Analysis Of Bending Bearing Capacity Of Existing Reinforced Concrete Hollow Slab Beam

The reinforced concrete hollow slab bridge is one of the structural forms extensively applied in China's medium and small span bridges.With the constant improvement of road traffic capacity and service level,a higher requirement has been proposed to the performances of in-service bridges.Influenced by the external lots of adverse factors for a long time,the in-service bridge suffers increasing damages,continuously-deepening degree of damage,gradual degradation of structural performance.The above phenomena become the "bottlenecks" for the operation capability and safety of the road bridges.Therefore,the study on the flexural capacity analysis of the existing reinforced concrete beam is more and more important.This paper is based on the single beam two-point symmetrically-loading destruction test of the 8m-span reinforced concrete hollow slab beam serving for a certain expressway 20 years.The writer carries out the detection assessment of the damage status,geometric shape and material condition as well as the limit flexural loading test to the test beam.Based on the basic theories and materials of the Abaqus concrete damage plasticity(CDP)model,a CDP model of test beam is established in this paper.The CDP model is applied to simulate the generation and development of the direct tension cracking as well as the compression destruction process of the test beam.Based on the basic theory of the extended finite element method and the basic expansion theory of the XFEM(extended finite element method)cracks in Abaqus,a concrete crack extension model for the test beam is established to simulate the crack generation and extension.Through the calculation of Abaqus's concrete damage plasticity(CDP)model,and combined with the simulated results of the test and model,the writer makes test and theoretical analysis on the deflection,concrete strain,steel strain,destruction process and ultimate bearing capacity of the test beam to obtain the changing conditions of the normal ultimate bearing capacity and anti-bending ultimate bearing capacity of the test beam.Through the calculation for the tension and compression damages of the CDP model,the writer analyzes the generation and development trend of the test beam's damage cracks as well as the concrete compression destruction process at the compressed area of the top beam to obtain the tension and compression damage results of the CDP model,capable of indirectly reflecting the feasibility of the results of the above test beam.Through the extension model for the reinforced concrete beam crack via Abaqus's XFEM(extended finite element method),and based on the actual situation of the crack,multiple strips of cracks are prefabricated to simulate the stress development situation of the cracks,so as to obtain the feasibility to the expansion simulation of the reinforced concrete beam crack via the extension model for the XFEM reinforced concrete beam crack.Thus it can provide numerical simulation forecasting for the expansion situation of the cracks and ruptures in engineering structures.