Research On Explosion Resistance And Damage Monitoring Of Steel Fiber High Strength Concrete Slab

Steel fiber reinforced high-strength concrete has not only the advantages of high-strength concrete in compression and corrosion resistance,but also the advantages of steel fiber in tensile,shear and bending resistance.It is often used as the main material of building structures.However,with the rapid development of industry and the aggravation of regional conflicts,explosion accidents and terrorist attacks occur frequently,and the constructions are damaged seriously under the impact of explosion.Therefore,it's should be considered the anti explosion performance of steel fiber reinforced high-strength concrete.On the basis of the anti-detonation theory of concrete structure,carried out contact and non-contact explosion experiments above on SFRC slabs with the volume fraction of 0%,0.6%,1.2% and 1.8% of steel fiber,additionally,numerical simulation technology is also used to research.The main contents are as follows:(1)Dynamic response experiment of SFRC slabs under explosion.The total response process of SFRC slab with different fiber volume content under explosive is tracked by using acceleration,strain gauge and displacement meter.Research revealed that when the strength of concrete matrix is fixed,the acceleration,strain and deflection values of the back of SFRC slab with steel fiber are always smaller than those of SFRC slab without fiber,and the addition of fiber can significantly enhance the tensile performance of high-strength concrete,also can delay the cracking of concrete and disperse the energy of explosion wave.By analyzing the macroscopic failure mode of the slab,the volume of explosion pit and peeling pit is fitted by polynomial function,which is also proved.(2)Mesoscopic numerical simulation of anti-explosion of SFRC slabs.Based on the random distribution characteristics of steel fiber in the matrix,a three-dimensional meso numerical model including steel fiber,steel bar and concrete medium is established with the help of MATLAB and ANSYS/LS-DYNA.The correctness and effectiveness of the meso finite element model are verified by experiments,and the influence of length diameter ratio,plate thickness and matrix strength change on the anti explosion performance of the structure is further analyzed.Under the same condition of fiber volume content and explosion form,the anti explosion performance of the structure increases with the increase of fiber length diameter ratio,plate thickness and concretestrength,the damage degree decreases gradually,the volume of crater on the blasting face changes slightly,but the volume of back peeling pit decreases obviously.The comprehensive research shows that the anti explosion performance of the structure is better when the fiber length diameter ratio is60,thickness is 11 cm,and the concrete strength is 70 MPa.(3)Damage monitoring of SFRC slabs.The embedded piezoelectric intelligent aggregate is introduced to monitor the damage state of SFRC board in each explosion,and compared with ultrasonic test results at the same time,using the theory of wavelet packet energy analysis to calculate damage index,found that the steel fiber reinforced high strength concrete antiknock ability is improved obviously,the piezoelectric intelligent structure of aggregate is also suitable for monitoring the dynamic damage.