Reinforcement work

The steel bar for reinforced concrete refers to the straight bar or disc bar steel used for reinforced concrete reinforcement, and its shape is divided into two kinds of round steel bar and deformed steel bar, and the delivery status is straight bar and disc round two kinds。

The light round steel bar is actually a small round steel and disk circle of ordinary mild steel。变形钢筋是表面带肋的钢筋，通常带有2道纵肋和沿长度方向均匀分布的横肋。The shape of the transverse rib is spiral shape, herringbone shape and crescent shape。Expressed in millimeters of nominal diameter。The nominal diameter of a deformed bar is equivalent to that of a circular bar of equal cross-section。钢筋的公称直径为8-50毫米，推荐采用的直径为8、12、16、20、25、32、40毫米。钢种：20MnSi、20MnV、25MnSi、BS20MnSi。Steel bars are mainly subjected to tensile stress in concrete。变形钢筋由于肋的作用，和混凝土有较大的粘结能力，因而能更好地承受外力的作用。Steel reinforcement is widely used in various building structures。Especially large, heavy, light thin-walled and high-rise building structures。

 

分类

钢筋种类很多，通常按化学成分、生产工艺、轧制外形、供应形式、直径大小，以及在结构中的用途进行分类：

First, according to the size of the diameter

钢丝（直径3~5mm）、细钢筋（直径6~10mm）、粗钢筋（直径大于22m

钢筋

钢筋

m）。

Second, according to mechanical properties

Grade I steel (grade 235/420);Grade II steel (335/455);Grade III (400/540) and Grade IV (500/630)

Three, according to the production process

热轧、冷轧、冷拉的钢筋，还有以Ⅳ级钢筋经热处理而成的热处理钢筋，强度比前者更高。

(4) According to the role in the structure

Compression reinforcement, tension reinforcement, vertical reinforcement, distribution reinforcement, stirrup, etc

配置在钢筋混凝土结构中的钢筋，按其作用可分为下列几种:

1.Stress bars - steel bars that withstand tensile and compressive stress。

2.箍筋—承受一部分斜拉应力，并固定受力筋的位置，多用于梁和柱内。

3.Scaffolding - used to fix the position of the steel hoop inside the beam, forming the steel skeleton inside the beam。

4.Distribution rib - Used in the roof panel and floor, vertical arrangement with the stress reinforcement of the plate, the weight of the load is evenly transmitted to the stress reinforcement, and the position of the stress reinforcement is fixed, and the temperature deformation caused by thermal expansion and contraction is resisted。

5.Other - structural reinforcement for structural requirements or construction and installation。Such as waist reinforcement, embedded anchorage reinforcement, prestressed reinforcement, ring and so on。

 

According to the rolling shape

① Smooth steel bars: Grade I steel bars (Q300 steel bars) are rolled for smooth circular cross-section, the supply form is disk circle, the diameter is not more than 10mm, the length is 6m~12m。

② Ribbed steel: there are spiral, herringbone and crescent shape three, generally Ⅱ, Ⅲ grade steel rolled into adult shape, Ⅳ grade steel rolled into spiral and crescent shape。

③ Steel wire (divided into low carbon steel wire and carbon steel wire two kinds) and steel strand。

④ Cold rolled and twisted steel bars: cold rolled and cold twisted forming。

Diameter size:

钢丝（直径3~5mm）、细钢筋（直径6~10mm）、粗钢筋（直径大于22mm）。

 

Structure function:

Compression reinforcement, tension reinforcement, vertical reinforcement, distribution reinforcement, stirrup, etc

Rebar is now widely used in any building, for human progress has made better evidence, but also today's inspection of the quality of rebar members according to the minimum reinforcement rate of reinforcement, according to the principle of (equal area) replacement of rebar。

General reinforced concrete engineering commonly used steel bars:

（1）钢筋混凝土用钢第1部分：热轧光圆钢筋GB1499.1-2008

（2）钢筋混凝土用钢第2部分：热轧带肋钢筋GB1499.2-2007

(3) Steel for reinforced concrete - Part 3: steel welding mesh GB1499.3-2010

(4) Reinforced concrete waste heat treatment of steel GB13014-2013

(5) Low carbon steel hot rolled disc GB/T701-2008

(6) Cold rolled ribbed steel GB13788-2000

(7) Steel wire GB/T5223-2002 for prestressed concrete

(8) Low alloy steel wire YB/T038-93 for prestressed concrete

(9) Prestressed concrete steel strand GB/T5224-2003

(10) Steel strand for prestressed concrete ASTMA416-98A

(11) Cold rolled and twisted steel JG3046-1998

(12) Cold-drawn spiral bar DBJ14-BG3-96

 

Inspection of steel bars and technical inspection of steel joints:

