Steel Fiber Reinforced Concrete Beams Bearing Capacity Calculation Methods

Steel fiber reinforced concrete has been widely used in every fields of civil engineering since the Design and Construction Specification of Steel Fiber Reinforced Concrete Structures (CECS38: 92) issued in 1992. But the values of calculating parameters specified in this specification are only suited to the strength degree of steel fiber reinforced concrete from CF20 to CF40,it also could not determine the enhancing coefficients of steel fiber to the resistance of reinfoced concrete members by the simple test method of material because these coefficients are not combined with the strength of steel fiber reinforced. Therefore,it is important to improve and revise the current specification, especially adding the design method of shear resistance of steel fiber reinforced concrete beams with strength degree from CF40 to CF80.The research works and conclusions of this paper as following:1. Besed on the test results published over the word of reinforced concrete beams without web reinforcements and with stirrups,the systematically statistical analysis is carried out to set up the fomula of shear resistance of reinforced concrete beams using the uniaxial tensile strength of concrete. It provided the basis of strtistical analysis for shear resistance of steel fiber reinforced concrete beams.2. Based on the test results published over the word of steel fiber reinforced concrete beams without web reinforcements and with stirrups,the effects of steel fiber to shear resistance and the relationship of steel fiber to stirrups are analyzed, the improvements of steel fiber to failure states of reinforced concrete beams without web reinforcements are discussed. It is proposed that the formula of shear resistance of steel fiber reinforced concrete beams based on the model of the current Design and Construction Spectification of Steel Fiber Reinforced Concrete Structures (CECS38: 92), used of the uniaxial tensile strength of steel fiber reinforced concrete, and combined with different formulas specified in current design codes of concrete structures issued by different trades.3. The strtistical analysis results improved that the test scatter reduced due to theapplication of steel fiber. There is not composite enhancing effect to shear resistance of reinforced concrete beams between steel fiber and stirrups. It is identical between the effects of steel fiber on shear resistance of concrete at inclined section of beams and on tensile strength of concrete.4. Steel fiber reduces the size effect of shear resistance of reinforced concrete beams without web reinfocements. The size effect formula is proposed in this paper,it is better agreement with test data.5. It canbe determined the enhancing effect of new steel fiber to shear resistance of beams by the test of tensile strength of steel fiber reinforced concrete,it is important to reduce test cose and increase research efficiency.