| Corrosion of steel bars is the main reason that affects the durability of reinforced concrete structures.Using FRP bars instead of steel bars can fundamentally solve the problem of deteriorating durability of reinforced concrete components caused by corrosion of steel bars.Although FRP material has the advantages of high strength and corrosion resistance,due to its small elastic modulus,FRP ribs will suffer from wide cracks and large deformation during loading.By adding steel fibers in the concrete matrix,cracks in the concrete components can be effectively inhibited and the deformation resistance of the components can be improved.For this reason,this paper carries out the shear test study of GFRP stirrups concrete beams with steel fiber added,and compares and analyzes the problems such as bearing capacity,deformation and crack development of GFRP stirrups concrete beams under different steel fiber content.The main research contents and conclusions as follows:1.The shear resistance test of five GFRP stirrups steel fiber reinforced concrete beams was carried out,and the effects of different shear span ratio and steel fiber content on the shear capacity and crack development of the components were analyzed.Compared with the test results of GFRP stirrups concrete beams without steel fibers completed before the research group,the results show that the cracking loads of the tested beams with different steel fiber contents have been improved,and crack development has been effectively suppressed.2.The three-dimensional spherical model was used to quantitatively analyze the steel fibers distributed in the matrix in a random manner,and then the contribution value of the steel fibers in the model against the shear capacity was obtained.At the same time,based on the truss-arch model theory and the conditions of deformation coordination,the formula for the shear capacity of GFRP stirrups steel fiber reinforced concrete beam is deduced.Compared with the test results,the coefficient of variation of the ratio of the actual measured value to the calculated value of the formula is 0.11,and the average value is 1.06.It can be seen that the measured value is in good agreement with the calculated value.3.Based on the experimental data of GFRP stirrups concrete beams,the calculation formulas of shear-cracking loads of concrete beams are analyzed.Based on this,considering the difference in tensile strength between steel fiber reinforced concrete and ordinary concrete,GFRP stirrupss are proposed.The calculation formula for the cracking load of steel fiber reinforced concrete beams is Compared with thetest value,and the error between the two is small,and it can be used as the formula for calculating the cracking load of such components.4.Based on the analysis of the crack propagation mechanism of steel-concrete reinforced concrete GFRP stirrups,based on the experimental data,regression analysis was performed on the differential coefficient of cracking load,the non-uniformity coefficient of stirrups strain,and the average crack width increase coefficient.Calculation Formula of Maximum Crack Width for Inclined Cross Section of GFRP Stirred Steel Fiber Reinforced Concrete Beams.Comparing the calculated and measured values of the formula,the two are more consistent.5.A GFRP stirrups steel fiber reinforced concrete beam model was established using ABAQUS software.The accuracy of the model was verified by comparing the experimental values with the simulated values.The model was used to expand and analyze the variation of shear-deflection curves under the influence of factors such as concrete strength and stirrups ratio. |
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