Finite element analysis of bending performance of prestressed self-compacting recycled concrete beams

YU Fang; HU Min; YAO Dali; WU Fan

doi:10.7688/j.issn.1000-1646.2025.05.16

Abstract：[Objective]As the demand for resource recycling and sustainable development in the construction industry increases,the application of recycled aggregate in concrete structures has become a research hotspot.However,the mechanical properties of recycled aggregate differ from those of natural aggregate.The low tensile strength,elastic modulus,and high brittleness of recycled aggregate inevitably have a significant influence on the bending performance of prestressed self-compacting recycled concrete(PSRC)beams.To clarify the feasibility of employing recycled aggregate in PSRC beams,this study discussed and analyzed the bending performance differences between PSRC beams and prestressed normal concrete(PNC)beams.[Methods]This paper adopted the finite element analysis method for the study.Firstly,the finite element models of PSRC beams and PNC beams were built based on the ABAQUS software.Meanwhile,the correctness and reliability of the built models were verified by comparing the failure modes,load-deflection curves,and limit loads of the simulated specimens with those of the test specimens.Secondly,on the basis of model verification,a systematic comparison and analysis were conducted on the performance indicators such as cracking load,limit deflection,flexural bearing capacity,and tensile reinforcement strain of PSRC beams and PNC beams.Additionally,based on the maximum and average strain of the tensile reinforcement at the cracking point,the coefficient of uniformity of the tensile reinforcement was corrected,and a calculation formula for the maximum crack width of PSRC beams was established.The applicability and accuracy of the formula were verified.[Results]Under the same reinforcement ratio,the cracking load of PSRC beams is smaller than that of PNC beams,and the difference in crack resistance performance between the two types of concrete beams gradually decreases with the increasing reinforcement ratio.Under the reinforcement ratio between 0.10％and 2.24％,the limit deflection of PSRC beams is 4.04％-19.03％higher than that of PNC beams.Then,as the reinforcement ratio continues to increase,the limit deflection difference between the two types of concrete beams gradually decreases until it is basically zero,which means the influence of the material properties of concrete on the deformation capacity of the component gradually decreases with the rising reinforcement ratio.The flexural bearing capacity of PSRC beams and PNC beams differs by no more than 3％,indicating that the existence of recycled aggregate has little effect on the flexural bearing capacity.Under the action of the same load,when there is a crack in concrete,the strain curve of the tensile reinforcement of PSRC beams is slightly lower than that of PNC beams.Due to the earlier cracking of PSRC beams,the tensile stress transmitted by the tensile zone concrete is borne in advance by the longitudinal reinforcement at the crack,resulting in larger tensile reinforcement strain at the cracking point of PSRC beams than that of PNC beams.[Conclusion]This study proposed a new method for determining the maximum crack width of PSRC beams based on the strain simulation data at the cracking point to correct the coefficient of uniformity of the tensile reinforcement.The maximum crack width was calculated by adopting the proposed new calculation method and the formula in GB50010-2010.It is found that the calculated values of the proposed formula are in sound agreement with the measured values,and the predicted maximum crack width by the proposed formula is more accurate than that by the formula in GB50010-2010.This paper provides a reference basis for the revision of subsequent standards.