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【工程施工类翻译】钢筋
发布时间:2011-7-14 22:01:00||  点击:3966次||  文章分类:翻译案例||  发布人:翻译家(Fanyijia.com)


钢 筋

 

一、 范围

本节工作内容包括桥梁及结构物工程中钢筋的供应、试验、储存、加工及安装。

二、 材料

1. 一般要求

(1)带肋钢筋应符合《钢筋混凝土用热轧带肋钢筋》(GB 1499-1998)的规定,光圆钢筋应符合《钢筋混凝土用热轧光圆钢筋》(GB 13013-1991)的规定。钢筋的主要力学、工艺性能见表-1。

                    钢筋的主要力学、工艺性能          表-1

钢筋类型及牌号

R235

HRB335

HRB400

直径(mm)

6~20

8~25

28~50

8~25

28~50

最小屈服强度(MPa)

235

335

400

最小抗拉强度(MPa)

370

490

570

钢筋类型及牌号

R235

HRB335

HRB400

延伸率δ5 (%)

25

16

14

180°冷弯内径

2.5d

3d

4d

4d

5d

注:“d”为钢筋公称直径。

(2)国际上采用的符合标准的其它钢筋,如监理工程师批准,也可采用。

(3)钢筋笼或钢筋骨架中的钢板及其他项目所用的结构钢材,应符合图纸要求及《碳素结构钢》(GB 700—1988)的Q235钢的性能,结构钢材应和钢筋一样进行检验。

2. 检验证明

除监理工程师另有许可外,承包人应向监理工程师提供拟用于工程的每批钢筋的一式三份工厂试验报告。工厂试验报告应由具有法律资格且能制约制造商的保证人(如政府质量监督部门)签字,且提供以下资料:

(1)轧制钢筋的生产方法;

(2)每炉或每批钢筋的鉴定(包括拉力试验,弯曲试验结果);

(3)每炉或每批钢筋的物理化学性能。

3. 识别标志

在检验以前,每批钢筋应具有易识别的标签。标签上标明制造商试验号及批号,或者其它识别该批钢筋的证明。

三、  试样及试验

1. 一般要求

(1)钢筋应按《金属材料室温拉伸试验方法》(GB/T 13239—2006)、《金属材料弯曲试验方法》(GB/T 232—1999)及《焊接接头冲击试验方法》(GB 2650—89)、《焊接接头拉伸试验方法》(GB/T 2651—89)的规定进行屈服点、抗拉强度、延伸量和冷弯试验及焊接性能试验,或经监理工程师批准,采用相应的国际上采用的标准。

(2)钢筋必须按不同钢种、等级、牌号、规格及生产厂分批验收,分别堆存,且应立牌以便于识别。

(3)所有钢筋的试验必须在监理工程师同意的试验室进行。

2. 钢筋试验

(1)提供钢筋时应有工厂质量保证书(或检验合格证),否则,不得使用于工程中。当钢筋直径超过12mm时,应进行机械性能及可焊性性能试验。

(2)进场后的钢筋每批(同品种、同等级、同一截面尺寸、同炉号、同厂家生产的每60t为一批)内任选三根钢筋,各截取一组试样,每组3个试件,一个试件用于拉伸试验(屈服强度、抗拉强度及延伸率);一个试件用于冷弯试验;一个试件用于可焊性试验。

(3)如果有一个试件试验失败或不符合表403-1要求,另取两个试件再做试验。如果两个试件中有一个试验结果仍不符合要求,则该批钢筋将不得接收,或根据试验结果由监理工程师审查决定降低级别用于非承重的结构。

四、钢筋的储存、加工与安装

1. 钢筋的保护及储存

(1)钢筋应贮存于地面以上0.5m的平台、垫木或其它支承上,并应保护它不受机械损伤及由于暴露于大气而产生锈蚀和表面破损。

(2)当应用于工程时,钢筋应无灰尘、有害的锈蚀、松散锈皮、油漆、油脂或其它杂质。

(3)钢筋应无有害的缺陷,例如裂纹及剥离层。只要用钢丝刷刷过的试样的最小尺寸、截面拉伸性能符合规定的钢筋尺寸及钢筋级别的力学性能要求,则该钢筋的铁锈、表面不平整或轧制鳞皮不能作为拒收的理由。

