Classification and function of reinforcement mesh
Classification And Function Of Reinforcement Mesh
What is the model and production process of rebar
What Is The Model And Production Process Of Rebar

What Are The Types Of Construction Steel?

Abstract: steel is an important component material of building engineering structure.

The quality of steel has a direct impact on the reliability and durability of building structure and components. So, what are the common building steels? What kind of steel is good for building a house?

Screw thread steel

The general length of deformed steel bar is 9m and 12m. 9m long thread is mainly used for road construction and 12m long thread is mainly used for bridge construction.

The specification range of thread is generally 6-50mm, and national deviation is allowed. Rebar can be divided into three types according to strength: HRB335, HRB400 and HRB500.

Round steel

As the name suggests, round steel is a long solid steel with a circular section, which is divided into hot rolling, forging and cold drawing.


Coil screw is threaded steel coiled together like wire, which belongs to a kind of construction steel. Screw thread steel is widely used in various building structures.

Compared with screw thread steel, the advantage of screw thread steel is that the screw thread steel is only 9-12, and the screw thread can be intercepted at will according to the use needs.

wire rod

There are only two kinds of wire rods Q215 and Q235 for construction steel. The commonly used specifications are 6.5mm in diameter, 8.0mm in diameter and 10mm in diameter.

At present, the largest wire rod in China can reach 30mm in diameter. In addition to being used as the reinforcement of building reinforced concrete, the wire can also be used for wire drawing and mesh wire.


Steel for steel structure

Types of steel for steel structure
(1) H-section steel

H-section steel is a new type of steel for economic construction. The section shape of H-section steel is economical and reasonable, with good mechanical properties.

During rolling, each point on the section extends evenly and the internal stress is small. Compared with ordinary I-section steel, H-section steel has the advantages of large section modulus, light weight and metal saving, which can reduce the building structure by 30-40%;

Because the inner and outer sides of its legs are parallel and the leg ends are right angles, it can be assembled into components, which can save 25% of the workload of welding and riveting.

It is often used in large buildings (such as plants, high-rise buildings, etc.) requiring large bearing capacity and good section stability, as well as bridges, ships, hoisting and transportation machinery, equipment foundation, supports, foundation piles, etc. H-section steel is divided into hot-rolled H-section steel and welded H-section steel.

What are the types of construction steel?
(2) I-beam

I-beam, also known as steel beam, is a long strip of steel with I-shaped section. I-beam is divided into ordinary I-beam and light I-beam. I-beam is widely used in various building structures, bridges, vehicles, supports, machinery, etc.

The flange of ordinary I-beam and light I-beam gradually becomes thinner from the root to the edge, with a certain angle.

The models of ordinary I-beam and light I-beam are represented by Arabic numerals with a waist height of CM.

(3) Z-section steel

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-section steel

The types of C-section steel include: galvanized C-section steel, hot-dip galvanized C-section steel, inner bevel C-section steel, roof purlin C-section steel, automobile profile C-section formwork support C-section steel, precision C-section steel for equipment, etc.

It is processed by hot coil cold bending, with thin wall, light weight, excellent section performance and high strength. Compared with traditional channel steel, the same strength can save 30% of materials.

It is widely used in purlins and wall beams of steel structure buildings, and can also be combined into lightweight roof truss, bracket and other building components. In addition, it can also be used for columns, beams and arms in mechanical and light industry manufacturing.

Steel consumption per square meter of steel structure

(1) The light steel structure has a crane beam of 35-40 kg / ㎡.

(2) Light steel structure with and without beam 25-30 kg / ㎡.

(3) The heavy steel structure has a crane beam of 80-100 kg / ㎡.

(4) Heavy steel structure without crane beam 60-80kg / ㎡.

The purchasing skills of steel for steel structure shall follow the following principles:

(1) Selection of quality grade

① If it is a general non welded steel structure, grade a steel shall be selected for the forehead pit.

