What are the types of construction steel

Summary: Steel is an important component material of the structure of the construction project, how the quality of steel, the reliability and durability of the structure and components of the house has a direct impact. So, what are the common construction steel? What steel is good for building houses? Below, take a look to understand it! Construction steel classification and use of rebar rebar of the general length of 9m, 12m, 9m long thread is mainly used for road construction, 12m long thread is mainly used for bridge construction. The specification range of the thread is generally 6-50mm, and the state allows deviation. According to the strength of the rebar, there are three types of HRB335, HRB400 and HRB500.

Circular steel, as the name suggests, round steel is a solid strip of steel with a round cross-section, divided into hot-rolled, forged and cold-drawn three kinds.

The coiled coil is a rebar that is coiled together like a wire rod, and is a type of steel used in construction. Rebar is widely used in a variety of building structures, coil compared to the advantages of rebar is rebar only 9-12, coil can be used according to the need for arbitrary interception.

Wire construction steel coil only Q215, Q235 two kinds, generally often used specifications have a diameter of 6.5mm, diameter 8.0mm, diameter 10mm, at present, China's largest coil can reach a diameter of 30mm. wire in addition to used as a reinforcing concrete reinforcement of the building, but also can be applied to the wire for wire drawing, wire mesh with the wire.

Steel structure steel steel structure steel types (1) H-beam

H-beam is a new type of economic construction steel. H-beam cross-section shape is economically rational, good mechanical properties, rolled cross-section on the extension of the points of a more uniform, internal stress is small, compared with the ordinary I-beam steel, with a large cross-section modulus, lightweight, the advantages of saving metal, the construction of the structure can be reduced by 30-40%; And because of its legs parallel to the inside and outside of the leg, the leg end is right angle, assembled into components, can save welding, riveting workload up to 25%. Commonly used in the requirements of large capacity, cross-section stability of large buildings (such as factories, high-rise buildings, etc.), as well as bridges, ships, lifting and transportation machinery, equipment foundations, brackets, foundation piles, etc. H-beam is divided into hot-rolled H-beam and welded H-beam two kinds of steel.

(2) I-beam

I-beam, also known as steel beams, is the cross-section of the I-beam long steel. I-beam is divided into ordinary I-beam and lightweight I-beam. I-beams are widely used in various building structures, bridges, vehicles, brackets, machinery and so on. Ordinary I-beam steel and light I-beam steel wing edge from the root to the side of the gradually thinning, there is a certain angle, ordinary I-beam steel and light I-beam steel model is with its waist height centimeters of Arabic numerals to express.

(3) Z-beam

Z-beam is a common cold-formed thin-walled steel, the thickness is generally between 1.6-3.0mm, the section height is mostly between 120-350mm. Processing materials are hot-rolled (painted), galvanized. z-beam is usually used in large-scale steel structure plant. Processing length and hole for the production of processing requirements. z steel supporting products: color steel tiles; rock wool sandwich panels; floor slabs and so on.

(4) C-beam

The types of C-beam are: galvanized C-beam, hot-dip galvanized C-beam, inner beveled edge C-beam, roof purlin C-beam, automobile profile C-beam template support C-beam, precision C-beam for equipment. Processed by hot rolled plate cold bending, thin wall, light weight, excellent section performance, high strength, compared with the traditional channel steel, the same strength can save 30% of the material. Widely used in steel structure building purlins, wall beams, can also be self-assembled into lightweight roof racks, brackets and other building components. In addition, it can also be used for columns, beams and arms in mechanical light manufacturing.

Steel consumption per square meter of steel structure (1) light steel steel structure has crane beam 35-40_/_.

(2) Light steel steel structure with craneless beam 25-30_/_.

(3) Heavy steel steel structure has crane beam 80-100_/_.

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

Steel structure steel purchasing skills steel structure steel selection follow the following principles:

(1) the choice of quality grade

①If the general non-welded steel structure, the amount of pit selection of A-grade steel.

② If it is a welded structural steel, and is the static load, then it should be selected B grade steel; if it is the dynamic load, then it should be based on the structure of the ambient temperature, the selection of C, D or E grade steel structure, or special grade steel. In this way, the brittle transition temperature of steel can be lower than the ambient temperature of the structure.