钢筋的检验首先要检查钢筋的标牌号及质量证明书；其次要做外观检查，5% is taken from each batch of rebar ，Check the surface for cracks, wounds and lamination，The convex block on the steel bar surface shall not exceed the height of the transverse rib，The depth and height of the defect shall not be greater than the allowable and deviation of the location，The bending of the steel bar should not be greater than four meters per meter;Then mechanical properties test，If each batch is less than 60 tons, 2 sticks are drawn from it，Cut two pieces of each，Tensile and cold bending tests were performed respectively。在截取试件时应除去钢筋两端100－500MM，在截取试件大于60吨还需在取相应的钢筋。如果一项试验结果不符合要求，则从同一批中另取双倍数量的试样做各项试验。If there is still a sample unqualified, the batch of steel bars is unqualified, hot rolled steel bars in the process of brittle fracture, poor welding performance or significant abnormal mechanical properties and other phenomena, should be carried out chemical composition analysis and other special inspection。

成品

Waste heat treatment of steel bars: immediately after hot rolling through water, surface control cooling, and then use the core waste heat itself to complete the finished steel bars obtained by tempering treatment。

带肋钢筋：表面通常带有两条纵肋和沿长度方向均匀分布的横肋的钢筋。

Crescent rib bar: bar whose longitudinal section of the transverse rib is crescent shaped and does not intersect the longitudinal rib。

Longitudinal ribs: uniformly continuous ribs parallel to the axis of the steel bar。

Transverse rib: Other rib not parallel to longitudinal rib。

带肋钢筋的公称直径：与钢筋的公称横截面积相等的圆的直径。

带肋钢筋的相对肋面积：横肋在与钢筋轴线垂直平面上的投影面积与钢筋公称周长和横肋间距的乘积之比。

绑扎

Thread connection and binding are still one of the main means of steel bar connection。 When the rebar is tied，Intersections of rebar are fastened with iron wire;Mesh of steel for boards and walls，Except for the intersection of the two lines of the outer steel bar are all fastened，The intersections of the middle part can be separated by staggered ties，保证受力钢筋位置不产生偏移；梁和柱的箍筋应与受力钢筋垂直设置，The overlap of the curved hook should be staggered along the direction of the stressed steel bar。受拉钢筋和受压钢筋接头的搭接长度及接头位置符合施工及验收规范的规定。

The binding of steel bars shall comply with the following provisions:

1.The joints of the rebar shall be fastened with iron wire;

2.板和墙的钢筋网片，另须在中间部分的相交点可相间隔交错的扎牢，但要保证受力钢筋不发生位移。Two-way force steel mesh, must be tied firmly;

3.The reinforcement of beams and columns, except as required by design, shall be arranged vertically to the bearing reinforcement。

4.板、次梁与主梁交叉处、板的钢筋在上，次梁钢筋居中，主梁的钢筋在下；当有圈梁或垫梁时，主梁的钢筋在上。

Allowable deviation

The surface of the steel bar shall not be cracked, scarred or folded。The surface of the steel bar is allowed to have a convex block, but it must not exceed the height of the transverse rib, and the depth and height of other defects on the surface of the steel bar must not be greater than the allowable deviation of the size of the location。

Dimensions, shape, weight and permissible deviations:

1) Nominal diameter range and recommended diameter

The nominal diameter of the steel bar ranges from 6 to 25mm, and the standard recommended nominal diameter of the steel bar is 6, 8, 10, 12, 16, 20, 25, 32, 40, 50mm。

2) Allowable deviation of surface shape and size of ribbed steel plate

Ribbed steel rib should meet the following basic requirements:

横肋与钢盘轴线的夹角β不应小于45度，当该夹角不大于70度时，钢筋相对两面上横肋的方向应相反；

Transverse ribs and spacing l shall not be greater than 0 of the nominal diameter of the steel bar.7倍；

The Angle α between the transverse rib side and the reinforcement surface shall not be less than 45 degrees;

钢筋相对两面上横肋末端之间的间隙（包括纵肋宽度）总和不应大于钢筋公称周长的20%；

When the nominal diameter of the steel bar is not greater than 12mm, the relative rib area should not be less than 0.055；公称直径为14mm和16mm，相对肋面积不应小于0.060;When the nominal diameter is greater than 16mm, the relative rib area should not be less than 0.065。

3) Length and allowable deviation

a, length: the steel bar is usually delivered according to the fixed length, the specific delivery length should be indicated in the contract; When rebar is delivered in reels, each rebar shall be one rebar and 5% of  reels (or two if less than two reels) of each lot shall be allowed to consist of two rebars。The disk weight and diameter shall be determined by negotiation between the supply and demand parties。

b、长度Allowable deviation：钢筋按定尺交货时的长度Allowable deviation不得大于+50mm。

c、弯曲度和端部：直条钢筋的弯曲变应不影响正常使用，总弯曲度不大于钢筋总长度的0.4%;The end of the steel bar should be cut straight, and the local deformation should not affect the use。

加工

钢筋加工一般要经过四道工序：钢筋除锈；钢筋调直；钢筋切断；钢筋成型。

当钢筋接头采用直螺纹或圆锥螺纹连接时，还要增加钢筋端头镦粗和螺纹加工工序。Rebar batching and replacement Rebar replacement

（1）以另一种钢号或直径的钢筋代替设计文件中规定的钢筋时，应遵守以下规定：

It should be carried out according to the principle that the design value of the bearing capacity of the steel bar is equal, and the structural requirements such as the spacing of the steel bar, the anchoring length and the minimum diameter of the steel bar should be met after the replacement。

