Study On The Anti-bend Performance Of UHPC Beams

Ultra-High Performance Concrete,or UHPC,is a new type of cement-based engineering material having ultra-high mechanical properties and excellent durability and super-high toughness,are going to have a broad application prospects in civil engineering structure.This paper takes UHPC beam,the most common component in bridge engineering,as the research object,uses experimental research,combined with theoretical derivation and finite element numerical analysis method,to develop anti-bendperformance study on UHPC beam under different rib conditions.This research is of great scientific significance for the engineering application and popularization of UHPC materials.The main research of this paper is as follows:1?In this paper,six groups of 18 UHPC concrete beams and two C40 reinforced concrete beams with different reinforcement ratios were designed and fabricated,and two-point symmetric loading tests were carried out using an electrohydraulic servo structure test system.The test results show that:(1)In the range of a certain reinforcement ratio,the flexural bearing capacity of UHPC test beam increases along with the longitudinal reinforcement ratio;(2)When a certain reinforcement ratio is exceeded,the bending capacity of the UHPC test beam changes little,and its bearing capacity is almost irrelevant to the longitudinal reinforcement ratio;(3)The destruction characteristics of the UHPC test beam are nearly consistent with the destruction characteristics of the reinforced concrete beam.2?Based on the measured test data,the theoretical formula was deduced:(1)The cracking moment formula of the UHPC beam considering the plasticity of the tensile zone of the beam was established and compared with the experimental measured cracking moment;(2)Demonstrate that the stiffness calculation formula of “Specifications for Design of Concrete Structures” is not applicable to the calculation of UHPC beams,and it is recommended to use the stiffness calculation formula of “Technical Regulations of Reactive Powder Concrete Structures” for the calculation of UHPC beams;(3)Concrete stress distribution of UHPC beams in the compression zone is equivalent to the coefficients ? and ? of the rectangle,and considering the tensile stress contribution of the concrete in the tension zone,the flexural ultimate bearing capacity formula of UHPC suitable reinforced beam is established.The measured values of the experiment are consistent;(4)Using the flat section assumption to obtain the limit coefficient of the relative compression zone height of the UHPC beam,the flexural ultimate bearing capacity formula of the UHPC super-reinforced beam is obtained,and the limit reinforcement ratio of the longitudinal reinforcement of the UHPC beam is given Calculation formula..3?Using ABAQUS finite element software to model UHPC test beam,the effect of concrete and rib strength rating on UHPC test beam anti-bendperformance was studied.The analysis and calculations show that:(1)The calculation results of the finite element model are in good agreement with the measured values of the UHPC beam test;The height of the beam;(3)Increasing the strength level of the longitudinal reinforcement can improve the yield bending moment and ultimate bearing capacity of the UHPC concrete beam.