《第章 混凝土结构用材料的性能（Chapter . Properties of concrete structures used in materials）.doc》由会员分享，可在线阅读，更多相关《第章 混凝土结构用材料的性能（Chapter . Properties of concrete structures used in materials）.doc（31页珍藏版）》请在三一文库上搜索。
1、第1章 混凝土结构用材料的性能（Chapter 1. Properties of concrete structures used in materials）In this paper, by foot Tian snake contributionThe PPT document may not have a good browsing experience at the WAP end. It is recommended that you choose TXT, or download the source file to the native view.Chapter 1 materi
2、al properties of concrete structureThe concrete structure is made of reinforced concrete and concrete. In order to properly design the concrete structure. In order to design the concrete structure reasonably, the stress performance of concrete and steel reinforcement is needed. Understand the mechan
3、ical properties of concrete and steel. The solution of the mechanical properties, interaction and common work of concrete and steel mechanics, soil and steel, is the basis of the analysis and design of concrete structure components. Basis of analysis and design. 1 bar1.1 the varieties and properties
4、 of steel a, classification According to the machining method points: 1. According to the processing method: hot rolled steel, heat treatment in steel, high strength steel wire, steel strand in the steel, hot rolled steel, heat treatment, high strength steel wire, steel strand, cold working steel ba
5、r By using utility cent: ordinary reinforced, (2) according to the using purpose: ordinary reinforced, prestressed reinforcement According to chemical composition points: low carbon steel, (3) according to the chemical composition points: low carbon steel and ordinary reinforced according to the mec
6、hanical properties of low alloy steel, steel has obvious yield point, 4. According to the mechanical properties of points: have obvious yield point steel, no significant yield Some steel According to the steel shows that shape points: plain bar, 5. According to the steel shows that shape points: smo
7、oth steel and deformed steel(1) hot rolled steel hot-rolled steel hot rolled steel is steel with ordinary low carbon steel (carbon content is not greater than 0.25 hot rolled steel mills with ordinary low carbon steel carbon content is not more than and ordinary low alloy steel (alloy elements made.
8、 No more than %) and ordinary low alloy steel alloying elements is not more than %). And ordinary low alloy steel alloy elements are not greater than 5%The hot rolled steel is divided into I, II, III and IV, respectively, according to its carbon content.The commonly used types are shown. The commonl
9、y used types, symbols and diameters are shown in table 1-1. As shown inThe type of hot rolled steel, the type of hot rolled steel, the symbol and diameter range are usedStrength grade code HPB235 HRB335 HRB400 RRB400D/mm6 20, 20, 6 50, 50, 6 50, 8 40Q235 (low carbon steel) Q235 (low carbon steel) 20
10、MnSi (low alloy steel) 20MnSi (low alloy steel) 20MnSiV, 20MnSiNb, 20MnTi low alloy steel) (low alloy steel) K20MnSi (low alloy steel) K20MnSi (low alloy steel)For hot rolling plain bar, HPB235 for hot rolled smooth steel, ordinary steel hot rolled deformed bars, HRB335 and HRB400 hot rolled deforme
11、d bars, ordinary reinforced RRB400 is steel heat treatment steel heat treatment is the yield strength of steel bar in wear water cooling after rolling, HRB335 rebar in water cooling after rolling, then using the core residual heat quenching water scale on the surface of steel and deformed steel temp
12、ering treatment. The hardened steel surface of the rebar and the hardened steel. Its performance is close to the steel bar,The grade steel bar is stable, and the steel bar of HRB400 is not equal to that of the HRB400 steel bar, but the strength of the steel reinforcement is reduced, so the applicati
13、on scope is limited. The strength of the reinforcement is reduced, so the application scope is limited.In the construction of highway bridge, it is said that in the construction of highway bridge, the steel bar of hot rolled face is used for R235, and the residual heat processing steel is indicated
14、by KL400. The diameter of the steel bar does not indicate that the steel mills of any diameter in this range are produced. Steel mills are produced. Steel bar diameter is 6 mm, 6.5 mm, 8 mm, 8.2 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm and 22 mm, 25 mm, 28 mm, 32 mm, 36 mm, 40 and 50 mm, mm. In
15、this case, d = 8.2 mm steel bar only applies to steel design with longitudinal ribs. In the design, choose the steel bar in the diameter of table 1-1 and the diameter provided above. The reinforcement is mainly used for the selection of reinforcement. The steel bar with diameter greater than 40 mm i
16、s mainly used in a large concrete structure of the dam. In the concrete structure. When using a steel bar with a diameter greater than 40 mm, it should be able to rely on engineering experience. Working experience in engineering.Strength of reinforcement and deformation can be obtained by tensile te