以高一级钢筋代换低一级钢筋时，宜采用改变钢筋直径的方法而不宜采用改变钢筋根数的方法来减少钢筋截面积。

(2) When a steel bar of the same diameter is used to replace a steel bar of another diameter, the diameter change range should not exceed 4mm, and the ratio of the total section area of the steel bar after the change to the section area specified in the design document should not be less than 98% or more than 103%。

(3) When the design main reinforcement is replaced with the same steel number, the spacing should be kept unchanged, and two types of reinforcement spacing configurations with diameters larger and smaller than the diameter of the design reinforcement can be replaced。

Cold-rolled steel bar

Since the late 1980s, our country began to introduce the cold-rolled ribbed steel bar production equipment。先后有南京、苏州、上海、青岛、沧州、昆明等地分别从德国、意大利等国引进11套设备。九十年代中期又有安徽、广东、江苏等省的合资或外商独资企业，从国外引进几条生产线。At the same time。Some domestic scientific research institutions and enterprises to develop or imitation cold rolling equipment。迄今已有十多个单位在生产和销售Cold-rolled steel bar全套设备，分布于北京、辽宁、江苏、河北、天津等地。还有一些设备生产企业，在几年来激烈的市场竞争中，由于产品性能不良或质量低劣被淘汰。

迄今国内已建冷轧带肋钢筋生产线约有400多条，年生产能力200万吨，分布在26个省、市。

从所了解的各省情况看，在建设部和各省市建委的大力推动下，冷轧带肋钢筋的推广工作有了很大进展。Some provinces have made outstanding achievements, among which Jiangsu and Liaoning provinces have the largest promotion surface, and cold-drawn low carbon steel wire has been eliminated in prefabricated components;In situ concrete structure also has a large number of applications, Sichuan, Fujian Province in this area of the promotion work is very successful。此外，北京、河北、湖南、安徽、山西、山东、广东、浙江、上海等省市也陆继开始推广应用。According to incomplete statistics。In 1998 alone, the national promotion volume has exceeded 600,000 tons。The building area for urban and rural housing and public construction is 1.500 million square meters, there will be greater growth in the future。

In terms of production and application technology，Our country has developed based on the introduction，For example, the tensile strength of cold-rolled ribbed steel has been developed from one strength level abroad to three levels: CRB550, CRB650 and CRB800;The application range is also expanded from non-prestressed concrete structural members abroad to prestressed concrete members。为推广应用钢筋，国家和一些省市主管部门组织编制了有关标准和图集。国家标准《IM体育平台|IM体育官方网站》GB13788─2008已经实施。行业标准《IM体育》JGJ95─2011已于2012年4月1日起施。

The State Science and Technology Commission has included steel bars in the national key promotion projects。The Ministry of Construction included it as one of the 10 new technologies focused on promotion in the construction industry during the "Ninth Five-Year Plan" and "Tenth Five-Year Plan" period (included in the "high-efficiency steel bar and prestressed concrete technology" project)。

 

 

要求

钢筋加工制作时，要将钢筋加工表与设计图复核，检查下料表是否有错误和遗漏，对每种钢筋要按下

Check whether the material table meets the requirements, after these two checks, and then release the real sample according to the material table, the trial production can be made in batches, and the processed steel bars should be stacked neatly and orderly。

If the replacement of steel bars is required in construction, it is necessary to fully understand the design intent and the performance of the replacement material, strictly comply with the various provisions of the current reinforced concrete design code, and it is not possible to replace low-strength steel bars with high-strength steel bars of equal area。凡重要部位的钢筋代换，须征得甲方、设计单位同意，并有书面通知时方可代换。

（1）钢筋表面应洁净，粘着的油污、泥土、浮锈使用前必须清理干净，可结合冷拉工艺除锈。

(2) Steel bar straightening, can be mechanically or manually straightened。经调直后的钢筋不得有局部弯曲、死弯、小波浪形，其表面伤痕不应使钢筋截面减小5%。

(3) The steel bar should be cut according to the steel bar number, diameter, length and quantity, the length of the match, the first cut the long material after the short material, as far as possible to reduce and shorten the short head of the steel bar, in order to save steel。

(4) Bar bending or bending:

① Steel bar bend hook。There are three kinds of forms, which are semicircular curved hook, straight curved hook and oblique curved hook。After the bending of the steel bar, the inner wall of the bending area shrinks, the outer skin extends, the axis length remains unchanged, and the bending area forms an arc. The bending size is larger than the cutting size, and the bending adjustment value should be considered。The bending center diameter of the bar is 2.5d, the flat part is 3d。The theoretical calculation value of increasing the length of the bar bend: the semicircular bend is 6.5d, the straight hook is 3.5d, the diagonal hook is 4.9d。

② Bend the bar。The bending diameter D at the bend of the middle part is not less than 5 times the diameter of the steel bar。

③ stirrup。The end of the stirrup should be bent, and the form of the bent hook should meet the design requirements。箍筋调整，即为弯钩增加长度和弯曲调整值两项之差或和，根据箍筋量外包尺寸或内包尺寸而定。

