The general main length of 9m long and threads is 912m.
The HRB-5 range usually allows for B400 and HRB335, HRB500 and HRB500.
As the name implies, round steel is a think, a round long solid rolled forged cold drawn.
Rebar is steel like a plate of rebar belongs to a kind of construction. Rebar is widely used in construction structures.
Unlike rebar, rebar only has the advantage of 9-12, depending on the use of different steel interception thread.
Construction steel bars only Q and Q2321 a commonly used plate. 5 diameters are available in diameter 6.5mm, diameter 8.0mm and 10mm.
In addition to the domestic wire rod of 0mm and outside, is currently drawn wire mesh.
H-beam is a new type of steel for economic construction. H-beam has an economical and reasonable section shape and good mechanical properties.
Compared with ordinary I-beams, H-beams have the advantages of large section modulus, light weight and metal saving, which can reduce the building structure by 30-40%.
As its legs are parallel inside and outside and the leg ends are at right angles, it can be assembled into components, saving 25% of the welding and riveting workload.
Commonly used in large buildings requiring high load bearing capacity and good cross-sectional stability (such as factory buildings, high-rise buildings, etc.), as well as bridges, ships, lifting and transport machinery, equipment foundations, supports, foundation piles, etc.H-beams are divided into hot-rolled H-beams and welded H-beams.
I-beam steel word structure all kinds of steel word and all kinds of I-beam steel, is a type of I-beam steel type of I-beam long steel word. Bracing, machinery, etc.
The edge of ordinary I-beams and light I-beams tapers at an angle from the root to the wing.
The type of I-beam and light I-beam is indicated by Arabic numerals and the waist height is CM.
Z-section steel is a common cold-formed thin-walled section steel, with a thickness of 1.6-3.0mm and a section height of 120-350mm. The processing materials are hot rolled (painted) and galvanized. Z-section steel is usually used in large steel structure plants.
The processing length and hole are produced according to the processing requirements. Supporting products of Z-section steel: color steel tile; Rock wool sandwich board; Floor bearing plate, etc.
(4) C-Steel
The types of C section steel include: galvanised C section steel, hot dip galvanised C section steel, inner bevelled C section steel, roof purlin C section steel, automotive profile C section formwork bracket C section steel, precision C section steel for equipment, etc.
Cold-formed from hot coils, with thin walls, light weight, excellent cross-sectional properties and high strength. Compared with traditional channel steel, the same strength can save 30% material.
It is widely used as purlins and wall beams for steel buildings, and can also be combined to form lightweight roof frames, brackets and other building components. In addition, it can also be used for columns, beams and arms in machinery and light manufacturing.
(1) Light steel structure with suspended beams 35-40kg/㎡.
(2)Light steel structure with or without beam 25-30kg/㎡.
(3)Heavy steel structure with hanging beam 80-100kg/㎡.
(4)Heavy steel structure without lifting beam 60-80kg/㎡.
①If it is a general non-welded steel structure, the forehead pit should be selected from Grade A steel.
②If it is welded structural steel and subjected to static load, B grade steel should be selected; when subjected to dynamic load, C, D, E grade steel structure or special grade steel should be selected according to the ambient temperature of the structure. In this way, the brittle transition temperature of the steel can be lower than the ambient temperature of the structure.
③If laminar tearing will occur in the stressed structural part and the steel plate is thick, it needs to have the ability to resist laminar tearing.
④For joint structures or heavy welded steel structures with complex working conditions and harsh working environment conditions, the steel quality standard requirements should be improved.
①If it is ordinary steel structural steel, the strength grade is generally Q235 or Q345.
②If it is heavy or super heavy structural steel, its strength grade is Q345, Q390 or Q420, or higher.
③If it is a cold-formed thin-walled light steel structure, Grade A is optional for non-welded and Grade B for welded.
Single-storey structural steel
installation is represented by single-storey industrial plant structure installation. Single-storey plants are generally composed of columns, suspension beams, roof racks, skylight racks, purlins, wall racks and various supports. Due to the different forms, sizes, weights and installation elevations of the components, different lifting equipment and lifting methods should be used, and adequate preparations should be made to lay the foundation for the installation works.