17、st stress - strain curveTensile test of reinforcementPa.P = A sigmalL epsilon = lPThere is a sigma - epsilon curve with a clear flow of steelOa - elastic stageSigma (N/was)Ft fyThe flow ofdUltimate strengthCD - strengthening stage e DE - neck contractionThe yield strengthProportional limitA b cSigma
18、 a - proportional limit epsilon sigma b - yield strength sigma d - ultimate strengthFigure 1 oThe sigma - epsilon curve of the bar is not obviousSigma 0.2 sigma (N/was)o0.2%Epsilon.Figure 2Sigma 0.2 - conditional yield strengthIn addition to the strength of reinforcement, it should have a certain pl
19、astic deformation ability, and the plasticity of the steel is usually measured in terms of elongation delta and cold bending performance.L 2? So l1 times 100% of the elongation delta equals l1The cold bend is a steel roller with a diameter of d, a steel roller with a diameter of d. It bends into a c
20、ertain Angle without breaking, and is qualified.The four main mechanical indicators of steel reinforcement:Yield strength, ultimate strength, elongation and cold bending performance. Yield strength, ultimate strength, elongation and cold bending performance.The yield strength of soft steel with obvi
21、ous yield steps is based on strength design. The yield strength of the hard steel for the non-obvious yield step is based on the strength design.The definition of sigma 0.2 is to take the stress sigma 0.2 as the nominal yield point corresponding to the residual strain epsilon = 0.2%. It is often cal
22、led sigma 0.2 = 0.8 fsu. Elongation:L2? So l1, delta is going to be equal to 100%, l1, right? Delta 5, l1 is equal to 5d? ? Delta 10, l1 = 10dThe Angle of the cold bending of the bent diameterCold bending performance:Cold-processed steel rebar is the steel bar that is used for the processing of hot
23、rolled bar under normal temperature. Reinforcing steel bars for processing. There are four kinds of cold drawing, cold drawing, cold rolling and cold rolling. Cold drawn, cold drawn, cold rolled and cold rolled. The aim is to improve the strength of steel bar to save steel. However, the strength of
24、reinforcement is improved to save steel. But, after cold - processing reinforcement in strength increased at the same time, the elongation decreased significantly, after the reinforced in strength increased at the same time, the elongation decreased significantly, except for the cold drawn steel bar
25、 still has obvious yield point, in addition to the cold drawn steel bar still has obvious yield point, the rest of the cold No obvious yield point of steel bars and yield level. The steel bars have no obvious yield points and yield steps. (1) cold drawn steel(2) cold-drawn steel bar cold-drawing is
26、a hard alloy wire that has been pulled through the steel bar with a small diameter. The steel bar is subjected to longitudinal tension and lateral pressure, the die (FIG. 1-9). At this time, the steel bar is subjected to longitudinal tension and lateral pressure, the internal structure changes, the
27、section decreases and the length increases. After several cold drawing, the structure changes, the section decreases and the length increases. After several cold drawing, the strength of reinforcement is much higher than before, but the plasticity is significantly reduced. The strength of reinforcem
28、ent is much higher than before, but the plasticity is significantly reduced. There is no obvious yield point (figure 1-10). Cold drawing can improve the tensile strength and compressive strength of steel bar simultaneously. Degree and compressive strength.Cold-drawn low carbon steel wire is light ci
29、rcular steel wire, cold drawing and low carbon steel wire is light round steel wire, diameter is 3 mm, 4 mm, 5 mm, intensity is 550 MPa, 650 MPa and 750MPa 3 kinds. In this paper, 550 cold-drawn steel wire is used as non-prestressed steel bar, MPa cold-drawn steel wire is used as non-prestressed ste
30、el bar, and the rest is used as prestressed steel reinforcement. (3) the cold-rolled ribbed steel cold-rolled ribbed steel in low carbon steel or low alloy steel as raw materials, low alloy steel as raw material, at room temperature rolling and surface with longitudinal ribs and crescent lines cross
31、 rib steel bar (figure 111). Its ultimate strength is similar to that of cold-drawn low carbon steel wire, but the elongation ratio is significantly higher than that of cold-drawn carbon steel wire. The low carbon steel wire has obviously improved. Using this kind of steel bar to replace ordinary mi
32、ld steel and cold-drawn steel wire, it can improve the stress performance of the components in normal use stageSave steel. Save steel. The diameter of the cold-rolled rib bar is from 4 12mm, and it is changed by 0.5mm. Its tensile strength is 550MPa, 650MPa, 800MPa, several. Among them, 970MPa and 1
