Reliability Analysis On Structural System Of Underground Silo Based On Response Surface Method

The underground grain storage can realize the constant temperature inside the warehouse and it overcomes the shortcoming of the high temperature in the aboveground granary in the summer,which can lead to the grain mildew and insect pests,effectively guarantee the quality of food.The cylindrical shell structure has the advantages of uniform stress distribution to the various parts of the structure and the effective use of the strength of the structural material.The large diameter reinforced concrete underground silo is a new type of underground granary.Its good mechanical and structural properties solve the dependence of the traditional underground granary on the terrain.Like other underground structures,there are a lot of uncertainties in the process of investigation,design,construction and operation of large diameter reinforced concrete underground silo.The fixed value analysis only considers the size of each parameter,and fails to take into account the mathematical statistical characteristics of many parameters,such as mean value and coefficient of variation,which can not accurately reflect the safety performance of the structure.This paper based on the theory of structural reliability,through the response surface method of ANSYS probability design,the reliability analysis is carried out under different control conditions for the three components of productive test storehouse of the large diameter reinforced concrete underground silo,which includes roof beam plate,silo wall and inverted conical bottom,and the system of large diameter reinforced concrete underground silo structure reliability is calculated.The specific research contents are as follows:(1)By monitoring the internal force of steel bars of the bottom and the silo wall of the large diameter reinforced concrete silo in the construction of the underground silo,and get the change rules of the measured value of the internal force of the reinforced concrete.Monitoring the internal force of reinforced concrete to provide the experimental basis for the reliability analysis of the large diameter reinforced concrete underground silo.(2)Based on the ABAQUS finite element program to carry out the monitoring test,the numerical simulation of large diameter reinforced concrete underground silo is carried out.Based upon the theory of soil& structure dynamic interaction,establish the overall three-dimensional calculation model of large diameter reinforced concrete underground silo and its surrounding soil interaction,the interaction between soil and structure were simulated with the contact unit,considering contact nonlinearity of soil and the silo and material nonlinearity of soil,analysis of the stress and displacement variation of underground silo in backfill construction process.To guide the actual stress state of underground silo in the process of reliability calculation.(3)Based on the concrete Hsich-Ting-Chen four parameter strength criterion,the performance function of the roof beam plate,silo wall and inverted conical bottom of the large diameter reinforced concrete underground grain silo are established,and according to the standard,the performance function of the radial deformation of the silo wall,the deflection of the roof beam plate and the deformation of the inverted conical bottom are established.By analysing the project cases,using the response surface method of probability design module of ANSYS to calculate the reliability of each component under various control conditions.The results show that the failure probability of each component under the condition of concrete strength is small,and the failure probability of each component under the condition of deformation control is relatively large,however,it is still in line with the requirements of the unified standard for reliability design of building structures.(4)The performance function of each component will be established under the different conditions,through the equivalent extreme value event theory,performance function establishment of series system of underground large diameter reinforced concrete silo structure,and the response surface method of ANSYS finite element program is used to calculate the reliability of underground silo structure system.The failure probability of large diameter reinforced concrete silo structure is larger than that of single component.Based on the sensitivity analysis of the reliability of the large diameter reinforced concrete underground silo structure system,the parameters which have great influence on the reliability of the underground silo structure system are obtained.