Reliability Analysis Of Movable Scaffolding System Structure Based On PC-Kriging Surrogate Model

The movable scaffolding system(MSS)is a large-scale construction machine with its own template.It can be on-site pouring concrete beams when supported by the pile or pier caps and moved by itself.It is widely used in on-site pouring construction of medium and small span and box girder bridges.The structure of the movable scaffolding system is complex.With the change of the span and width of the construction,there are more demand for the structural strength,rigidity and stabilit,and various safety accidents occur in the quality and safety accidents during the construction of the movable scaffolding.The assessment of its safety is particularly important.At present,most of the analysis of movable scaffolding is deterministic finite element simulation.The open literature of reliability research in the construction process of movable scaffolding has not been seen.This paper takes the movable scaffolding of Tongming Sea Bridge as the engineering background.The force analysis,load test and reliability calculation analysis of the modified movable scaffolding structure were studied,and the following main work was completed:(1)Using the finite-element method ANSYS to model and analyze the overall structure and the brackets of the movable scaffolding under the first-span pouring condition,compare the simulation calculation data with the measured data of the load test,and evaluate the effects of the modified movable scaffolding.The results show that the modified movable scaffolding has good transformation effect,and the strength and stiffness meet the design requirements,which is basically consistent with the theoretical calculation results.The structure is still in a safe state and the security reserves is small.(2)A reliability calculation method based on PC-Kriging surrogate model is proposed.Using the good lattice point sampling method,the PC-Kriging surrogate model is introduced to construct the response surface equation,and the reliability index is calculated by the MC method.The points with larger influence are added to the initial sample to update the modified response surface model to establish the optimal PC-Kriging surrogate model and calculates the structural reliability index.Numerical examples verify the accuracy and effectiveness of the proposed method.(3)Applying the reliability calculation method based on PC-Kriging surrogate model to the reliability calculation of the movable scaffolding,respectively calculating the normal use limit state reliability index of the deflection of the main beam and the lateral displacement under the wind load,and the reliability index of the bearing capacity limit state under the two load combinations.The results show that the movable scaffolding meets the requirements of normal use;under the bearing capacity limit state,it has high reliability index and good safety performance.