33、170MPa. Among them, 550MPas cold-rolled rib bar is used as an unprestressed bar, and the rest is used as prestressed reinforcement. Used as a non-prestressed bar, the rest is used as prestressed reinforcement. (4) cold rolled and twisted steel is the raw material, cold rolled and twisted reinforceme
34、nt is the raw material with hot rolled steel HPB 235. The process parameters determined by the process parameters are determined.The cold reinforcing steel bar with continuous spiral shape is twisted by the twisting of the steel and cold rolling mill. (1-12). Its specifications according to the raw
35、material 6.5 in diameter, 8, 10 and 12 respectively r r r, 8, 10 and 6.5 r 12, tensile strength standard values of 600 N / 2 mm.Cold drawn low carbon steel wire, cold drawn low carbon steel wire, cold rolled rib bar and cold rolling steel bar have special design and construction procedures for desig
36、n and construction. Design and construction procedures for design and construction. 1.1.2 the concrete structure is required for the performance of the steel bar. 1. The high strength of the steel bar can be used to save the steel, and the high strength reinforcement can save the steel and obtain be
37、tter economic benefits. Benefits. 2. The plastic is good Asked the deformation of the steel bar in front of the fracture have enough requirements reinforcement have enough before fracture deformation, can give a person with damage prediction Therefore, we should ensure that the elongation and cold b
38、ending steel performance is qualified. Trillion. Therefore, it is necessary to ensure the elongation and cold bending of the reinforcement.3. Weldability is good in many cases, in many cases, the connection between the extension of the steel bar and the steel bar should be welded. No crack or excess
39、ive deformation of steel bar after welding, welding. No crack and excessive deformation after welding, ensure that the joints are good after welding. The joints have good performance. 4. In order to ensure the strength of the reinforcement can be fully utilized and guaranteed to work together with t
40、he concrete, there should be sufficient adhesion force between the two. There should be sufficient adhesion between the two. In the cold region, there are some requirements for the low temperature performance of the steel bar. In cold areas, there is also a requirement for the low temperature perfor
41、mance of steel bars. 1.1.3 reinforced the selection principle of 1. The steel bar in reinforced concrete structures and prestressed concrete structure reinforcement, non prestressed reinforcement should be preferred HRB400 and HRB335 reinforced, to save steel consumption, improve the quality of the
42、building structure in our country. In addition, to improve the quality of building structure in our country. In addition to that,HPB235 and RRB400 hot rolled bars can also be used as well as low strength grade cold drawing, cold rolling and cold rolled steel. Lower cold drawing, cold rolling and col
43、d rolled twisted bars.The prestressed steel wire and the high strength steel wire are used, and the prestressed steel wire shall be used in the prestressed steel wire, and the steel wire shall be used for heat treatment. In addition, cold pull can also be used for heat treatment reinforcement. In ad
44、dition, the steel bar and the strength of the high - grade cold drawn carbon steel wire and cold rolled twisted steel. Steel and steel bars with high strength and low carbon steel wire and cold rolled twisted bars. In the construction of highway bridge, it is also possible to use the refined thread
45、reinforcement. In the highway bridge and culvert project, the refined thread steel can be used. 2concreteThe composition structure of concrete is composed of cement, stone, sand and water according to certain matching ratio, and the artificial stone made after solidification.The foundation of elasti
46、c deformation of cement cementing of aggregate cementThe strength and deformation of concrete varies with time and environment.2.2 under unidirectional stress of concrete strength of unidirectional stress state of concrete strength index, to analyze strength of steel reinforced concrete structures i
47、s, to establish the important basis of strength theory formula. With the cement concrete strength value of the size of the label, water-cement ratio, aggregate properties, production methods, curing conditions and the experiment test pieces, test method of size and shape or load duration, etc. Have
48、the very big relations.Compressive strength of concrete1. The strength of the cube is influenced by the strength of the compressive strength fcu: the size, temperature, humidity and test method of the cube. Effect of size effect: fcu (150) = 0.95 fcu (100) fcu (150) = 1.05 fcu (200)Strength grade of concrete: 150 x 150mm cubic test block made from standard production method, with a 95% guarantee rate, measured by standard test method in the age of 28 days. Commonly used grade: C7.5, C10, C15, C20, C25, C30, C35, C40, C45, C55, C60.2. Axis compressive strength (prismatic