① Technical preparation
Preparation of construction organisation design.
Contents include: project overview and characteristics; construction organisation deployment; construction preparation plan; construction procedure and process design; lifting programme; construction schedule; construction site layout plan; supply plan for labour, mechanical equipment, materials and components; quality and safety measures; mode of transport of components, stacking and site management; environmental protection, etc.
Steel structure installation should be carefully read and reviewed the relevant drawings and technical documents before installation, and problems found should be contacted with the owner and design unit in time to solve hidden problems.
Preparation of steel column foundation and supporting surface: before installation, the strength of the foundation concrete must meet the design requirements.
(1) Regular anti-corrosion treatment
The design life of a typical structural steel is 50 years and the probability of damage from overloading is small. The majority of damage to structural steel is due to the reduction in the mechanical and physical properties of the structure caused by corrosion.
Steel design codes have certain requirements for corrosion protection of structural steel that are used for more than 25 years. Therefore, the coating protection on the exterior of the structural steel should meet the requirements for the use of the structural steel.
Generally structural steel require maintenance once every 3 years (painting after removing dirt such as dust and rust from the steel structure). The type and specification of the paint should be the same as the original paint, otherwise the incompatibility of the two paints will bring more harm. The user should plan for regular maintenance and servicing.
Non-metallic coating protection methods are particularly common during later maintenance. The surface of the component should be protected by coatings and plastics to prevent it from coming into contact with the surrounding corrosive media, thus achieving the purpose of corrosion protection.
This method has the advantages of good results, low price, a wide variety of coatings, a wide range of options and high applicability. It is not limited by the shape and size of the component. It can form a film of any shape on the surface of the component and adheres firmly.
When the temperature changes, it can stretch with the component and is easy to use. You can also give the components a beautiful colour.
① It is found that the area of coating surface tarnishing reaches 90%;
② The area of rough, weathered and dry crack on the coating surface reaches 25%;
③ The paint film bulges on the coating and the components are slightly rusted, with an area of 40%;
④ The structural steel affected by high temperature and high temperature shall be equipped with protective plate to protect the coating from high temperature damage.
⑤ Try to avoid the contact between components and substances with corrosive effect, and the contacted shall be cleaned in time.
For the structural steel project that has been used for a period of time, there are inevitably some attachments on its surface, such as rust, dirt and dust; Old paint film, etc.
Before painting the structural steel surface, if these attachments are not completely removed, they can be covered temporarily after painting, but because they play an isolation role, the adhesion between the coating and the component matrix will be seriously reduced, and the paint film will fall off prematurely, which will eventually reduce the corrosion resistance of the surface coating and fail to play the due protective role of the coating.
Therefore, before painting the component surface, the attachments on the structural steel surface shall be thoroughly cleaned.
① Manual rust removal
This method uses steel industries such as scraper, shovel, hammer and steel wire brush to remove dirt by manual knocking shovel and manual grinding with abrasive cloth, sandpaper and grinding wheel, so that the component surface is basically free of oil, rust and burr. This method is often used in structural steel maintenance engineering because of its convenience, simple equipment, low labor cost and not limited by the size of construction site conditions. Its main disadvantages are poor working conditions, low work efficiency, incomplete rust removal and difficult to determine the quality. Therefore, when using this method to remove rust, managers should emphasize the quality requirements.
② Mechanical derusting
In order to improve the derusting quality and work efficiency. To improve the working conditions of construction personnel, pneumatic or electric small equipment has been widely used in the derusting of steel structures.
③ Sand blasting derusting
Sand blasting can be used for rust removal in projects that can be shut down for construction and maintenance. The rust on the roof of steel structure members shall be removed by sand blasting machine to expose the natural color of metal. A better sand blasting machine can automatically screen the fine powder of stone sand, iron sand or iron shot, prevent dust from flying and reduce the impact on the health of the operator. This method removes rust thoroughly. The efficiency is also high, which has been widely used in developed countries. It is a better rust removal method.
