Research On Nonlinear Stability Of 3D Printing Arch Under Settlement Of Arch Foot

With the rapid development of China’s transportation and construction industry,under the influence of foundation conditions,external environment and service load,the existing arch bridge and arched building structure will appear different degrees of uneven settlement of arch foot,which will lead to the increase of additional internal force of arch and affect its original function.In serious cases,instability may occur,which will pose a serious threat to the national economy and personal safety.In order to explore the influence of uneven settlement of foundation on arch stability,this paper takes 3D printing arch as the research object with the help of 3D printing technology which is widely used in various research fields in recent years.By means of theoretical derivation,model test and numerical analysis,the following research is carried out systematically:（1）Theoretical derivation and solution of nonlinear equilibrium equation of arch under uneven settlement of arch foot.Starting from the geometric relationship of arc arch,according to the principle of virtual work,the nonlinear equilibrium equation of arch under the condition of uneven settlement of arch foot under the action of concentrated load of arch crown is derived.The distribution of arch bending moment,radial and axial displacement is obtained by solving the equation.The instability extreme point and nonlinear instability path are obtained by solving the implicit equation method.The influence of uneven settlement on the nonlinear stability of arch is analyzed The influence of instability behavior.（2）3D printing arch molding and experimental loading system development.ABS-M30 printing material is used as raw material for 3D printing arc test arch model,and 3D printer is used for specimen printing.In addition,a new loading device is designed,including the support system which can control the settlement of arch foot.This loading device can adjust the support to change the displacement form of the arch foot,such as the vertical displacement of the arch foot,and real-time collect the load displacement curve of the 3D printed arch through the data acquisition device to record the instability and balance path of the 3D printed arch during the whole loading process.（3）Experimental study on nonlinear stability of 3D printing arch under settlement of arch foot.The basic mechanical parameters of 3D printing arch material are obtained through the basic mechanical property test,and the NDI Optotrak 3D measurement system is used to measure the whole loading process of 3D printing arch in real time,and the equilibrium path of 3D printing arch under different arch foot settlement and geometric properties,as well as the upper and lower extreme points of instability are obtained.（4）Nonlinear numerical analysis of 3D printing arch under settlement of arch foot.Through the finite element analysis software ANSYS,the corresponding finite element model of each test condition is created,and the load displacement curve under each condition is obtained.At the same time,the test results and theoretical results are compared and analyzed.It is found that the theoretical,experimental and finite element analysis results are basically matched,which verifies the accuracy of the theoretical derivation results and the reliability of the test data and finite element analysis results In one step,the effects of settlement of arch foot,rise span ratio and slenderness ratio on the stability of 3D printing arch are analyzed by parameters.