Concrete Reinforcing Welded Steel Mesh With Ribbed A393/A381/A252/A193/A142/A98 Standard

concrete reinforced Welded steel mesh is a kind of welded steel mesh for reinforcing bar net reinforced concrete welded by coldrolled ribbed steel bars or cold-rolled bars. It is a good and efficientmaterial for concrete distribution. Its appearance is of great significance forimproving the efficiency of building construction, structural quality, safetyand reliability, and changing the traditional construction methods. It can beused for reinforcing bars and reinforced bars in reinforced concretestructures. In order to standardize the production and application of thismaterial and promote the improvement of the industrial level of China'sconstruction industry, the standard YB/T076 - 1995 of this industry has beenformulated.

This standard is defined as follows:

1.2 cold rolled surface steel bar: the surfacesteel bar of hot rolled disc is cold-rolled or cold drawn after reducing thediameter. The cross section is usually round.

1.3 longitudinal reinforcement: rebar arranged inparallel with the direction of steel mesh manufacturing.

1.4 transverse reinforcement: a steel barperpendicular to the direction of the steel mesh manufacturing.

1.5: the spacing between adjacent reinforced steelmesh in center line distance, the two bars, the center line of two steelcontact points tangent.

1.6 double root steel bars: two steel bars of thesame type and the same diameter that are close together in the steel mesh.

1.7: the length of the longitudinal and transversesteel bar netting beyond the outermost transverse and longitudinalreinforcement center line length for double reinforced, the center line of twosteel contact points tangent.

1.8 the length of the steel mesh: the size of thelong side of the steel mesh (independent of the manufacturing direction).

1.9 the width of the steel mesh: the size of theshort side of the steel mesh (independent of the manufacturing direction).

Material

2.1, the steel mesh shall be made of GB/T 550, 5504mm cold rolled ribbed steel bars with diameters of 4mm to 12mm, and the LG550grade cold rolled steel bars with diameter of 4mm to 12mm according to table a.

The code name of the cold rolled ribbed steel baris LL550 (L, L as "cold rolling" and "ribbed" in Chinesephonetic alphabet, and 550 is the standard value of the tensile strength of thesteel bar (550MPa).

The code of the cold rolled surface steel bar isLG550 (L and G as "cold rolling" and "light surface" inChinese phonetic alphabet, and 550 is the standard value of the tensilestrength of the steel bar (550MPa).

Table a, mechanical properties of cold rolled steelbar

2.2 the diameter of the recommended steel is 5, 6,7, 8, 9, 10, and 12mm.

2.3 a single or double steel bar can be used in thelongitudinal reinforcement, and the horizontal bar should only use a singlesteel bar.

2.4 the dimensions of the vertical and horizontalbar of the same steel bar can be different, but the same size of the steel baris generally used in the same direction.

2.5 the diameter of the steel bar should be inaccordance with the requirements of the next type when the steel bars are bothhorizontal and horizontal.

Dmin = 0.6dmax

In the form: Dmax - the nominal diameter of thecoarser steel;

Dmin - the nominal diameter of the finer steel.

When double reinforcement is used in thelongitudinal reinforcement, the diameter of the steel bar should be inaccordance with the requirements of the next type.

0.7dt = DL = 1.25d

In the form: DT - the nominal diameter of thetransverse bar;

DL - the nominal diameter of one of the two rootsteel bars.

Size test

3.1 the length of longitudinal reinforcement ofsteel bar net is 50mm, and the spacing of transverse reinforcement should be25mm, and the minimum distance should be 100mm.

3.2 the extension length of the steel bar shouldnot be less than 25mm.

Surface quality test

There shall be no oil stains and other defects thataffect the use of the surface of the steel mesh, allowing burr, surface rustand local vacancy of the reinforced bar produced by sampling.

Quality (weight) test

The nominal weight of reinforcing steel net iscalculated according to the nominal diameter and the specified size of thereinforced bar. When calculating the density of the steel, the allowabledeviation between the actual quality and the nominal mass of the 0.00785g/mm.reinforcement net is 4.5%

Classification and marking

6.1 the steel mesh can be divided into two typesaccording to the shape of the fixed bar net and the custom reinforced bar net.