3) If there will be laminar tearing stresses on the structural parts, and the steel plate is thick, it needs to be resistant to laminar tearing.

④For the node structure or heavy welded steel structure with complicated hand conditions and harsh working environment conditions, the standard requirements for steel quality need to be raised.

(2) Selection of strength grade

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

②If it is a heavy or super-heavy steel structure steel, then its strength grade is Q345, Q390 or Q420, or higher grade.

③If it is cold-formed thin-walled lightweight steel structure, then you can choose Grade A for non-welded and Grade B for welded.

Steel structure construction process (1) single-story steel structure installation construction process

Single-story steel structure installation project is represented by single-story industrial plant structure installation. The single-story factory building is generally composed of columns, crane beams, roof racks, skylight racks, purlins, wall racks and various types of supports and other components. Due to the form of components, size, weight, installation elevation and so on, should use different lifting equipment and lifting methods, and make adequate preparations for the installation project to lay the foundation.

①Technical preparations

Preparation of the construction design:

Contents include: project overview and characteristics; construction organization and deployment; construction preparation plan; construction procedures and process design; lifting program; construction schedule; construction site layout; labor, machinery and equipment, materials and components supply plan; quality measures and safety measures; component transportation Methods, stacking and site management; environmental protection, etc.

Before steel structure installation, relevant drawings and technical documents should be carefully read and examined, and problems should be found to be promptly contacted with the owner and the design unit, so as to solve the hidden dangers in time.

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

Steel structure maintenance (1) regular anticorrosion treatment

General steel structure in the design of the service life of 50 years, in the use of the steel structure due to overloading the use of the destruction of the chances are very small. Most of the steel structure damage is caused by rust and corrosion resulting in the reduction of structural mechanical properties and physical properties, "Steel Structure Design Code" for the use of more than 25 years of steel structure corrosion has certain requirements. Therefore, it is required that the external painting protection of steel structure should meet the use requirements of steel structure, and in general, the steel structure should be maintained for 3 years (clean up the dust, rust and other dirt in the steel structure and then brush the paint). Paint varieties, specifications should be the same as the original paint, otherwise the two paints can not reach the compatibility will bring more harm, the user should do regular maintenance and maintenance in a planned manner.

(2) Methods to prevent steel structure from rusting

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

①Adopting alloy steel which is not easy to rust to make steel structure

②Chemical oxidizing layer protection method

③Adopting metal plating protection method

④Non-metallic coating protection method

In the later process of maintenance and repair, the non-metallic coating protection method is especially commonly used. In the component surface using paint, plastic protection, not to make contact with the surrounding corrosive medium, in order to achieve the purpose of anti-corrosion. This method is effective, inexpensive, and more varieties of coatings, for a wide range of choices, strong applicability, not subject to the shape and size of the component limitations, with any shape of the surface of the component into a film, firmly attached, temperature changes can also be with the component expansion and contraction, easy to use. It can also give the member a beautiful color.

(3) Requirements for routine maintenance of coating

For the maintenance personnel, the routine maintenance of steel structure should be the first maintenance of the surface coating of the members. The good or bad maintenance of the coating directly affects the service life of the steel structure. Therefore, to do a good job of daily maintenance must keep the surface of the steel structure clean and dry, and the places where the steel structure is easy to accumulate dust (e.g., at the foot of the steel column, node plate) should be cleaned regularly.

Regularly check the intact condition of the protective coating of the steel structure, where one of the following should be maintained in time:

1) 90% of the surface of the coating is found to have lost its luster;

2) 25% of the surface of the coating is rough, weathered and cracked;

3) 40% of the surface of the coating is covered by the paint film bumps and the components have a slight area of rust;

4) 40% of the surface is exposed to high temperatures and high temperature, which is the most important factor for the maintenance of the steel structure.

④The steel structure parts affected by high temperature and high temperature should be equipped with guard plate to protect the coating from high temperature damage.

⑤ Try to avoid contact between components and substances with erosive effect, and those already in contact should be cleaned up in time.