④钢筋下料长度应根据构件尺寸、混凝土保护层厚度，钢筋弯曲调整值和弯钩增加长度等规定综合考虑。 

a. Cutting length of straight steel bar = length of member - thickness of protective layer + bending hook to increase length,

b. 弯起钢筋下料长度=直段长度+斜弯长度-弯曲调整值+弯钩增加长度，

c. Stirrup cutting length = stirrup inner circumference + stirrup adjustment + hook length increase。

Installation requirements

钢筋绑扎前先认真熟悉图纸，检查配料表与图纸、设计是否有出入，仔细检查成品尺寸、心头是否与

The cut sheet matches。Perform binding only after the verification is correct。采用20#铁丝绑扎直径12以上钢筋，22#铁丝绑扎直径10以下钢筋。

 

墙

① The steel mesh of the wall is tied to the same foundation。When the steel bar has a 90° bend hook, the bend hook should face into the concrete。

②采用双层钢筋网时，在两层钢筋之间，应设置撑铁（钩）以固定钢筋的间距。

(3) When the wall reinforcement is tied, the vertical degree should be controlled by the hanging line, and the distance between the main reinforcement should be strictly controlled。The three levels on both sides of the shear wall should be fully tied, and the rest can be tied with plum points。

(4) In order to ensure the correct position of the rebar, tie a horizontal reinforcement or stirrup outside the vertical reinforcement, and spot weld it with the vertical reinforcement to fix the position of the wall and column reinforcement, and correct it with a line hammer when spot welding is fixed。

⑤外墙浇筑后严禁开洞，所有洞口预埋件及埋管均应预留，洞边加筋详见施工图。The rebar reserved in the wall and column should be welded into a path for lightning protection grounding leads。Its location, quantity and practice are detailed in the installation and construction drawings. Qualified welders should be selected to carry out welding work, and the structural reinforcement should not be damaged. The pre-burial of hydropower installation must be coordinated with civil construction, and the wrong burial and leakage burial should not be allowed。

Beam and plate

(1) When the longitudinal loaded steel bars are arranged in double or multiple layers, a short steel bar with a diameter of 15mm should be placed between the two rows of steel bars. If the diameter of the longitudinal steel bar is greater than 25mm, the diameter specification of the short steel bar is the same as that of the longitudinal steel bar。

②箍筋的接头应交错设置，并与两根架立筋绑扎，悬臂挑梁则箍筋接头在下，其余做法与柱相同。The outer corner of the main beam and the stirrup should be fully tied, and the rest can be tied at the plum point。

③ The binding of the steel mesh of the plate is the same as that of the foundation, and the crossing points of the steel bars of the two-way plate should be fully tied。It should be noted that the negative steel bar (face reinforcement) on the upper part of the board should be prevented from being stepped on;In particular, awning, overhanging eaves, balconies and other cantilever plates should strictly control the position and height of the negative reinforcement。

④ At the intersection of the plate, the secondary beam and the main beam, the steel bar of the plate is on the top, the steel bar of the secondary beam is in the middle layer, and the steel bar of the main beam is on the bottom, when there is a ring beam or a cushion beam, the main beam is on the top。

⑤ The bending starting point of the floor steel bar, such as the processing plant (field) in the processing of no bending, the design drawings and no special note, can bend the steel bar according to the following provisions, the side span support of the plate according to the span 1/10L as the bending starting point。The middle span of the plate and continuous multiple spans can be bent by 1/6L of the center line of the support。

⑥框架梁节点处钢筋穿插十分稠密时，应注意梁顶面主筋间的净间距要有留有30mm，以利灌筑混凝土之需要。

⑦ The binding joint of the steel bar shall meet the following requirements:

1）搭接长度的末端距钢筋弯折处，不得小于钢筋直径的10倍，接头不宜位于构件最大弯矩处。

2）受拉区域内，Ⅰ级钢筋绑扎接头的末端应做弯钩，Ⅱ级钢筋可不做弯钩。

3) The joint of the steel bar should be fastened with wire at the center and both ends。 

4) The lap length of the binding joint of the tensile steel bar should meet the requirements of the structural design。

5) The thickness of the concrete protective layer of the stressed steel bar should meet the requirements of the structural design。

6）板筋绑扎前须先按设计图要求间距弹线，按线绑扎，控制质量。

7）为了保证钢筋位置的正确，根据设计要求，板筋采用钢筋马凳纵横@600予以支撑。

Reinforcement lengthening

根据设计要求，本工程直径≥18的钢筋优先采用机械接长，套筒挤压连接技术，其余Reinforcement lengthening，水平筋

Welding requirement

Steel bar welding is divided into two forms: pressure welding and fusion welding。压焊包括Flash butt welding、Resistance spot welding和Gas pressure welding；熔焊包括Arc welding和Electroslag pressure welding。In addition, the welding of the steel bar and the T-shaped joint of the embedded part should use submerged arc pressure welding, arc welding or perforated plug welding, but the welding current should not be large to prevent the burn of the steel bar。

