Study On Shear Bearing Capacity On Beams Of Steel Fiber Reinforced Concrete With Recycled Aggregates

There is a lack of natural resources in our country,and construction waste piles up like mountains.It is very meaningful to study how to make rational use of these demolition waste materials.In order to recycle these building waste materials and apply them to engineering structures,10 reinforced steel fiber reinforced recycled concrete beams with the same matrix concrete and different steel fiber fraction(0.0.8%,1.2%,1.6%.2.0%) were tested.Matrix recycled concrete is composed of 16-20 mm natural coarse aggregate,5-16 mm recycled coarse aggregate and 0-4.75 mm recycled fine aggregate.Steel fibers are made of Ingot Milling profiled steel fibers.The effects of different volume fractions of steel fibers on cracking load,ultimate load,stirrup strain in shear span,concrete strain in shear compression zone and maximum width of inclined cracks of test beams are analyzed by experimental data.Statistical analysis and truss-arch model are used to calculate the shear capacity of test beams to verify the applicability of the formula.The main conclusions are as follows:(1)The shear-span ratio of the tested beams is 2,and the failure modes are shear-compression failure,which is the same as that of ordinary steel fiber reinforced concrete beams;(2)In the process of shearing,the strain of stirrups in shear span and concrete in shear compression zone increases with the increase of steel fiber volume ratio,while the width of inclined cracks decreases with the increase of steel fiber volume ratio;(3)The addition of steel fiber increases the cracking load and ultimate load of the mixed recycled concrete beam.When the steel fiber volume fraction=2.0%,it increases by 42.86%and 30.68%respectively;(4)Combining the existing shear calculation formulas of ordinary reinforced steel fiber reinforced concrete beams and the reinforcement coefficient ax of steel fiber reinforced composite regeneration fitted according to the experimental data,the calculated values are close to the measured values.The calculated values of the shear forlulas in the current Code for Design of Concrete Structures and Technical Regulations for Fiber Reinforced Concrete in China are smaller than the measured values,and have a certain safety reserve.