(4) Descaling of steel structure surface

For the steel structure project which has been used for a period of time, some attachments inevitably exist on the surface, such as rust, dirt, dust, old paint film and so on. Before painting the surface of steel structure, if these attachments are not removed thoroughly, although they can be temporarily covered up after painting, but because they play a role in isolation, making the adhesion between the coating and the component substrate is seriously reduced, and the paint film will fall off prematurely, which ultimately leads to a reduction in the resistance of surface coating to rust and corrosion, and does not play the role of the coating should be protected. Therefore, before painting the surface of the component, the surface of the steel structure should be thoroughly cleaned of the adherents.

In the construction of steel structure maintenance project, the surface cleaning work mainly includes removing the old paint film. In the process of rust removal, due to the limitations of the construction conditions generally used methods are:

①Manual descaling

This method is to use scrapers, spatulas, hand hammers, steel wire brushes and other steel workers Xing, by hand knocking shovels, as well as sand cloth, sandpaper, and grinding wheels to remove dirt by hand, so that the surface of the component basically reach no oil, no rust, no burrs. This method is often used in the steel structure maintenance project to remove rust due to the convenience and ease of use, the required equipment is simple, the labor cost is low, and is not subject to the limitations of the size of the construction site conditions. Its main disadvantages are poor labor conditions, low efficiency, incomplete descaling, and the quality is not easy to determine. Therefore, when using this method to remove rust, the managers should emphasize the quality requirements.

②Mechanical descaling

In order to improve the quality and efficiency of descaling. In order to improve the quality and working efficiency of descaling, and to improve the working conditions of the construction personnel, a large number of wind or electric small-scale equipments have been adopted in the descaling work of steel structure nowadays.

③Sandblasting descaling

In the construction and maintenance projects that can be stopped, sandblasting descaling can be used. Through the sand blasting machine will be the steel structure components of the sky surface of the rust removal clean, revealing the original color of the metal. The better sand blasting machine can automatically sieve away the fine powder of the sprayed stone yellow sand, iron sand or iron shot, and prevent the dust from flying, reducing the impact on the operator's health. This method removes rust thoroughly. Efficiency is also higher, in developed countries has been widely used, is a better method of rust removal.

4 with pickling cream rust

The market can be purchased to special de-rust pickling cream, the use of pickling cream coated with the surface of the components under the Department, the thickness of about 1 ~ 2mm, soak and roll wet the appropriate time, peel off a small slice of pickling cream to check the situation of rust, if the surface of the components to reveal the color of the metal, then the pickling cream peeled off, rinse with water to completely remove the residual acid. In addition to some special circumstances, this method of rust removal has been rarely used.

(5) The cleaning of old paint mold on the surface of steel structure

①If the old paint film is solid and complete, the surface of the component is well adhered, soapy water or dilute alkaline water can be used to remove the impurities on the surface of the old paint film, and then wipe it dry with water, and then paint can be applied after grinding.

② such as most of the old paint film and components attached to good, local removal, in addition to the above method of cleaning, should also be putty, sanding, refinishing and other processes, and strive to achieve the old paint film with the same flat, the same color.

(6) regular fire treatment

Steel temperature resistance is poor, many of its properties change with the temperature rise and fall, when the temperature reaches 430-540 ℃, the yield point of steel, tensile strength and modulus of elasticity will drop dramatically, loss of load-bearing capacity. Fire-resistant materials must be used for the necessary maintenance of the steel structure. It has not been previously treated with fire-resistant coatings or fire-resistant paints. The fire resistance of the building depends on the good or bad fire resistance of the building components, and its carrying capacity should be able to continue for a certain period of time when a fire occurs, so that people can safely evacuate, rescue materials and extinguish the fire.

(7) Regular monitoring

Steel structure rust damage to members not only manifested in the effective cross-section of the members of the thinning, but also manifested in the surface of the members of the "rust pit". The former makes the component bearing capacity decrease, leading to the decline of the overall bearing capacity of the steel structure, thin-walled steel and light steel structure is particularly serious. The latter makes the steel structure produce "stress concentration" phenomenon, when the steel structure in the impact load or alternating load, may suddenly occur brittle fracture. There is no sign of deformation when this phenomenon occurs, and it is not easy to detect and prevent it beforehand. For this reason, it is very important to monitor the stress, deformation and cracking of steel structures and major components.

