Bearing Capacity Analysis Of Steel Trestle Under Complex Conditions Based On Reliability Theory

Steel trestle is usually a temporary structure built as transportation materials,equipment and personnel,which is widely used in various construction projects.Its design is based on the limit equilibrium safety factor method for checking and analysis.The safety factor method uses fixed values to check the design parameters and design conditions,which fails to reflect the variability and randomness of actual variables.However,in the actual use of the trestle process,due to the complex and changeable construction conditions,steel trestle after long-term repeated use,the bearing capacity of the bridge has declined,even lead to engineering accidents.The reliability analysis of steel trestle can apply different external loads,influencing parameters and other factors to the influence of structural safety by probability method.Reliability index has great significance in carrying capacity analysis of steel trestle.Taking a temporary steel trestle for construction as the engineering background,this thesis studies and analyzes the bearing capacity of steel trestle for construction in water by means of field monitoring and numerical simulation.The reliability analysis method is used to study the reliability index of the trestle structure under various complex working conditions.The bearing capacity of the steel trestle is checked under the condition of insufficient anchorage depth of the steel pipe pile,which provides a theoretical basis for similar projects and has certain practical application value.The main work is as follows :(1)Based on the quasi-static load test,the deformation of steel trestle was monitored on site.The monitoring results show that the stiffness and strength of each component of steel trestle meet the stability requirements.According to the reliability theory,the JC method is used to calculate and analyze the reliability index of the test data of steel pipe pile and bearing beam,and the reliability index meets the specification requirements.(2)The normal working state of steel trestle is analyzed by numerical simulation,and the overall stability of steel trestle is analyzed.The numerical simulation analysis of steel trestle under complex working conditions is carried out to obtain the maximum bending moment at the most unfavorable position of the trestle bearing beam,which provides data support for subsequent reliability index calculation.(3)Based on the reliability theory,the reliability index of the data obtained by numerical simulation under complex working conditions is calculated and analyzed.The MATLAB programming is used to calculate the reliability index of the bearing capacity of the trestle components under different working conditions.It is concluded that when the flow velocity is too large and the beam truck is overweight and unbalanced,the reliability index is lower than the minimum target reliability index required by the specification,and the other working conditions meet the specification requirements.The horizontal bearing characteristics of steel pipe piles under different anchorage depths are studied and analyzed,and the influence law of pile foundation anchorage depth on the overall horizontal displacement of the trestle is obtained.The reliability theory is used to calculate the minimum anchorage depth to meet the specification,which provides reference for steel trestle construction under similar geology.