Flash butt welding

Flash butt welding is widely used for steel bar connection and welding of prestressed steel bar and screw end bar。Priority should be given to flash butt welding of hot rolled steel bars。Flash butt welding of steel bar (is the use of butt welding machine to make two sections of steel bar contact, through a low voltage strong current, after the steel bar is heated to a certain temperature and becomes soft, the axial pressure top forging is carried out to form a butt welding joint。钢筋Flash butt welding工艺常用的有连续闪光焊、预热闪光焊和闪光—预热—闪光焊。The Ⅳ grade steel bar is sometimes subjected to electric heat treatment after welding。

Arc welding

Arc welding is the use of arc welding machine to produce high temperature between the welding rod and the welding parts, arc melting of the welding rod and the welding parts within the arc burning range, to be solidified to form a weld or joint, arc welding is widely used in steel bar joints, steel bar skeleton welding, prefabricated structural joint welding, steel bar and steel plate welding and various steel structure welding。The joint forms of steel bar arc welding are: lap welding head (single side weld or double side weld), side welding head (single side weld or double side weld), split welding head (flat welding or vertical welding) and groove side welding head。

Weld joint quality inspection in addition to appearance, also need to sample for tensile test。如对焊接质量有怀疑或发现异常情况，还可进行非破损检验（X射线、γ射线、超声波探伤等）。

Electroslag pressure welding

Electroslag pressure welding在施工中多用于现浇混凝土结构构件内竖向或斜向（倾斜度在4:1的范围内）钢筋的焊接接长。Electroslag pressure welding has two kinds: automatic and manual electroslag pressure welding。与Arc welding比较，它工效高、成本低，可进行竖向连接，故在工程中应用较普遍。Suitable welding transformer should be used for electroslag pressure welding。夹具需灵巧，上下钳口同心，保证上下钢筋的轴线最大偏移不得大于0.1d, and no larger than 2mm。

When welding, first remove the rust within about 120mm of the end of the steel bar, clamp the clamp on the lower steel bar, and straighten the upper steel bar in the moving electrode。In the process of automatic electroslag pressure welding, wire rings for starting arc are also placed between the upper and lower steel bars。再装上药盒，装满焊药，接通电路，用手柄使电弧引燃（引弧）。然后稳定一定时间，使之形成渣池并使钢筋熔化（稳弧），随着钢筋的熔化，用手柄使上部钢筋缓缓下送。当稳弧达到规定时间后，在断电同时用手柄进行加压顶锻（顶锻），以排除夹渣和气泡，形成接头。待冷却一定时间后，即拆除药盒、回收焊药、拆除夹具和清除焊渣。The three processes of arc starting, arc stabilizing and top forging are carried out continuously。

Resistance spot welding

Resistance spot welding主要用于小直径钢筋的交叉连接，如用来焊接推广应用的钢筋网片、钢筋骨架等。It has high production efficiency, material saving and wide application。The working principle of resistance spot welding is that when the steel bar is cross-spot welding, the contact point is only one point, and the contact resistance is large, at the moment of contact, all the heat generated by the current is concentrated on one point, so that the metal is heated and melted, and the welding spot metal is welded under the electrode pressure。

When resistance spot welding steel bars of different diameters, such as the diameter of smaller steel bars is less than 10mm, the diameter ratio of large and small steel bars should not be greater than 3;If the diameter of the smaller steel bar is 12mm or 14mm, the ratio of the diameter of the size of the steel bar should not be greater than 2。The welding process parameters should be selected according to the steel bar with smaller diameter。

Solder joints should be inspected and tested for appearance and strength。Hot-rolled rebar。Solder joints should be subjected to shear tests。In addition to shear test, tensile test should also be carried out for solder joints of cold working steel bars。

Gas pressure welding

Gas pressure welding steel bar is the use of acetylene - oxygen mixed gas combustion of high temperature flame to heat the initial pressure of the two steel bar end joint, so that the end of the steel bar plastic deformation, and promote the metal atoms of the steel bar end to spread each other, when the steel bar is heated to about 1250~1350℃ (equivalent to the melting point of steel 0.80~0.90 times) when pressurized overhead forging is performed to weld the rebar together。

Gas pressure welding of steel bar belongs to hot pressure welding。In the welding heating process, the heating temperature is only 0 of the melting point of the steel.8~0.9 times, and the heating time is short, so there is no tendency of steel bar material deterioration。另外，它设备轻巧、使用灵活、效率高、节省电能、焊接成本低，可进行全方位（竖向、水平和斜向）焊接。So it was gradually promoted in our country。

The heating energy in the heating system is oxygen and acetylene。用流量计来控制氧和乙炔的输入量，焊接不同直径的钢筋要求不同的流量。After the heater is used to mix oxygen and acetylene, the flame is emitted from the nozzle to heat the steel bar, and the flame is required to heat the steel bar evenly, have sufficient temperature and power, and be safe and reliable。

The pressure source in the pressurizing system is the electric oil pump, which makes the pressure of the pressurizing forging stable。The crimper is one of the main equipment of gas pressure welding, which is required to accurately and conveniently fix two steel bars on the same axis, and evenly transfer the pressure generated by the oil pump to the steel bar for welding purposes。