6.2, the spacing and diameter of reinforcing barsin two directions can be different, but in one direction they have the samediameter of reinforcement, the same reinforcement spacing and the samereinforcement length.

The 6.2.1 shaped steel mesh is represented by"longitudinal reinforcement spacing, transverse reinforcement spacing,longitudinal reinforcement strength grade, diameter * transverse reinforcementstrength grade and diameter mesh length * mesh width", for example:

100mm * 200mm - LL550100mm * LL550,8mm - 4800mm *2400mm

6.2.2 recommends a fixed steel mesh used in tableb.

Setting reinforced according to the verticalreinforcement spacing model of A, B, C three, and combined with thelongitudinal bars per meter area (mm/m) said. For example:

A 252 longitudinal bars per meter area of 252 mm/m,the longitudinal reinforcement spacing for A type steel mesh 200mm.

Table B, the recommended shaped steel mesh

6.3 the shape and size of the custom reinforced barnet should be determined by both parties and suppliers according to therequirements of the demand side, and are expressed in the design drawings.

Manufacture

7.1 the steel mesh should be mechanically manufactured,and resistance welding is adopted at the cross point of longitudinal andtransverse reinforcement.

7.2 the number of open welding at cross point ofsteel bar must not exceed 1% of the total number of cross points of the wholemesh. And the number of open welding points on any steel bar must not exceedhalf of the total number of cross points on the steel bar. No welding at thecrossing point on the steel bar.

Mechanical and technological properties

8.1 the mechanical and bending properties of thesteel mesh should be in accordance with the provisions of GB/T13788 for theLL550 cold-rolled ribbed steel bar and table a for the LG550 cold rolled steelbar.

8.2 the shear resistance of the steel mesh solder(unit N) should not be less than 150 and the product of the nominal crosssection of the coarser steel (unit mm).

Packing

9.1, the steel mesh should be strapped and firmly,and the weight should not exceed 2T. If necessary, rigid support or supportshould be added to prevent the deformation of the reinforcing steel mesh duringtransportation lifting.

application

1, the application of welded steel mesh in HighwayCement Concrete Pavement Engineering

The minimum diameter and maximum spacing of weldedsteel mesh for reinforced concrete pavement shall conform to the currentindustry standard "JTG D40" for highway cement concrete pavementdesign specification. When the cold-rolled ribbed reinforcement is used, thediameter of the steel bar should not be less than 8mm and the distance betweenthe longitudinal reinforcement should not be greater than 200mm, and thespacing of the transverse reinforcement should not be greater than that of300mm. The longitudinal and transverse reinforcement of welded network shouldbe of the same diameter. The thickness of the protective layer of thereinforcing bar should not be less than that of the 50mm. reinforced concretepavement. The welding network can be carried out according to the relevantprovisions of the welded network of the reinforced concrete pavement.

The concrete pavement and the fixed structure ofconvergence of the expansion joints cannot set the dowel bar, can be configuredin the adjacent structures in two-layer welded steel plate ends; or in therange of 6 to a length of about 10 times the thickness of the plate thicknesswill be gradually increased by 20%.

The concrete pavement and bridge connecting bridgeprovided by the board, should be set a long 6 10mm between the slab and theconcrete surface layer reinforced concrete layer transition plate. When the bridgeis oblique, the sharp angle part of the reinforced concrete slab should bestrengthened by the welded steel mesh.

The concrete surface layer under the box structurecross, the top surface to surface distance is less than 400mm or embedded inthe structure at the grassroots level, and both sides of the top width, theconcrete surface layer internal layout of two-layer welded steel mesh, weldedsteel mesh from the upper and lower surface layer top surface and the bottomsurface of a 1 /4 the 1/3 thickness.

Under the concrete surface, there is a circulartubular structure traversing. The distance from the top to the bottom of theconcrete surface is less than 1200mm. On the both sides of the structure, thesingle layer welded steel mesh should be laid in the concrete surface. Thewelded steel mesh is located at the thickness of 1/4 1/3 away from the top ofthe surface.