② If it is welded structural steel and is under static load, grade B steel shall be selected; In case of dynamic load, grade C, D or E steel structure or special grade steel shall be selected according to the ambient temperature of the structure. In this way, the brittle transition temperature of steel can be lower than the ambient temperature of the structure.

③ If there will be lamellar tear on the stressed structural part and the steel plate is thick, it is necessary to have the ability to resist lamellar tear.

④ It is necessary to improve the standard requirements for steel quality for heavy welded steel structures with complex joint structure or working conditions and poor working environment conditions.

(2) Selection of strength grade

① If it is ordinary steel structure steel, the strength grade is generally Q235 or Q345.

② If it is heavy or overweight structural steel, its strength grade is Q345, Q390 or Q420, or higher.

③ If it is a cold-formed thin-walled light steel structure, class a can be selected for non welding and class B can be selected for welding.

Steel structure construction technology

(1) Installation and construction technology of single-layer steel structure

The installation of single-layer steel structure is represented by the installation of single-layer industrial plant structure. Single storey plant is generally composed of columns, crane beams, roof trusses, skylight frames, purlins, wall frames and various supports. Due to the different forms, sizes, weights and installation elevations of components, different lifting equipment and hoisting methods shall be adopted, and sufficient preparations shall be made to lay the foundation for the installation project.

① Technical preparation

Preparation of construction organization design:

The contents include: Project Overview and characteristics; Construction organization and deployment; Construction preparation plan; Construction procedure and process design; Hoisting scheme; Construction schedule; Layout plan of construction site; Supply plan of labor, mechanical equipment, materials and components; Quality and safety measures; Component transportation method, stacking and site management; Environmental protection, etc.

Before steel structure installation, relevant drawings and technical documents shall be carefully read and reviewed, and problems found shall be timely contacted with the owner and the design unit to solve hidden dangers in time.

Preparation of steel column foundation and supporting surface: before installation, the strength of foundation concrete must meet the design requirements.

Steel structure maintenance

(1) Regular anti-corrosion treatment

Generally, the design service life of steel structure is 50 years, and the probability of damage due to overload is very small. Most of the damage of steel structures is caused by the reduction of structural mechanical and physical properties caused by corrosion.

The code for design of steel structures has certain requirements for the anti-corrosion of steel structures that have been used for more than 25 years. Therefore, the coating protection on the outside of the steel structure shall meet the service requirements of the steel structure.

Generally, the steel structure needs to be maintained once every 3 years (paint shall be applied after cleaning the dust, rust and other dirt in the steel structure). The type and specification of paint shall be the same as the original paint, otherwise the incompatibility of the two paints will bring greater harm. Users shall maintain and maintain regularly in a planned manner.

(2) Method for preventing steel structure from rusting

There are many methods to prevent steel structure from rusting, and the following are usually used.

① The steel structure is made of alloy steel which is not easy to rust

② Chemical oxide layer protection method

③ Metal coating protection method is adopted

④ Non metallic coating protection method

In the later maintenance process, non-metallic coating protection method is particularly commonly used. The component surface shall be protected by coating and plastic to prevent it from contacting with the surrounding corrosive medium, so as to achieve the purpose of anti-corrosion.

This method has the advantages of good effect, low price, many varieties of coatings, wide selection range and strong applicability. It is not limited by the shape and size of components. It can form a film with any shape on the surface of components, and adhere firmly.

When the temperature changes, it can expand and contract with components, which is convenient to use. You can also give components beautiful colors.

(3) Requirements for coating routine maintenance

For maintenance personnel, the daily maintenance of steel structure should first be the maintenance of component surface coating. The quality of coating maintenance directly affects the service life of steel structure.

Therefore, in order to do a good job in daily maintenance, the surface of the steel structure must be kept clean and dry, and the places where the steel structure is easy to accumulate dust (such as steel column base and gusset plate) should be cleaned regularly.

Regularly check the integrity of the protective coating of steel structure, and timely maintain any of the following:

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 steel structure 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.

