Research On Flexural Performance Of Concrete Members Strengthened By UHTCC

Ultra high toughness cementitious composites(UHTCC for short)is a kind of fiber reinforced cementitious composite with significant strain hardening property and multi-cracking characteristic.The application of UHTCC in the concrete structures can improve the bearing capacity,crack resistance and durability.In this paper,the experiments,theoretical calculation and simulations were carried out to investigate the performance of UHTCC structures reinforced by UHTCC.The main contents are summarized as follows:(1)Based on the damage plasticity model in ABAQUS,the constitutive relationship of UHTCC and other parameters were reasonably determined.The model was adopted to simulate the mechanical properties of UHTCC specimens under uniaxial compression and tensile load.The model of UHTCC/concrete composite beam was established to analyze the flexural properties.The numerical results were in good agreement with those obtained from tests and literature.The simulation results showed the damage and crack development of UHTCC and concrete,which indicated that UHTCC has the ability of dispersing crack into harmlessly ones.(2)The calculation formula for flexural capacity of composite beam is deduced The bending tests of composite beams strengthened with different methods were carried out.The results showed that UHTCC can improve the ultimate capacity and crack resistance.With the strengthened reinforcement ratio increasing,the ultimate capacity was improved,but the interfacial failure between UHTCC and concrete occurred which caused the composite beams destroyed prematurely.Compared with test results,it is discussed that the calculation method was reliable.(3)The calculation formula for UHTCC members under eccentric tension and eccentric compression was proposed.Combined with specific engineering,the numerical analysis was carried out to simulate the concrete faced rockfill dam strengthened with different thickness of UHTCC.The simulation result indicated that UHTCC can improve the mechanical behavior and crack resistance of UHTCC members under tension and bending moment.The theorical results were in agreement with those obtained by numerical simulation.(4)The four-point bending test for shape memory alloy/UHTCC was carried out to investigate the effect of amount of alloy and pre-strain on flexural capacity,deflection and crack width.The test results showed that shape memory alloy can improve the flexural capacity of UHTCC specimens,the deflection and crack width decreased after heat treatment.Increasing the amount of alloy and applying pre-strain is helpful for the self-repairing performance.