Gas pressure welding接的钢筋要用砂轮切割机断料，要求端面与钢筋轴线垂直。焊接前应打磨钢筋端面，清除氧化层和污物，使之现出金属光泽，并即喷涂一薄层焊接活化剂保护端面不再氧化。

 

性能

 

Steel bar process performance includes many items, according to the characteristics of different products can be put forward different requirements, such as ordinary steel bar requirements for bending and reverse bending (reverse bending) test, some prestressed steel is required to carry out repeated bending, torsion, winding test。

所有这些试验的形式不同程度地模拟了材料在实际使用时可能涉及的工艺加工方式，For example, ordinary steel bars need to be bent or bent，Prestressed steel wire sometimes needs to be wound，The purpose is to test the ultimate bearing capacity of the material to these specific plastic deformation，Therefore, the process performance is also a plastic requirement for the material，And with the above ductility (elongation) requirements are connected，Generally speaking, steel with high elongation，The process performance is good。

However, compared with the unidirectional stress state during stretching，The stress state of process performance test is much more complicated，The deformation type and size of the sample are different in all directions (axial and radial)，The microstructure, grain size, harmful residual element content of the steel, especially any internal and surface defects that affect continuous deformation such as cracks, inclusions, etc., may affect and cause the test to fail。所以在某种意义上，对于考核钢材的质量，可以说Process performance试验更为严格。

In addition, the reverse bending test of steel bars is essentially a strain aging sensitivity test. This is because the molten steel generally contains a certain amount of free nitrogen (N), also known as residual nitrogen. When the content is too high, the steel can be embrittlement at room temperature after plastic deformation。

Since steel bars often need to be bent and formed after use，A plastic deformation has been created，If the wood becomes brittle，The structure will not be able to withstand the external load (such as an earthquake) that causes plastic deformation of the steel bar.，Therefore, the reverse bending test is included in the steel bar standard as an important technical requirement at home and abroad，At the same time, the nitrogen content of steel is limited (no more than 0.012%）。

Research shows that，Some elements used in the microalloying of steel such as vanadium, titanium, niobium, etc，In particular, vanadium has a good affinity with nitrogen，The addition of vanadium to steel can effectively bind free nitrogen，The combination of vanadium and nitrogen can further enhance the strengthening effect of vanadium on steel，因此有些标准也注明“如果有足够的与氮结合的元素存在氮含量可以高出标准规定”。

Since the anchoring agent is made of high-strength material as aggregate, gelled material as binder, supplemented by high-flow micro-expansion anti-segregation and other substances, its composition is mainly inorganic materials, organic materials as auxiliary, no corrosion effect on steel bars。Therefore, a certain anchorage force can be generated within a few hours。具有快凝、快硬、高强、无收缩、剪切强度高、贯入阻力小等特点。本工法适用于所有矿山巷道、隧道、水利、边坡支护等工程3m以内围岩层锚杆的支护。

Mechanical property

钢筋的Mechanical property通过试验来测定，测量钢筋质量标准的Mechanical property有屈服点、抗拉强度、elongation，Cold bending property等指标。

Yield point (fy)

When the stress of the steel bar exceeds the yield point, the tension does not increase but the deformation increases significantly, which will produce a large residual deformation, the tension value of the steel bar unit area borne by the tension value divided by the cross-sectional area of the steel bar is the yield point σs°

Tensile strength (fu)

抗拉强度就是以钢筋被拉断前所能承担的最大拉力值除以钢筋截面积所得的拉力值，抗拉强度又称为极限强度。It is the largest stress value in the stress-strain curve, although it has no direct significance in the strength calculation, but it is an essential guarantee item in the mechanical properties of the steel bar。因为：

(1) Tensile strength is the ultimate capacity of the steel bar to withstand static load, which can represent how much strength reserve the steel bar has after reaching the yield point, and is an important indicator of resistance to plastic damage。

(2) The steel bar has defects in the melting and rolling process, as well as the instability of the chemical composition of the steel bar, often reflected in the tensile strength, when the carbon content is too high, the temperature at the end of the rolling is too low, the tensile strength may be high;When the carbon content is small and the non-metallic inclusions in the steel are too much, the tensile strength is low。

（3）抗拉强度的高低，对钢筋混凝土结构抵抗反复荷载的能力有直接影响。

elongation

Elongation is the maximum strain value when the specimen is broken in the stress-strain curve, also known as elongation, which is an indicator to measure the plasticity of the steel bar, and the same as the tensile strength, is also an essential guarantee item in the mechanical properties of the steel bar。

elongation的计算，是钢筋在拉力作用下断裂时，被拉长的那部分长度占原长的百分比。When the two sections of the specimen are broken together, the length of the standard distance section L1 after fracture can be measured, and the plastic deformation value can be obtained by subtracting the original length L0 of the standard distance. The ratio between this value and the original length is expressed by δ, that is, the larger the δ value of the elongation, the better the plasticity of the steel。elongation与标距有关，对Hot-rolled rebar标距取试件直径的10倍长度作为测量的标准，其elongation以δ10表示。对于钢丝取标距长度为100mm作为测最检验的标准，以δ100表示。For steel strand, it is δ200。