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

If the steel structure produces excessive deformation in the use stage, it indicates that the bearing capacity or stability of the steel structure can no longer meet the use needs. At this time, the owner should pay enough attention and quickly organize the relevant industry professionals to analyze the cause of deformation. Put forward the management program and implement it immediately to prevent the steel structure project from producing greater damage.

(9) Steel structure crack repair method

①First in the crack at each end of a circular hole with a diameter equal to the thickness of the steel plate drilling, and make the tip of the crack tribal into the hole, so and the purpose is to prevent cracks continue to expand.

② The crack between the two drilled holes to be welded, welding can be based on the thickness of the component will be cracked edge with gas cutting processed into different types of bevels to determine the quality of welding. When the thickness is less than 6mm, the use of 1-shaped (i.e., not open bevel) when the thickness is greater than 6mm and less than 14mm, the use of V-shaped bevel; when the thickness is greater than 14mm need to use X-shaped bevel.

③The metal around the crack is heated to 200_C, and then the crack is welded with E43 type (the steel plate material is mild steel or) E55 type (the steel plate material is manganese steel) welding rod.

④If the crack is large, the strength of the member is greatly affected, in addition to weld the crack, should also be metal cover plate reinforced with high-strength bolt connection.

Reinforced concrete structure with reinforced concrete structure with reinforced steel classification (1) stressed bar

Stressed bar, also known as the main bar, refers to the concrete structure, for bending, compression, tension, and other basic components configured to withstand tensile or compressive stresses caused by the load of the steel bar, its role is to make the bearing capacity of the component to meet the structural function requirements.

(2) hoop

Hoop refers to the shear strength of diagonal cross-section to meet, and linking the main force and compression zone of the mixed reinforcement skeleton of the steel. Single limb hoops, open rectangular hoops, closed rectangular hoops, rhombic hoops, polygonal hoops, tic-tac-toe hoops and round hoops. Hoop should be determined according to the calculation, the minimum diameter of the hoop with the beam height h, when h_800mm, should not be less than 6mm; when h>800mm, should not be less than 8mm. beam support at the hoop is generally from the beam side (or wall side) 50mm from the beginning of the set. Supported on the masonry structure of reinforced concrete independent beam, in the longitudinal force reinforcement of the anchorage length Las range should be set not less than two hoops, when the beam is connected with the concrete beams or columns as a whole, the support may not be set in the hoops.

(3) Racking bars

Racking bars refer to the longitudinal structural reinforcement through the corners of the hoop bars required to erect the hoop bars. If the beam of the hoop is "two-limbed hoop" beam, the centralized labeling of the longitudinal bars in the upper longitudinal bar in the form of longitudinal bars is sufficient, for example: 2Фd1. However, when the beam of the hoop is "four-limbed hoop", the centralized labeling of the upper part of the reinforcement can not all be marked as longitudinal bars. The form, must be "frame bar" also marked on the upper longitudinal bar should be labeled "s1Фd1 + (s2Фd2)" this form, round brackets inside the bar for the frame bar.

(4) distribution bar

Most of them are in the floor, distribution bar is in the force bar above the 90 degrees to fix the position of the force bar, and the plate load dispersed to the force bar, but also to prevent the contraction of the concrete and temperature changes in the direction of the perpendicular to the force bar to produce cracks. In the shear wall, wall beams and wall columns outside the wall longitudinal reinforcement transverse reinforcement is also known as the distribution of tendons.

(5) Other

The structural reinforcement configured due to the structural requirements of components or construction and installation needs. Such as waist reinforcement, pre-buried anchorage, ring, etc..

Concrete structure with reinforcing steel selection principle first, reinforced concrete structure, steel is the main force components (tension pressure bending shear torsion), mainly to withstand bending moments generated by the tension and part of the shear force, so it is necessary to determine the area of steel must be enough, that is to say, to be safe, the same, but also to take into account the applicability of the principle of economy, structural design in fact, is to be in the conservative and appropriate to seek a virtuous The balance.

How to calculate the steel content of concrete (1) calculate the volume of concrete of a structure V, and the volume of steel within the volume of G, then, the steel content of the structure is G/V (kg/m3).