④ Remove rust with pickling paste
Special pickling paste for rust removal can be purchased on the market. The use method is to apply the pickling paste on the surface of the component under the coating, with a thickness of about 1 ~ 2mm. After soaking and rolling for an appropriate time, peel off a small piece of pickling paste to check the rust removal. If the metal color is exposed on the component surface, peel off the pickling paste, rinse it with water and completely remove the residual acid. Except for some special cases, this method of rust removal is rarely used at present.
① If the old paint film is firm and complete and the component surface adheres well, the impurities on the surface of the old paint film can be removed with soapy water or dilute alkaline water, washed and wiped dry with clean water, and painted after grinding.
② If most of the old paint film is well attached to the components and some parts need to be removed, in addition to cleaning according to the above methods, it shall also go through the processes of putty, grinding and paint repair, so as to ensure that the place is flat and consistent with the old paint film and the color is the same.
The temperature resistance of steel is poor, and many of its properties change with the temperature rise and fall. When the temperature reaches 430-540 ℃, the yield point, tensile strength and elastic modulus of steel will decrease sharply and lose the bearing capacity. The steel structure must be maintained with refractory materials. It has not been treated with fireproof paint or fireproof paint before.
The fire resistance capacity of buildings depends on the fire resistance performance of building components. In case of fire, its bearing capacity should last for a certain time, so that people can safely evacuate, rescue materials and put out the fire.
The damage of structural steel rust to members is not only the thinning of the effective section of members, but also the “rust pit” on the surface of members. The former reduces the bearing capacity of members and leads to the decline of the overall bearing capacity of steel structures, especially for thin-walled steel and light structural steel.
The latter makes the structural steel produce the phenomenon of “stress concentration”. When the structural steel is under impact load or alternating load, brittle fracture may occur suddenly.
When this phenomenon occurs, there is no sign of deformation, which is not easy to detect and prevent in advance. Therefore, it is very important to monitor the stress, deformation and crack of structural steel and main components.
If the structural steel produces excessive deformation in the service stage, it indicates that the bearing capacity or stability of the structural steel can not meet the service needs.
At this time, the owner shall pay enough attention and quickly organize relevant insiders to analyze the causes of deformation. Put forward the treatment plan and implement it immediately to prevent greater damage to the structural steel project.
① First, drill a round hole with a diameter equal to the thickness of the steel plate at both ends of the crack, and make the tip of the crack fall into the hole. The purpose of this sum is to prevent the crack from continuing to expand.
② The crack between two boreholes shall be welded. During welding, the crack edge can be processed into different types of grooves by gas cutting according to the component thickness, so as to determine the welding quality. When the thickness is less than 6mm, 1-shape (i.e. no groove) shall be used;
when the thickness is greater than 6mm but less than 14mm, V-shape groove shall be used; when the thickness is greater than 14mm, X-shape groove shall be used.
③ After heating the metal around the crack to 200 º C, weld the crack with E43 type (steel plate made of low carbon steel or E55 type (steel plate made of manganese steel) electrode.
④ If the crack is large and has a great impact on the strength of the member, in addition to the welding crack, the metal cover plate shall be connected and reinforced with high-strength bolts.
(1) Stressed bar
Load bearing reinforcement, also known as main reinforcement, refers to the reinforcement configured for basic components such as bending, compression and tension in concrete structure, which is mainly used to bear the tensile stress or compressive stress caused by load. Its function is to make the bearing capacity of components meet the structural functional requirements.
(2) Stirrup
Stirrup refers to the reinforcement used to meet the shear strength of inclined section and connect the main reinforcement and the concrete reinforcement skeleton in the compression area.
It is divided into single leg stirrup, open rectangular stirrup, closed rectangular stirrup, diamond stirrup, polygonal stirrup, well shaped stirrup and circular stirrup. The stirrup shall be determined according to the calculation. The minimum diameter of stirrup is related to the beam height H. when h ≤ 800mm, it shall not be less than 6mm; When H > 800mm, it should not be less than 8mm.
The stirrup at the beam support is generally set at 50mm from the beam side (or wall side). For the reinforced concrete independent beam supported on the masonry structure, no less than two stirrups shall be set within the anchorage length las of the longitudinal stressed reinforcement.