2. 钢筋整直

盘筋和弯曲的钢筋,采用冷拉方法调直钢筋时,R235级钢筋的冷拉率不宜大于2%;HRB335、HRB400牌号钢筋的冷拉率不宜大于1%。

3. 钢筋的截断及弯曲

(1)除监理工程师书面指示外,所有钢筋的截断及弯曲工作均应在工地工场内进行。

(2)钢筋应按图纸所示的形状进行弯曲。除监理工程师另有许可者外,所有钢筋均应冷弯。

(3)主钢筋的弯曲及标准弯钩应按图纸及《道路工程制图标准》(GB 50162-92)的规定执行。

(4)箍筋的端部应按图纸规定设弯钩,并符合GB 50162-92规定。弯钩直线段长度,一般结构不宜小于5d,抗震结构不应小于10d (d为钢筋直径)。

4. 安设、支承及固定钢筋

(1)所有钢筋应准确安设,当浇筑混凝土时,应选用合理的支承方法将钢筋牢固地固定。钢筋应可靠地系紧在一起,不允许在浇筑混凝土时安设或插入钢筋。

(2)桥面板钢筋的所有交叉点均应绑扎,以避免在浇筑混凝土时钢筋移位。但两个方向的钢筋中距均小于30cm时,则可以隔一个交叉点进行绑扎。

(3)用于保证钢筋固定于正确位置的预制混凝土垫块,其形状大小应为监理工程师所接受,同时,其形状应避免混凝土垫块在浇筑混凝土时倾倒。垫块混凝土的骨料粒径不得大于10mm,其配合比应符合第410节的要求,其强度应与相邻的混凝土强度一致。用1.3mm直径的退火软铁丝预埋于垫块内以便与钢筋绑扎。不得用卵石、碎石或碎砖、金属管及木块作为钢筋的垫块。

(4)钢筋的垫块间距在纵横向均不得大于1.2m 。桥面板混凝土的钢筋安设按照图纸要求,在竖向不应有大于±5mm的偏差。

(5)任何构件内的钢筋,在浇筑混凝土以前,须经监理工程师检查认可。否则,浇筑的混凝土将不予验收。

(6)钢筋网片间或钢筋网格间,应相互搭接使能保持强度均匀,且应在端部及边缘牢固地联接。其边缘搭接长度应不小于一个网眼。

(7)安装在预制构件上的吊环钢筋,只允许采用未经冷拉的R235级热轧钢筋。

5. 钢筋的代用

(1)经监理工程师同意,屈服强度高的钢筋可以代替屈服强度低的钢筋,但代用钢筋总面积和总周长均不得小于原设计图所用钢筋。

(2)除非经监理工程师同意,不得以多种直径的钢筋代替原有同一直径的钢筋。

(3)代用钢筋的净距应遵守《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG D62-2004)第六章的规定。

(4)光圆钢筋不得代替带肋钢筋。

(5)由于钢筋代用而增加的费用应由承包人负责。

(6)代用的钢筋层数不得多于原图纸规定钢筋层数。

 

 

STEEL BAR

I. SCOPE

This work consists of the supply, testing, storing, processing and installing of steel bars employed in the bridge and structure constructions.

 

II. MATERIALS

lGeneral Requirements

(1) Ribbed steel bars shall conform to the stipulations of Hot Rolled Ribbed Steel Bars for Reinforced Concrete (GB 1499-1998), plain round bars shall conform to the stipulations of Hot Rolled Plain Round Bars for Reinforced Concrete( GB 13013-1991) The major dynamic performance and fabrication property for steel bars are listed in Tab1e-1 below:

Types and Marks

R235

HRB335

HRB400

Diameter(mm)

8~20

6~25

28~50

6~25

28~50

Minimum Yield Strength(MPa)

235

335

400

Minimum Tesile Strength(MPa)

370

490

570

Elongation δ5 (%)

25

16

14

Cold-bending(180°)

internal diameter

2.5d

3d

4d

4d

5d

Table -1 Main Dynamic and Fabrication Property of Reinforcing Steel

Note: d is the nominal diameter of bars.

(2) Other steel bars in accordance with the above standard and used internationally may be used if approved by the Engineer.

(3) Steel plates for reinforcement cages or skeletons and structural steel for other items shall conform to the requirements of the drawing and the property of Q 235 steel  (GB/T 700-1988) of Structural Carbon Structure.Structural steel shall be tested in the same way as reinforcing steel.

2Test Certification

Three copies of a factory test report shall be provided to the Engineer from each lot of steel proposed for use on the project,unless otherwise approved by the Engineer.This report shall be signed by a person with legal authority (such as the quality supervision department of the government) who can bind the manufacturer of the steel product and supply the following information:

(1)   Method for rolling reinforcing steel bars;

(2)   Identification of each furnace or each lot of reinforcing steel bars(including tensile test, bending test results);

(3)   Physical and chemical property of each furnace or each lot of reinforcing steel bars.

3Identification

The bars in each lot shall be legibly tagged before being offered for inspection. The tag shall show the manufacturer’s test number and lot number or other designation that will identify the lot of steel.

 

III. SAMPLES AND TESTING

l. General Requirements

(1) Reinforcing bars shall be tested for yield point, tensile strength, elongation, cold bending and welding property in accordance with Test Method for Metal Materials Stretching under Room Temperature (GB/T228-2002), Sampling Position and Specimen Preparation for Dynamics Property Test for Steel or Steel Products (GB/T 2975-1998), Bending Test Method for Metal Materials (GB/T 232-1999) and Impact Test Method for Welding Joint(GB 2650-89), Tensile Test Method for Welding Joint (GB 2651-89), or use the related international stipulations approved by the Engineer.

(2) Reinforcing bars shall be accepted in batches according to different assortments, grades,marks,sizes and manufacturers, and piled up separately with indication signboards.

