shall be no holes, slag, crater cracks, a weld shall not have undergone, less than welding defects, one or two welds required non-destructive testing, in the provisions of the weld and parts to check the welder's stamp The Unqualified welds shall not be handled without authorization, and the modifications shall be made after the modification process. The number of weld rework in the same part shall not exceed twice.
4, the deformation of components
(1) components in the transport of deformation, the emergence of dead or slow bending, resulting in components can not be installed.
1) components produced due to welding deformation, generally showing slow bending.
2) When the components are to be transported, the mats are unreasonable, such as vertical and horizontal mats, etc., or the stacking of the stacking sites, resulting in dead or slow deformation.
3) component transport due to collision and deformation, generally showing a dead bend.
1) component production, the use of measures to reduce welding deformation.
2) assembly welding, the use of reverse deformation and other measures, the assembly sequence should be subject to the welding sequence, the use of assembly tire, set enough support to prevent deformation.
3) ready to transport and transport, pay attention to the reasonable configuration of the pad.
1) component dead bending deformation, the general use of mechanical correction method. That is, with jack or other tools to correct or supplemented by oxygen acetylene flame baked after correction.
2) structure occurs when the bending deformation occurs, take oxygen acetylene flame heating correction.
(2) steel beam components assembled after the full length of the twist exceeds the allowable value, resulting in poor quality of the installation of steel beams.
1) splicing process unreasonable.
2) Assembly node size does not meet the design requirements.
1) Assemble the assembly to set up the assembly table, as the bottom of the component to be leveling, to prevent warping. Assemble the workstations should be the level of the fulcrum, the welding to prevent the occurrence of welding deformation. Especially the final assembly of the beam or stairway, to adjust the deformation after positioning, pay attention to the size of the node to meet the design, or easy to cause component distortion.
2) their own rigid components, turn the welding before the reinforcement, the components should also be rolled up after leveling, or components can not be corrected after welding.
(3) components from the arch, the value of large or smaller than the design value. Components from the arch value of the hour, after the installation of the beam under the scratch; from the arch when the value is large, easy to produce squeeze surface elevation exceeded.
1) Component size does not meet design requirements.
2) During the erection process, it is not corrected according to the difference between the measured value and the calculated value.
3) a small span of the bridge, from the degree of small, when assembled to ignore.
1) strictly in accordance with the composition of the steel structure to allow the deviation of each step test.
2) During the erection process, the bar and the equipment are finished, and after the construction of the site joints are finished, the upper arch measurement is carried out and the other is adjusted during construction.
3) in the small assembly process, should be strictly controlled cumulative deviation, pay attention to take measures to eliminate the impact of welding shrinkage.
5, steel installation problems
(1) the bottom of the steel column at the foot of the pre-control measures before the steel column hoisting, should strictly control the basis of elevation, accurate measurement, and according to the measured value of the basic surface carefully flat; such as the use of secondary grouting method, Hole (and for the exhaust hole), the use of steel plate will be flat at the bottom of the steel column flat, and in advance according to the design of the height of the column seat steel plate, and then take the secondary grouting.
(2) steel column displacement control measures before pouring concrete foundation, the use of stereotypes chuck will be embedded bolts according to the design location stuck to prevent the displacement of concrete when pouring; column low steel plate reserved hole should be enlarged, And then reserved holes.
(3) column vertical deviation is too large a pre-control measures should be suspended in accordance with the calculation of the hanging point in place, and must use more than two points of the lifting method, lifting should be temporary fixed to prevent deformation of the hoisting; Temporary support should be added in a timely manner; for vertical deviations, correction should be made before fixation.