When the beam is integrally connected with the concrete beam or column, the stirrup may not be set in the support.
(3) Erection bar
Erection reinforcement refers to the longitudinal structural reinforcement penetrating the corner of stirrup required to erect stirrup. If the stirrup of the beam is “two limb stirrup”, it is sufficient to mark the form of full-length reinforcement of the middle and upper longitudinal reinforcement, for example: 2 Ф d1.
However, when the stirrup of the beam is “limb stirrup”, the upper reinforcement centrally marked cannot be marked in the form of full-length reinforcement, and the “erection reinforcement” must also be marked.
At this time, the upper longitudinal reinforcement should be marked with “S1” Ф d1+(s2 Ф D2) “in this form, the reinforcement in parentheses is erection reinforcement.
(4) Distribution bar
Most of them appear on the floor. The distribution reinforcement is located at 90 degrees above the load-bearing reinforcement to fix the position of the load-bearing reinforcement, disperse the load on the plate to the load-bearing reinforcement, and prevent cracks perpendicular to the load-bearing reinforcement due to concrete shrinkage and temperature change.
In the shear wall, the longitudinal reinforcement and transverse reinforcement of the wall outside the wall beam and wall column are also called distributed reinforcement.
(5) Others
Structural reinforcement configured due to structural requirements of components or construction and installation needs. Such as waist reinforcement, embedded anchor reinforcement, ring, etc.
(1) Calculate the concrete volume V of a structure and the amount of reinforcement g in the volume, then the steel content of the structure is g / V (kg / m3).
(2) Calculate the total steel consumption g and total building area s of a project, then the steel content of the building is g / S (kg / m2).
Deformed steel bar is commonly known as hot-rolled ribbed steel bar. It belongs to small section steel and is mainly used for the skeleton of reinforced concrete building components. In use, it is required to have certain mechanical strength, bending deformation performance and process welding performance.
Round steel bar is a finished steel bar formed by hot rolling and naturally cooled. It is pressed from low carbon steel and ordinary alloy steel at high temperature. It is mainly used for reinforcement of reinforced concrete and prestressed concrete structures. It is one of the steel varieties used in civil construction engineering.
① Round steel refers to long solid steel with circular section. Its specifications are expressed in millimeters of diameter. For example, “50” means round steel with a diameter of 50 mm. Round steel is divided into hot rolling, forging and cold drawing. The specification of hot rolled round steel is 5.5-250mm.
Among them, 5.5-25mm small round steel is mostly supplied in bundles of straight bars, which is often used as reinforcement, bolts and various mechanical parts; Round steel larger than 25mm is mainly used for manufacturing mechanical parts or seamless steel tube billets.
② Rebar belongs to small section steel, which is mainly used for the framework of reinforced concrete building components. In use, it is required to have certain mechanical strength, bending deformation performance and process welding performance.
The raw material billet for the production of rebar is carbon structural steel or low alloy structural steel treated by sedation melting, and the finished rebar is delivered in hot rolling forming, normalizing or hot rolling state.
① Check whether the brand of reinforcement meets the contract requirements;
② Check whether the product certificate and delivery inspection report meet the national standards;
③ Determine whether the reinforcement quality meets the national standards by observation method (the reinforcement shall be straight and free of damage, and the surface shall be free of crack, oil stain, granular or flake old rust);
④ After the reinforcement mobilization acceptance, fill in the material mobilization acceptance record form and retain the image data;
⑤ Carry out sampling re inspection according to the product sampling plan, issue reinforcement inspection report, and use it only after it is qualified.
① The storage yard of reinforcement shall be hardened and smooth drainage shall be ensured;
② It shall be stacked according to the grade, variety, diameter and manufacturer, and hang a signboard to indicate the origin, specification, variety, quantity and quality inspection status (to be inspected, qualified and unqualified);
③ In order to prevent reinforcement corrosion, the reinforcement that cannot be used in time shall be covered with color strip cloth, and the reinforcement should be set on the ridge wall or square timber.
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