(4) Rust removal of steel structure surface

For the steel structure 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 steel structure 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 steel structure surface shall be thoroughly cleaned.

What are the types of construction steel?

During the construction of steel structure maintenance project, the surface cleaning mainly includes removing the old paint film. In the process of rust removal, due to the limitation of construction conditions, the general methods include:

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 steel structure 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.

(5) Cleaning of old paint mold on steel structure surface

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.

(6) Regular fire prevention treatment

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.

(7) Regular monitoring

The damage of steel structure 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 steel structures.

The latter makes the steel structure produce the phenomenon of “stress concentration”. When the steel structure 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 steel structure and main components.

(8) Inspection and treatment of deformation of steel structure engineering

If the steel structure produces excessive deformation in the service stage, it indicates that the bearing capacity or stability of the steel structure 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 steel structure project.

(9) Repair method of steel structure crack

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.

Classification of reinforcement for concrete structures

(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.

What Are The Types Of Construction Steel

Selection principle of reinforcement for concrete structure

Firstly, in reinforced concrete structure, reinforcement is the main stressed member (tension compression bending shear torsion), which mainly bears the tensile force and partial shear force generated by bending moment.

Therefore, it must be determined that the area of reinforcement must be sufficient, that is, it must be safe. Similarly, it should also take into account the principles of applicability and economy.

In fact, structural design is to seek a benign balance between conservatism and Appropriateness.

How to calculate the steel content of concrete

(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).

Round bar vs deformed bar
(1) Definition of deformed steel bar

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.

(2) Definition of round reinforcement

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.

(3) Difference between deformed bar and round bar

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.

Code for construction of steel bar

(1) Key points of reinforcement mobilization control

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.

(2) Key points of reinforcement stacking control

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.

(3) Key points of reinforcement processing control

① Reinforcement cutting: ensure the blanking length, check the quality of the cut reinforcement, cut off the part of splitting, head shrinking or serious elbow, and the reinforcement used for mechanical connection must be cut with toothless saw, the end shall be straight, and the top notch shall be free of bevel, horseshoe or flat head.

② Reinforcement bending: when the first-class (smooth round) reinforcement is in tension, the end shall be made into 1800 hooks, and the length of the straight section after bending shall be ≥ 3D;

the end of the stirrup and the hook shall be made into 1350 hooks, and the length of the straight section after bending shall be ≥ 10d and ≥ 75mm (not less than 5D if there is no seismic requirements);

the end of the reinforcement shall be made into 90 ° hooks, and the length of the straight section after bending shall be ≥ 12D (or meet the design requirements).

③ Thread processing: the thread length is one more thread than 1 / 2 of the sleeve length; The tooth shape of silk head is full, without virtual teeth, broken teeth and twisted ribs. The reinforcement must be fully bound, and skipping and missing binding are strictly prohibited; Diameter ≤ ф The reinforcement of 14 must be bound and connected, and electroslag pressure welding is prohibited;

The formwork positioning bar requires that the joint bar shall be reserved before concrete pouring, and it is strictly prohibited to directly weld on the main bar. Reinforcement connection template, including binding, mechanical and welding connection.

④ Binding connection: the overlapping length meets the specification requirements (1.2lae, Lae length: Grade III steel, grade I seismic, c30:40d, c35:37d, c40:33d), and the binding shall not be less than three times.

⑤ Mechanical connection: the number of exposed wire buckles after connection shall not be greater than 1.

(4) Key points of batch processing control of reinforcement

① Check the reinforcement processing blanking sheet

Check whether the model, spacing, size and installation method of reinforcement in the blanking list are consistent with the requirements of drawings and specifications.

② Steel bar rust removal

The oil stain, paint stain, floating skin, rust, etc. on the reinforcement surface must be removed.

③ Reinforcement straightening

The reinforcement must be straightened by mechanical method (cold drawing and elongation are prohibited).

④ Reinforcement cutting, reinforcement bending forming and screw thread processing shall be controlled according to the sample standard.