(2) Calculate the total amount of steel used in a project, G, and the total floor area, S. Then, the steel content of the building is G/S (kg/m2).

Round steel bar vs. rebar (1) definition of rebar

Rebar is the common name for hot-rolled ribbed steel bar, which belongs to the small section steel steel, and is mainly used for the skeleton of reinforced concrete building components. In use requires a certain mechanical strength, bending deformation properties and process welding properties.

(2) the definition of round reinforcing bars

Round reinforcing bars are hot rolled and naturally cooled finished steel bars, made of mild steel and ordinary alloy steel pressed at high temperatures, mainly used for reinforced concrete and pre-stressed concrete structure reinforcement, is one of the steel varieties of civil engineering and construction projects with more use.

(3) the difference between rebar and round steel bar

①round steel is a solid long steel with a round cross-section. Its specifications are expressed in millimeters of diameter, such as "50" that is, the diameter of 50 millimeters of round steel round steel is divided into hot-rolled, forged and cold-drawn three kinds. Hot rolled round steel specifications for 5.5-250 mm. Among them: 5.5-25 millimeters of small round steel mostly in straight bundles of supply, commonly used for reinforcing bars, bolts and a variety of mechanical parts; greater than 25 millimeters of round steel, mainly used in the manufacture of mechanical parts or for seamless steel pipe billet.

② Rebar belongs to the small section steel steel, mainly used for reinforced concrete building components of the skeleton. In use requires a certain degree of mechanical strength, bending deformation properties and process welding performance. Production of rebar raw material billet for the sedentary melting treatment of carbon structural steel or low alloy structural steel, finished steel bars for hot rolled forming, normalized or hot rolled state delivery.

Building reinforcing steel construction specifications (1) rebar into the field control points

①to check whether the brand of rebar is in line with the contract requirements;

②check the product certification, factory inspection report whether it is in line with the national standards;

③ through the observation method to determine the quality of rebar in line with the national standards (the steel bar should be straight, undamaged, the surface shall not have cracks, oil, particles or flakes of old rust). (the surface should not have cracks, oil stains, granular or flaky old rust);

④After the acceptance of rebar, fill in the Material Acceptance Record Sheet and keep the image data;

⑤ Conduct the sample re-inspection in accordance with the sampling program of the product, and issue the rebar inspection report, and use it after it passes the test.

(2) rebar stacking control points

① rebar stacking site should be hardened, and ensure smooth drainage;

② should be according to the level, variety, diameter, manufacturer palletizing, and hang signs, indicating the origin, specifications, varieties, quantities, quality inspection status (to be inspected, qualified, unqualified);

③ in order to prevent corrosion of rebar, can not be timely! Use of reinforcing steel should be covered with colored cloth, and reinforcing steel should be set on the ridge wall or square wood.

(3) Steel processing control points

①Steel cutting: to ensure that the length of the material, check the quality of the cut off steel, will split, head or serious elbow part of the removal of the mechanical connection of the steel must be used to cut toothless saws, the end of the end of the straight, the top of the incision without slanting mouth, horseshoe mouth or flat head.

② steel bending: a (light round) steel bar tensile end made of 1800 hooks, the length of the straight section after the bend ≥ 3d; hoop bar and pull the hooks at the end of the 1350 hooks, the length of the straight section after the bend ≥ 10d and ≥ 75mm (no seismic requirements of no less than 5d); 90 ° hooks at the end of the steel bar, the length of the straight section after the bend ≥ 12d (or to meet the design requirements).

3 silk buckle processing: silk buckle length than 1/2 sleeve length more than a silk buckle; silk head teeth full, no false teeth, broken teeth, no twisted ribs. Reinforcement binding must be full binding, strictly prohibit jumping binding, leakage binding; diameter ≤ ф14 rebar must be connected by binding, prohibit the use of electroslag pressure welding; template locating bar required to be reserved for insertion of reinforcement before the concrete is poured, and prohibited directly welded to the main bar. Reinforcing bar connection samples, including tying, mechanical and welding connections.

