Research On Flexural Behavior Of Ultra-high Strength Concrete Pole

Concrete pole is a widely used tower structure in the field of overhead line in our country.Due to the weakness of low bending strength and large self-weight,the pole made of ordinary concrete has a relatively short service life and needs much maintenance work.Ultra-high strength concrete is a new cement-based material,which has good mechanical properties and is seldom used in concrete pole structure.In this thesis,the mechanical properties of ultra high strength C120 concrete materials were studied by tests.Then the C120 was applied to the pole whose mechanical performance test was carried out.A compare of mechanical properties between the ultra strong pole and the ordinary pole was conducted,and the corresponding finite element simulation analysis was carried out.The main research contents and results are as follows:(1)The mixing ratio of C120 concrete was designed,and the research of the influence on its compressive properties by coarse and fine aggregate,steel fiber and other materials was carried out.The results show that steel fiber and quartz sand can improve the compressive strength of ultra-high strength concrete.(2)Centrifugal molding process is adopted to apply C120 ultra-high strength concrete material in pole structure.The cantilever test method was introduced to conduct the bending crack inspection in the pole deflection test.Three poles made of of C120(50 mm thickness),C120(40 mm thickness)and C50(50 mm thickness)were tested respectively,and results proved that the C120(40 mm thickness)pole meets the bending capacity requirement and has a light weight,which indicates its performance advantage over other choices.(3)The full scale test of the C120 pole was carried out.The design loads of three working conditions were considered respectively,and no abnormality was found in the pole.Furthermore,a certain range of overload capacity was observed.(4)The ABAQUS software was used to analyze the C120 pole and C30 pole and compare their internal forces and deformation under normal operation and accident break.The results show that the maximum Mises stress of reinforcement and concrete in C120 pole is less than the yield stress of the material,and the maximum deflection is larger than that of C30 pole.This indicates that the C120 pole has a better bending capacity.