JPKIC 结构设计原理 jhepniciplestucturedesg Foreign countries,concrete cylinder specimens are often used to determine concrete compressive strength For example,the United States,Japan and the European Concrete Association,(CEB)with diameter of 6 inches (152mm),12 inches (305 mm)standard cylinder compressive strength of specimens as indicators of axial compressive strength,denoted by f.Below the C60 concrete the relationship between the cylinder compressive strength and cube compressive strength value of fu.k can be converted: F”。=0.79fuk fuk increases the compressive strength after more than 60N/mm2, the ratio of fuk (that is,the coefficient in the formula)will be raised.CEB-FIPMC-90 provides:for C60 concrete,the ratio is 0.833;for C70 concrete,the ratio is 0.857;for C80 concrete,the ratio is 0.875
Foreign countries, concrete cylinder specimens are often used to determine concrete compressive strength For example, the United States, Japan and the European Concrete Association, (CEB) with diameter of 6 inches (152mm), 12 inches (305 mm) standard cylinder compressive strength of specimens as indicators of axial compressive strength, denoted by fc . Below the C60 concrete the relationship between the cylinder compressive strength and cube compressive strength value of fcu, k can be converted: • fcu,k increases the compressive strength after more than 60N/mm2 , the ratio of fcu,k (that is, the coefficient in the formula) will be raised. CEB-FIPMC-90 provides: for C60 concrete, the ratio is 0.833; for C70 concrete, the ratio is 0.857; for C80 concrete, the ratio is 0.875. F’c =0.79fcu,k
JPKIC 结构盘计原黑 2.Concrete Prism strength (axial compressive strength) Definition:a true reflection of compressive strength of concrete structure,which is measured by a 150mm X150mm X300mm prism as the standard sample. Note that:the sample production,curing and load test method are same with the cubic specimen (2)Conversion of standard value of axial compressive strength and cube compressive strength is: To =0.88afcuk Note that:C50 and the following concrete,a=0.76;C55 ~C80 concrete,for C40 concrete a=0.76 to 0.82 considering concrete with brittle,reduction coefficient is used for C40~C80 as 1.0~ 0.87,the interpolation is employed for middle values
2. Concrete Prism strength (axial compressive strength) Definition: a true reflection of compressive strength of concrete structure, which is measured by a 150mm ×150mm ×300mm prism as the standard sample. • Note that: the sample production, curing and load test method are same with the cubic specimen (2) Conversion of standard value of axial compressive strength and cube compressive strength is: • Note that: C50 and the following concrete, a= 0.76; C55 ~ C80 concrete, for C40 concrete a= 0.76 to 0.82 considering concrete with brittle, reduction coefficient is used for C40 ~ C80 as 1.0 ~ 0.87, the interpolation is employed for middle values. ck cu ,k f = 0.88f
JPKIC 结构计原黑 3.Axial tensile strength (, is an important indictor for cracking performance in design of RC elements Expression: 1.= 18 fk=0.88×0.395Bf.0(1-1.645δ150)°49 where δm50 variation of coefficient of of compressive strength specimens with a side length of 150mm
3. Axial tensile strength ( ) is an important indictor for cracking performance in design of RC elements t f 1 1 ~ 8 18 t c f f = t f 0.55 0.45 , 150 0.88 0.395 (1 1.645 ) tk cu k fl f f = − fl150 —— variation of coefficient of of compressive strength specimens with a side length of 150mm. Expression: where
JPKic 结构设计原理 The principle of structure design Test methods Direct axial stretching method Splitting test method 钢筋 钢筋 150 200 人150 100 500 Direct axial stretching method 拉++压 2 Splitting test method
Test methods Direct axial stretching method Splitting test method 钢筋 钢筋 拉 压 + Direct axial stretching method Splitting test method
JPKIC 结构设计原理 Thepniciplestncturedesgn Summary How to use the three strength indicators The concrete strength indicators are o The cube strength is representative of all the basic values of mechanical index
How to use the three strength indicators ⚫The concrete strength indicators are ⚫ The cube strength is representative of all the basic values of mechanical index cu f c f t f