④Tied connection: lap length meets the specification requirements (1.2Lae, Lae length: Grade 3 steel, Grade 1 seismic, C30: 40d, C35: 37d, C40: 33d), and tied no less than three times.

⑤Mechanical connection: the number of exposed wire buckles after connection is not more than 1.

(4) Control points of batch processing of reinforcement bars

①Check the steel processing order

Check whether the model, spacing, size and installation method of reinforcement bars in the order are consistent with the drawings and specification requirements.

② steel rust

The surface of the steel bar oil, paint and pumice, rust, etc. must be removed.

③ steel straightening

steel straightening must be mechanically straightened (prohibit cold elongation).

④Steel cutting, steel bending and molding, wire fastening processing are controlled in accordance with the sample standards.

(5) Reinforcing steel installation control points

①Reinforcing steel lap: set up in accordance with 50% lap percentage in the reinforced part, lap length 1.2Lae (Lae length: Grade 3 steel, Grade 1 seismic, C30: 40d, C35: 37d, C40: 33d), staggered by 500mm; in the non-reinforced part, the lap rate can be up to 100% but the lap length is not less than 1.2Lae.

② steel spacing: steel spacing is arranged in strict accordance with the requirements of the drawings, deviation ≤ 10mm;

③ the number of hooks: set up in strict accordance with the drawings and specifications, there shall be no leakage of binding phenomenon, binding is firm and the direction of the bends need to be staggered arrangement;

④ rebar positioning: vertical ladder reinforcement of the wall: the spacing of 1.2m arrangement, may be Instead of wall vertical reinforcement, but to be larger than the design diameter of a specification; Horizontal ladder bar: control the spacing and location of the vertical bar, set up a horizontal ladder bar, the height from the plate is not more than 300mm, as a turnover of the upper layer of positioning bar; Double F card, plastic pads: control of the wall reinforcement cross-section and the thickness of the protective layer of steel reinforcement, double F card spacing 800mm flower-shaped arrangement and must be tied firmly with the reinforcement, plastic pads spacing 400mm flower-shaped arrangement, wall reinforcement cross-section and protective layer thickness, double F card spacing 800mm flower-shaped arrangement and must be tied firmly, plastic pad spacing 400mm flower-shaped arrangement. 400mm plum blossom arrangement, wall reinforcement spacing shall not be greater than 10mm, the protective layer thickness deviation shall not exceed ±5mm.

⑤ Hoop setting: longitudinal stress reinforcement lap connection, set up hoop encrypted area within the range of the main bar lap, encrypted area hoop spacing of 100mm and 5d (d is the smaller diameter of the lap reinforcement) the lesser; beam-column node hoops must be set in accordance with the requirements; Shear wall reinforcement instead of hoop reinforcement, the original hoop reinforcement surrounded by all the column reinforcement, and column longitudinal reinforcement at the intersection of the set hook, the bending angle of all 135 °.

6 Connection setup: column longitudinal reinforcement connection must be set above 1/3 of the clear height and above 500mm from the bottom of the beam and plate, adjacent longitudinal welding connection position staggered distance ≥ 35d and ≥ 500mm, mechanical connection position staggered distance ≥ 35d.

7 Beam reinforcement strapping samples: Straight anchors length is not less than Lae; bending anchors, horizontal section of no less than 0.4 Lae, curved anchor bending section is not less than 15d, anchored to the frame column, the horizontal section needs to extend to the column outside longitudinal reinforcement inside; beam height is greater than 450mm, set the level of structural reinforcement, spacing ≤ 200mm; should be configured according to the design requirements of the hoop. When there is no specific design requirements, beam-column node set hoop encryption area, the length of 500mm and 1.5 times the beam height of the larger, the first hoop distance from the node is less than 50mm; beam reinforcement double-row set up, the upper and lower rows of reinforcement spacing for the diameter of the steel bar d and the larger of 25mm.