(3) All tests for reinforcements must be carried out in laboratory approved by the Engineer.

2. Reinforcement Test

(1) The reinforcement shall be accompanied by factory quality guarantee(or test certificate, otherwise it shall not be used in the work.When the diameter exceeds 12mm, tests of mechanical property and weldability shall be performed.

(2) Three sets(each three specimens)of samples will be taken respectively from three bars of each lot(every 60 t with an identical variety, grade, section size, furnace number manufacturer is one lot).From each set of sample,one specimen shall be subjected to a tensile test (yield point,tensile strength and elongation rate), one is used for cold bending test,the other is used for weldability test.

(3) If any specimen fails a test or does not conform with the requirements of Table 403-l,two more specimens will be taken for a repeated test. If either of the two specimens also does not conform to the requirements of Table 403-1,the steel will be rejected,or lowered to grade conforming to the test results and assigned to non-supporting structures,as examined and determined by the Engineer.

 

IV. STORAGE, PROCESSING AND ERECTON OF REINFORCEMENT

1Protection and Storage of Reinforcement

(1) Reinforcement shall be stored 0.5m above the ground on platforms,skids,or other supports and shall be protected from mechanical damage,rusting and surface deterioration caused by exposure.

(2) When used in the work, reinforcement shall be free from dust,detrimental rust, loose scale,paint, grease,oil,or other foreign matters.

(3) Reinforcement shall be free from harmful defects such as cracks and laminations. Rust,surface seams, surface irregularities or mill scale shall not be cause for rejection. Provided that the minimum dimension,cross-sectional area and tensile property of a hand wire-brushed specimen meet the physical requirements for the size and grade of steel reinforcement specified.

2Bar Straightening

As to coiled and crooked bars, bars after cold stretch straightening the cold stretch rate of grade l bars shall not be greater than 2%; and cold stretch rate of HRB335, HRB400 bars shall not be greater than 1%.

3Bar Cutting and Bending

(l) All cutting and bending of reinforcing bars shall be carried out in an on-site fabrication shop, unless instructed in writing by the Engineer.

(2) Bars shall be bent according to the shape shown on the drawing. Unless otherwise approved by the Engineer, the cold-bend shall be carried out for all bars. The partial bars embedded in the concrete shall not be bend in site.

(3) Main reinforcing bar bends and standard end hooks shall be as shown on the drawings and conform to stipulations in Standard for Road Engineering Drawings (GB50162-92).

(4) Hooks shall be provided at the free end of stirrups as shown on the drawings, and conform to stipulations in GB50162-92. The terminal length outside of the curvature for a hook shall not be less than 5d for common structures, nor less than 10d for  earthquake resisting structures (d is the nominal diameter of the bar).

4ErectionSupporting and Fastening

(l) All reinforcing bars shall be accurately placed,and during the placing of concrete,firmly held by supports.Reinforcing bars shall be securely fastened together.Laying or driving bars into the concrete during placement will not be allowed.

(2) In bridge decks, reinforcing bars shall be tied together at all intersections so as to prevent displacement due to concreting.Where the spacing of bars is less than 300mm in both directions,alternate intersections may be tied.

(3) Precast concrete cushion block required for ensuring that the reinforcement is correctly positioned, shall be of a shape acceptable to the Engineer,and designed so that they will not overturn when the concrete is placed.They shall be made of concrete with aggregate of size not exceed 10mm and the mix proportions shall comply with Section 410 to produce the same strength as the adjacent concrete.Soft annealed iron wire of l.3mm diameter shall be emmbedded into the blocks for purpose of tying it to the reinforcement.The use of pebbles,pieces of broken stone or brick,metal pipe and wooden blocks for supports shall not be permitted.

(4) The supports of reinforcing bars shall not be spaced more than 1.2m apart transversely or longitudinally.The placement of deck reinforcing bars shall not deviate more than ±5mm in the vertical direction,from the position shown on the drawings.

(5) Before placing, the bars in any structural members shall be approved by the Engineer. Otherwise, the placed concrete will not be accepted.

(6) Sheets of mesh or bar mat reinforcement shall overlap each other sufficiently to maintain a uniform strength and shall be securely fastened at the ends and edges. The edge lap shall not be less than one mesh in width.

(7) The slinger rings used on precast concrete members shall only be made with  uncoldstretched grade R235hot rolled steel bars.

5Substitutions of steel bars

Substitution of reinforcements shall be permitted by the Engineer, and shall comply with following requirements:

(l) As approved by the Engineer,the lower yielding strength bars may be substituted by the higher ones; however,the overall area and overall perimeter and number of bars of substiting bars shall not be less than those of the original bars shown on the drawings.

(2) Unless with the approval of the Engineer,  the original bars with identical diameter shall not be substituted by bars with various diameters.

(3) The clear spacing of substituted bars shall conform to Chapter 6 of Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004).

(4) Substitution with round bars for ribbed bars shall not be allowed.

(5) The expenses due to substitutions are at the cost of the Contractor.

(6) Number of layers of substituted bars more than the original number of layers stipulated on the drawings shall not be allowed.

 



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