Cold bending property

Cold bending property是指钢筋在经冷加工（即常温下加工）产生塑性变形时，对产生裂缝的抵抗能力。Cold bending test is a test to determine the ability of steel bars to withstand bending deformation at normal temperature。The size of the stress should not be considered in the test, and the steel bar specimen with diameter d is bent to 180° or 90° around the bending center of diameter D (D specifies 1d, 3d, 4d, 5d)。Then check the steel bar sample for cracks, scale, fracture and other phenomena to identify whether its quality meets the requirements, cold bending test is a more stringent inspection, can reveal the internal organization of the steel bar uneven defects。

Mechanical property

1）钢筋的Mechanical property应符合下表规定：牌号Nominal diameter mmσs

牌号

Nominal diameter mm

Sigma s(or sigma p0).2)

Mpa

σb

MPa

δ5

%

HRB335

6-25

28-50

335

490

16

HRB400

6-25

28-50

400

570

14

HRB500

6-25

28-50

500

630

12

2) The total elongation of the steel bar at the maximum force δgt is not less than 2.5%。Inspection is not required if the supplier can guarantee it。

3) According to the requirements of the demander, the steel bar can be supplied to meet the following conditions:

a) The ratio of the measured tensile strength of the steel bar to the measured yield point is not less than 1.25；

b) The ratio between the measured yield point of the steel bar and the minimum yield point specified in the table above shall not be greater than 1.30。

Process performance

1) Bending performance

按下表规定的弯心直径弯曲180度后，钢筋受弯曲部位表面不得产生裂纹。Grade nominal diameter a

2) Reverse bending performance

According to the requirements of the customer, the steel bar can be tested for reverse bending performance。

The diameter of the bending center in the reverse bending test is correspondingly increased by one bar diameter。First forward bending 45 degrees, then reverse bending 23 degrees, then reverse bending 23 degrees。After the reverse bending test, the surface of the bending part of the steel bar should not crack。

 

重量

The unit of measurement for theoretical weight calculation of steel is kg (kg)。The basic formula is:

W（重量，kg）=F（断面积m2）×L（长度，m）×ρ（密度，g/cm3）×1/1000

The density of steel is: 7.85g/cm3, rebar theoretical weight calculation formula is as follows:

W=0.00617 x d2 (kg/m)

d=断面直径mm，如断面直径为12mm的螺纹钢，每米重量=0.00617×144=0.888kg

工程

Engineering quantity calculation rules

1、钢筋工程，应区别现浇、预制构件、不同钢种和规格，分别按设计长度乘以单位重量，以吨计算。

2, when calculating the amount of steel reinforcement, the design has specified the length of the steel tower, according to the specified length of the tower;If the tower connection length is not specified in the design, it has been included in the loss rate of steel bars, and the tower connection length is not calculated separately。Steel bar electroslag pressure welding, sleeve extrusion and other joints, to a calculation。

3, the pre-tensioned prestressed steel bar, according to the dimensions of the component to calculate the length, the post-tensioned prestressed steel bar according to the design of the prestressed steel reserved hole length, and distinguish different anchorage types, respectively, according to the following provisions:

（1)低合金钢筋两端采用螺杆锚具时，预应力的钢筋按预留孔道长度减0.35m, screw separately calculated。

（2）低合金钢筋一端采用徽头插片，另一端螺杆锚具时，预应力钢筋长度按预留孔道长度计算，螺杆另行计算。

（3）低合金钢筋一端采用徽头插片，另一端采用帮条锚具时，预应力钢筋增加0.15m, the prestressed steel bar is increased by 0 when the anchor is used at both ends.3m computing。

（4）低合金钢筋采用后张硅自锚时，预应力钢筋长度增加0.35m computing。

(5) When JM,XM,QM type anchorage channel length is less than 20m, the length of prestressed steel bar is increased by lm;When the length of the channel is more than 20m, the length of the prestressed steel bar is increased by 1.8m computing。

(6) The carbon steel wire is tapered anchor, and the length of the prestressed steel bar is increased by lm when the channel length is within 20m;When the channel length is more than 20m, the length of the prestressed steel bar is increased by 1.8m.

(7) When the carbon steel wire is upset at both ends, the length of the prestressed steel wire is increased by 0.35m computing。

Determination of length

1, the thickness of concrete protective layer of reinforcement

The thickness of the concrete protective layer of the stressed steel bar should meet the design requirements, and when the design has no specific requirements, it should not be less than the diameter of the stressed steel bar, and should meet the requirements of the following table:

（1）轻骨料砼的钢筋的保护层厚度应符合国家现行标准《IM体育》。

(2) Prefabricated components produced by factories in normal indoor environments，When the concrete strength grade is not lower than C20 and the construction quality is reliably guaranteed，The thickness of the protective layer can be reduced by 5mm as specified in the table，但预制构件中的预应力钢筋的保护层厚度不应小于15mm；处于露天或室内高湿度环境的预制构件，When the surface is coated with cement mortar and there are reliable quality assurance measures, the protective layer thickness can be used according to the protective layer thickness value of the component in the normal indoor environment in the table。