8 top plate reinforcement binding sample: the spacing of the upper and lower rows of reinforcement in accordance with the design requirements; the length of the upper layer of reinforcement bending hook is not less than the thickness of the plate h-30mm; the lower layer of reinforcement anchored into the beam in the length of not less than 5d, and at least to the beam center line; on the lower layer of reinforcement anchored into the shear wall, the length of the steel bar extending into the shear wall for the larger of the length of the 0.35 La and 5d, and at least over the center line of the wall, and the other upper layer of reinforcing bar in the shear wall downward bending anchor. Shear wall downward bending anchor 15d; upper reinforcement using bench iron support, and the use of racking tendons to control the thickness of the protective layer of reinforcement, the lower reinforcement using concrete pads support, spacing 800mm-1000mm; lifting plate, reinforcement in the variable cross-section intersection length of at least La.

9 staircase reinforcing bar binding samples: upper and lower rows of reinforcing bar spacing in accordance with the design requirements; upper longitudinal reinforcement anchored into the stair beam, extending into the stair beam length of not less than La. The upper longitudinal bar is anchored into the ladder beam with a length of not less than 0.35La, and at least extends to the opposite side of the beam before bending down, and the length of the straight section of the bending hook is not less than 15d; the lower longitudinal bar is anchored into the ladder beam with a length of not less than 5d and at least extends over the beam centerline; when the upper longitudinal bar of the ladder plate is set as a non-penetrating bar (set at the ends of the ladder plate), the longitudinal bar length in the ladder plate is at least 1/4Ln (Ln is the length of the ladder plate).

(6) The control points of the sample section of reinforcement tying

①Beam: the reinforcement length of the upper row of reinforcement should be configured according to the design requirements, when the design has no specific requirements for 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 one of the neighboring beam span.

② plate: no beam below the plate and the upper part of the masonry, the masonry is required to set up additional reinforcement in the area directly under the masonry, additional reinforcement diameter of not less than 14mm, the intersection of the outstretched length of not less than La.

(7) reinforcing steel finished product protection control

1) reinforcing bar processing is completed after the protection of the finished product

The inspection of qualified fillet covered with a good protective cap to prevent corrosion, Pollution, according to the specifications of the classification code neatly, to be transported to the construction site to use.

② Tying process of finished product protection

Wall reinforcement should be set up when tying a temporary frame, not allowed to step on the steel, the deformation of the steel should be rectified before the template support.

③Protection of finished products when pouring concrete

Before pouring concrete, the vertical bars of walls and columns should be wrapped tightly with colorful strips of cloth and plastic strips, and after pouring concrete, the contaminated reinforcement bars should be wiped clean with cotton or steel wire brush in time.

④The finished product protection of plate reinforcement

After the completion of plate reinforcement binding, set up a special person to watch over, and forbid the construction workers to step on the reinforcement. Concrete pouring with steel stirrups springboards set up temporary channels or laying wooden springboards on the reinforcing steel network, pouring assigned to supervise, control the springboard evacuation time, and timely restoration of deformed and displaced reinforcement, Madden Iron, as shown in the figure on the right.

Concrete pouring, such as the use of fabric machines and other machinery, it is strictly prohibited to be placed directly on the top plate reinforcing steel, requiring a separate production of brackets, will be placed on the bracket, to avoid damage to the already tied reinforcing steel.

Construction steel maintenance skills (1) choose a suitable site and warehouse

Storage of steel site or warehouse, should be selected in a clean, clean, well-drained place, away from the production of harmful gases or dust of the factories and mines. Site to remove weeds and all the debris, keep the steel clean. The warehouse requires attention to ventilation on sunny days, rainy days, attention to close the moisture-proof, and often maintain a suitable storage environment.

(2) reasonable stacking, first-in-first-out

The principle of stacking is required in the palletization of solid, to ensure the safety of the conditions to do according to the varieties and specifications of the pallet. Different varieties of materials should be palletized separately to prevent confusion and mutual corrosion.

(3) protection of packaging and protective layer of materials

Steel should be coated with various types of anticorrosive agents or other plating and packaging before leaving the factory, which is an important measure to prevent corrosion of the material, which can extend the storage period of the material. In the transportation loading and unloading process must pay attention to the protection, can not be damaged.

(4) to keep the warehouse clean, strengthen the maintenance of materials

Materials in the warehouse before the attention to prevent rain or mixed impurities, the material has been rained or soiled according to its nature to use different methods to wipe clean; materials into the warehouse should be frequently checked to ensure that timely removal of the corrosion layer.