(5) Key points of reinforcement installation control

① Reinforcement lapping: at the reinforced part, the lapping percentage is 50%, and the lapping length is 1.2lae (LAE length: Grade III steel, grade I earthquake resistance, c30:40d, c35:37d, c40:33d), staggered by 500mm; at the non reinforced part, the lapping rate can reach 100%, but the lapping length is not less than 1.2lae.

② Reinforcement spacing: the reinforcement spacing shall be arranged in strict accordance with the drawing requirements, and the deviation shall be ≤ 10mm;

③ Number of draw hooks: set in strict accordance with the requirements of drawings and specifications without missing binding. Bind firmly and stagger the bending direction;

④ Reinforcement positioning: vertical ladder reinforcement of the wall: the spacing is 1.2m, which can replace the vertical reinforcement of the wall, but it should be one specification larger than the design diameter;

Horizontal ladder reinforcement: control the spacing and position of vertical reinforcement, set a horizontal ladder reinforcement with a height of no more than 300mm from the plate, and use it as the upper positioning reinforcement; Double F-card and plastic cushion block:

control the wall reinforcement section and the thickness of reinforcement protective layer. The double F-card shall be arranged in a quincunx with an interval of 800mm and must be firmly bound with the reinforcement. The plastic cushion block shall be arranged in a quincunx with an interval of 400mm, the spacing of wall reinforcement shall not be greater than 10mm, and the thickness deviation of protective layer shall not exceed ± 5mm.

⑤ Stirrup setting: when longitudinal stressed reinforcement is overlapped and connected, stirrup densification area shall be set within the overlapping range of main reinforcement, The stirrup spacing in the densified area is the smaller of 100mm and 5D (D is the smaller diameter of the overlapping reinforcement); the stirrup at the beam column node must be set as required;

when the shear wall reinforcement replaces the stirrup, all the column reinforcement surrounded by the original stirrup shall be surrounded, and the pull hook shall be set at the intersection with the column longitudinal reinforcement, and the hook angle shall be 135 °.

⑥ Connection setting: the connection part of the longitudinal stressed reinforcement of the column must be set at more than 1 / 3 of the clear height and more than 500mm from the bottom of the beam and slab, the staggered distance of the welding connection position of the adjacent longitudinal reinforcement shall be ≥ 35d and ≥ 500mm, and the staggered distance of the mechanical connection position shall be ≥ 35d.

⑦ Beam reinforcement binding template: the straight anchor length shall not be less than Lae; When bending the anchor, the horizontal section shall not be less than 0.4lae, and the bending section of the bending anchor shall not be less than 15d. When the anchor is anchored into the frame column, the horizontal section shall extend to the inside of the longitudinal reinforcement outside the column;

When the beam height is greater than 450mm, horizontal structural bars shall be set with a spacing of ≤ 200mm; Stirrups shall be configured according to the design requirements. When there are no specific requirements in the design, the stirrup densification area shall be set at the beam column node.

If the length is 500mm and 1.5 times the beam height is larger, the distance between the first stirrup and the node shall be less than 50mm; When the beam reinforcement is set in double rows, the spacing between the upper and lower rows of reinforcement is the larger of reinforcement diameter D and 25mm.

⑧ Top plate reinforcement binding template: the spacing between upper and lower rows of reinforcement meets the design requirements; The hook length of the upper reinforcement shall not be less than the plate thickness h-30mm;

The length of the lower reinforcement anchored into the beam shall not be less than 5D, and shall at least reach the center line of the beam;

When the upper and lower reinforcement is anchored into the shear wall, the length of the reinforcement extending into the shear wall is the greater of 0.35la and 5D, and at least passes through the wall center line. In addition, the upper reinforcement bends down the anchor within the shear wall for 15d;

The upper reinforcement is supported by horse stool iron, and the erection reinforcement is used to control the thickness of reinforcement protective layer, and the lower reinforcement is supported by concrete cushion block with a spacing of 800mm-1000mm; At the lifting plate, the intersection length of reinforcement at the variable section shall be at least la.

