Study On PD-FEM Model Of Concrete Structure Failure Behavior

Since the advent of concrete materials,due to its abundant raw materials,it has good plasticity and pourability,high compressive strength,durability and fire resistance,etc.,and has been widely used in various fields of civil engineering,water conservancy and protection engineering.Become an important building material.However,concrete materials also have their own shortcomings.Under the effect of internal and external loads,the initiation,expansion,and convergence of cracks can easily form,eventually forming macro-cracks,and even causing structural damage.Therefore,the numerical simulation and experimental research of crack propagation of concrete materials have attracted great attention from academia and engineering.In many scientific and engineering fields,related numerical methods based on partial differential equations,such as the finite element method,have been widely used,but there are discontinuities when it comes to discontinuities such as crack initiation and propagation.The singularity of the spatial derivative of the variable does not exist.At this time,the fracture initiation location and propagation direction must be judged by the fracture criterion.After the crack has expanded,the mesh must be re-divided,and the calculation results are grid-dependent.In recent years,PD(Peridynamics)is a numerical method based on the idea of non-local integration.It solves the singularity of traditional continuum mechanics in dealing with discontinuous problems and has significant advantages in simulating crack initiation and propagation.It has gradually become a research hotspot in computational mechanics,engineering simulation and related fields.However,as a particle-like method,Peridynamics has low computational efficiency.In order to combine the advantages of Peridynamics(PD)in dealing with failure problems and efficient computational efficiency of finite element method(FEM),a hybrid model of Peridynamics and finite element method is proposed.,the research object is divided into Peridynamic subdomains and finite element subdomains,in which the improved prototype microelastic brittle(PMB)peridynamic model is utilized for the Peridynamics subdomain and the eight-node isoparametric element model is used for the finite element subdomain.and the truss element was used to connect the peridynamics subregions and finite element subregions.An implicit analysis method for Peridynamics and finite element hybrid modeling is proposed,which realizes the problem of dealing with discontinuities in the FEM framework.In this paper,the four node hybrid model and the eight node hybrid model are used to analyze the linear elasticity of the cantilever beam.The influence of the size of the overlapping area,the contact range and the material points size on the accuracy of the hybrid model is studied.Through comparative analysis,the eight-node hybrid model is more accurate than the four-node hybrid model.Secondly,four hybrid models are used to simulate the failure process of single crack concrete slab and multi crack concrete slab with different dip angles,and the crack propagation path and the final failure form are obtained,which verifies the effectiveness of the four hybrid models in dealing with crack propagation and failure.Through the proposed hybrid models,the influence of stirrups on the concrete is considered,and the critical stretch of the concrete material is modified to describe the initiation time of the peridynamic model of the concrete and the tension and compression of the concrete.Considering the homogeneous interaction and heterogeneous interaction,PD modeling under reinforced concrete frame under monotonic static loading is realized.The failure process of the frame under the two hybrid models and the base shear-vertex displacement curve were obtained in turn,and good results were obtained,which provided a new idea for the analysis of engineering structure failure.