Research On Development And Application Of Layered Shell Model

Layered shell model is a powerful tool for efficient simulation of two-dimensional structural members,which has been rapidly developed in recent years and widely applied in engineering practice.However,there is little research on layered shell model under complex stress state,which can not solve its mechanical response accurately,thus restricting the further application of layered shell model in complex structure.Therefore,through the secondary development of finite element program MSC.MARC,this paper establishes a new type of layered shell model combining multi-field related technologies,and applies the unit to machine learning optimization,new material research,out-of-plane punching simulation,crack width calculation and other fields.The research results are as follows:(1)The development of layered shell model is completed based on MARC.Based on the basic assumptions of the full-scale fixed crack model,the MARC software is redeveloped.By defining the non-linear relationship between in-plane and out-of-plane of the material,a general layered shell model calculation program is obtained.(2)Parameter optimization of reinforced concrete shear wall structure is realized based on layered shell model.Based on the optimization of machine learning algorithm,the parameter analysis of constitutive parameters is realized,the optimization strategy for hysteresis curve is put forward,and the parameter recommendation for finite element analysis of reinforced concrete shear wall is put forward,thus a new high-precision,efficient and universal calculation model of reinforced concrete shear wall is formed.(3)New material UHPC layered shell model is developed based on the layered shell model.A two-dimensional constitutive model for fixed cracks of UHPC is proposed,and66 compressed dog bones and 36 tensioned prism specimens are tested and studied.Relevant parameters in the constitutive model are calibrated and the model is developed in MARC software.Five UHPC shear wall specimens are simulated to verify the accuracy of the UHPC layered shell model.(4)The out-of-plane punching effect of reinforced concrete slab is simulated based on the layered shell model.A three-fold line model is proposed for out-of-plane analysis of concrete slabs.The out-of-plane mechanical behavior of concrete is simulated.The whole process from bending deformation to punching failure of out-of-plane concrete slabs can be successfully simulated.In addition,the database of punching tests was established and the key parameters of the three-fold model were calibrated.(5)The crack width is calculated based on the layered shell model.The calculation process of crack width using layered shell model is given,which closely connects the concept of strain in finite element analysis with the concept of crack width in engineering design.Finally,the cracking analysis of a simple composite beam concrete slab subjected to negative bending moment is taken as an example to verify and discuss important issues such as grid correlation,coping strategies for numerical convergence difficulties caused by large softening modulus,and decisive role of average crack spacing.The layered shell model developed in this paper can carry out comprehensive analysis on the whole process of various structures under stress,providing reference and basis for the design of complex structures.