⑨ Stair reinforcement binding template: the spacing between upper and lower rows of reinforcement meets the design requirements;

The upper longitudinal reinforcement shall be anchored into the ladder beam, and the length extending into the ladder beam shall not be less than 0.35la, and can be bent downward at least after extending to the opposite side of the beam, and the length of the straight section of the hook shall not be less than 15d; The lower longitudinal reinforcement shall be anchored into the ladder beam, and the length extending into the ladder beam shall not be less than 5D, and at least extend to the center line of the lintel;

When the upper longitudinal reinforcement of the ladder board is set as non through reinforcement (set at both ends of the ladder board), the length of the longitudinal reinforcement in the ladder board shall be at least 1 / 4ln (LN is the length of the ladder board).

(6) Control points of reinforcement binding sample section

① Beam: the reinforcement length of the upper row of additional reinforcement shall be configured according to the design requirements. When there are no specific requirements in the design, it is 1 / 3 of the beam span, the reinforcement length of the second row of reinforcement is 1 / 4 of the beam span, and the span is the larger of the adjacent beam span.

② Slab: when there is no beam below the slab and there is masonry on the upper part, additional reinforcement shall be set directly below the masonry, the diameter of the additional reinforcement shall not be less than 14mm, and the extension length after intersection shall not be less than LA.

(7) Key points for protection and control of finished reinforcement

① Finished product protection after reinforcement processing

The qualified wire heads shall be covered with protective caps to prevent corrosion and pollution. They shall be classified and stacked neatly according to the specifications, and shall be transported to the construction site for use.

② Finished product protection during binding

During the binding of wall reinforcement, a temporary frame shall be erected, and it is not allowed to step on the reinforcement. The deformed reinforcement shall be rectified before the formwork is erected.

③ Finished product protection during concrete pouring

Before pouring concrete, the vertical reinforcement of walls and columns shall be tightly wrapped with colored strip cloth and plastic strip, and the contaminated reinforcement shall be wiped off with cotton wire or steel wire brush in time after concrete pouring.

④ Finished product protection of slab reinforcement

After the plate reinforcement is bound, a special person shall be assigned to take care of it. It is strictly prohibited for constructors to step on the reinforcement. During concrete pouring, a temporary passage shall be set up with a reinforced stirrup springboard or a wooden springboard shall be laid on the reinforcement net.

During pouring, a special person shall be assigned to supervise, control the evacuation time of the springboard, and timely restore the deformed and displaced reinforcement. Madeng iron is shown in the right figure.

During concrete pouring, if machines and tools such as distributor are used, it is strictly prohibited to directly frame them on the top plate reinforcement.

It is required to make supports separately and place them on the supports to avoid damage to the bound reinforcement.

Maintenance skills of building reinforcement

(1) Select appropriate site and warehouse

The steel storage site or warehouse shall be in a clean place with smooth drainage, away from factories and mines that produce harmful gas or dust. Weeds and all sundries shall be removed on the site to keep the steel clean. The warehouse shall be ventilated in sunny days, closed in rainy days to prevent moisture, and always maintain a suitable storage environment.

(2) Reasonable stacking, first in first out

The principle of stacking is to stack according to varieties and specifications under the condition of stable stacking and ensuring safety.

Different kinds of materials shall be stacked separately to prevent confusion and mutual corrosion.

(3) Packaging and protective layer of protective materials

Steel shall be coated with various preservatives or other plating and packaging before leaving the factory, which is an important measure to prevent material corrosion, which can prolong the storage period of materials. During transportation, loading and unloading, attention shall be paid to protection and shall not be damaged.

(4) Keep the warehouse clean and strengthen the maintenance of materials

Before warehousing, materials shall be protected from rain or impurities, and materials that have been exposed to rain or contaminated shall be wiped by different methods according to their properties;

The materials shall be inspected frequently after warehousing to ensure that the rust layer is removed in time.

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