(3) reinforced concrete flexural members, the thickness of the protective layer of the reinforcement end is generally 10mm;The thickness of the protective layer of the main rib of the prefabricated ribbed plate can be considered according to the beam。

(4) The thickness of the protective layer of steel bars distributed in the plate, wall and shell should not be less than 10mm;The protective layer thickness of stirrup and structural reinforcement in beams and columns should not be less than 15mm。

2, the length of the curved hook of the steel bar

Ⅰ级钢筋末端需要做1800、1350、900、弯钩时，其圆弧弯曲直径D不应小于钢筋直径d的2.5 times, the length of the straight part should not be less than 3 times the diameter of the steel bar d;The inner diameter of HRRB335 and HRB400 steel bars should not be less than 4 times the diameter of the steel bar d, and the length of the straight part of the bend hook should meet the design requirements。

3, bend the steel bar to increase the length

The bending Angle of the steel bar is generally 300, 450, 600 three kinds, and the bending added value refers to the difference between the diagonal length of the steel bar and the horizontal projection length。

4. Length of stirrup

The end of the stirrup should be bent, and the form of the bent hook should meet the design requirements。When the design does not have specific requirements, the stirrup made of grade I steel or low carbon steel wire, the bending diameter of the bending hook D should not be greater than the diameter of the stressed steel bar, and not less than 2 of the diameter of the stirrup.5 times;The length of the straight part of the hook, of the general structure, should not be less than 5 times the diameter of the stirrup;The length of the straight part of the stirrup hook of the structural member with seismic requirements should not be less than 10 times the diameter of the stirrup。

Anchorage length of steel bar

Anchorage length of steel bar，是指各种构件相互交接处彼此的钢筋应互相锚固的长度。If the design drawing clearly stipulates, the anchorage length of the steel bar shall be calculated according to the drawing;When the design has no specific requirements, it is calculated according to the provisions of the "Code for the Design of Concrete Structures"。

GB50010—2002规范规定：（1）受拉Anchorage length of steel bar（2）圈梁、构造柱钢筋锚固长度

Other questions

When calculating the amount of reinforcement, it is also necessary to pay attention to the reinforcement not drawn and not clearly indicated in the design drawings, such as the additional distribution bars of the upper negative bending moment of the double reinforcement bars in the floor, the horse stool used to support the double reinforcement of the base plate in the construction of the reinforced concrete wall and the tension bars used in the construction。These should be calculated according to the requirements of the code and incorporated into its steel dosage。

 

Tensile test

Main use

LAW系列微机控制电液伺服卧式Tensile test机采用机架整体钢板焊接框架结构，Single rod double acting piston cylinder applied test force，Cylindrical pin insert sample，Load sensors measure force，The drawing space can be adjusted according to the sample specification length，Computer screen controls and displays test force and test curve，Automatically process test data according to the requirements of test method，本机为吊装带类、链类以及绳索类做产品逐个拉伸试验专用设备,Used for lifting belt products one by one tensile load,Failure test,It requires flexible and convenient operation,Slow and smooth loading,The body has the advantages of strong carrying capacity。

Performance characteristics

1 主机：

1.1机架整体采用钢板焊接框架结构，通过前后夹头座、油缸及前横梁组成系统主结构；

1.2. The rear chuck seat is manually pushed to adjust the test space.

1.3 The shape of the main machine is designed on the basis of meeting the technical requirements of the horizontal test equipment. The shape is simple and bright, the proportion is coordinated, and the color is reasonable, so that the stability, safety and beauty of the test equipment are unified。

2 Oil source system (pumping station) :

2.1 一套10l/min,30MPa恒压泵组：采用国内知名品牌电机，进口低噪声高压齿轮泵。

2.2 电机安装配有减振装置（选用减振垫），以减小振动和噪音；

2.3 Oil tank: fully enclosed standard oil tank, volume 80 liters, equipped with oil temperature gauge, oil level gauge, precision pressure filter, air filter, etc., and with oil temperature, liquid level, oil resistance protection and indication device, according to the use of the oil circuit with the corresponding high-precision oil filter device。

2.4 具有温度过限、滤油器堵塞、液位过低等自动停机或报警功能；

2.5 管路系统：主油缸加载器、夹头作动器的液压管路采用高压软管连接。

3 Control system:

3.1 双通道控制板全部采用数字化电路，结构一致，提高了各通道的互换性；

3.2 计算机屏幕完成集成的数据控制显示与试验曲线显示功能；

3.3 Perfect data storage function, historical data can be reproduced and graphical display;

Product model	LAW-500	LAW-1000	LAW-2000
Maximum test force (kN)	500	1000	2000
Test force measurement range	10KN-500kN	20KN-1000kN	40KN-2000kN
Test the accuracy of force indication	±1%
Displacement measurement resolution	0.01mm
Test speed	0-80mm/min
Pull head no-load fast forward speed	Not less than 200mm/min
Test space (excluding piston stroke)	500-6000mm(graded adjustment 500mm first gear)
Piston stroke	1100mm
Working center height	350mm
Main engine dimensions	9000x1200x500mm