From the industry standard "highway cementconcrete pavement design code" JTG D40-2002

2, the application of welded steel mesh in BridgeEngineering

It is mainly applied to the bridge deck pavement ofmunicipal bridge and highway bridge, the old bridge surface renovation, thecrack prevention of the pier and so on. Through the quality inspection ofthousands of domestic bridge engineering application shows that the welding netincrease pavement quality, the protective layer thickness qualified rate above97%, improve the surface roughness of bridge deck pavement almost no cracks.The speed of more than 50%, lower deck pavement engineering price of about 10%.The welded steel mesh of bridge deck pavement should be welded by welding meshor prefabricated cold rolled ribs, so it is not suitable to use the weldedsteel mesh. The diameter and distance of the welded steel mesh used for bridgedeck pavement should be determined according to the structure of the bridge andthe load grade. The distance between the welded steel bars can be 100 one200mm, and the diameter of the welded steel bar should be 6 l00mm. The verticaland horizontal distance of welded steel mesh should be equally spaced, and thethickness of the protective layer of the welded net distance from the topsurface should not be less than 20mm.

3, the application of welded steel mesh in tunnellining

According to the national standard "highwaytunnel design code" JTGD70-2004 regulations.

In the design of sprayed concrete internal ribbedwelded steel fabric, is conducive to the improvement of sprayed concrete shearstrength and bending strength, improve the concrete anti punching ability, antibending ability, improve the integrity of sprayed concrete, reduce shrinkagecrack of sprayed concrete, prevent local drop. The mesh mesh of the weldedsteel bar should be arranged in a rectangle, and the distance between the steelbars of the welded bar net is 150 ~ 300mm. The combination of 150mm * 150mm,200mm x 200mm, 200mm * 250mm, 250mm x 300mm and 300mm x 300mm can be used. Thelength of the lap joint of the welded steel mesh should not be less than 30d (Dis the diameter of the steel bar).

The thickness of shotcrete protective layer forwelded steel mesh shall not be less than 20mm. When the double welded steelmesh is used, the spacing between the two layers of welded steel mesh shall notbe less than 60mm.

A survey of the development of welded steel mesh inChina

1 production capacity of welded steel mesh

The cold rolled ribbed bar began production at theend of 80s in China. It has been developing rapidly in recent 10 years,especially in recent years, and has become a new steel type popularized by theMinistry of construction. The rapid development of the cold-rolled ribbed steelbar provides good conditions for the development of the welding network. Thestandard of welding net products in China has been implemented in December1995, and it is of great significance to guide production and guarantee thequality of products. The use of regulations was formally implemented inFebruary 1998 and played a positive role in accelerating the promotion andapplication.

Technical regulations of 2 welded steel mesh

The technical regulations stipulate that thewelding network should be made of CRB550 - grade cold-rolled ribbed steel bar,and CRB510 - grade cold drawing steel bar can be used. The same type of steelis suitable for welding a welding net. The welding network is divided into twotypes according to shape and specification. The spacing and diameter of reinforcingbars in two directions can be different, but the steel bars in the samedirection should have the same diameter, spacing and length, which have beenstipulated in relevant standards and regulations. The shape and size of thecustomized welding network should be determined according to the design andconstruction requirements and the specific engineering conditions.

The diameter of the welded steel bar is 4-14mm, andthe diameter of 0.5mm can be used. Considering the transport conditions, thelength of the welding network should not exceed 12M, and the width should notexceed 3.4m. The distance between reinforcing bar and longitudinal bar shouldbe 100, 150 and 200mm, and the distance between reinforcing bars in the otherdirection is 100, 150, 200, 300mm, sometimes 400mm. When the verticalreinforced welded mesh for single steel bar, nominal diameter of thin steelshould not be less than the nominal diameter of the coarse steel 0.6 times,Dmin = 0.6damx. The shear resistance of welded joints (unit N) should not beless than 150 and the product of the nominal cross section (mm2) of the coarsereinforcement.