Reliability Of Construction State Of Continuous Rigid Frame Bridge Based On Support Vector Machine

The continuous rigid frame bridge is widely used in large span bridges because of its large stiffness and comfortable driving,It has been widely used in long-span bridges than the same span bridge.The bridge design develops in the direction of lightness and fineness,but the span and load of the bridge are constantly increasing,Security problem of the bridge is more prominent.the continuous rigid frame bridge constructed by adopting the cantilever casting method is subjected to the plurality of external loads during the construction process,The influence of structural resistance factors is not completely determined,There is a great change in the state of the bridge in the construction process.Because of the large discreteness of the structural analysis parameters,the reliability analysis method can better reflect the safety condition of the bridge,In this paper,reliability analysis method based on probability theory and mathematical statistics is used to study the reliability of cantilever construction of continuous rigid frame bridge.The following studies have been carried out:(1)By analyzing the theory of structural reliability,According to the<Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridge and Culverts>JTG D62-2004 and<Technical Specifiction for Construction of Highway Bridge and Culvert>JTG/T F5 0-2011 The requirements for the inspection of the construction process.The system failure mode of cantilever construction of continuous rigid frame bridge is determined.the bridge structure of the cantilever construction process is a static system,As long as there is a member or section of failure,There are two forms of destruction in the section of the concrete,which are crushed and cracked by concrete,The analysis of the reliability of the cantilever construction process system of continuous rigid frame bridge consists of two modes of concrete stress failure and tensile stress failure.(2)System reliability is a joint analysis of multiple functional functions,It is a problem that multiple limit state equations are divided into a system reliability domain and a failure domain,The basic theory of SVM classification algorithm is analyzed,the classification is a classification of a parameter sample with some same characteristic,Not specific response parameters of sample value influence,this feature determines that the support vector machine classification algorithm can simultaneously fit a plurality of limit state equations to solve the problem of classification surface of the system reliability domain and the failure domain,Using finite element analysis software MIDAS CIVIL to simulate the process of cantilever construction of Hongshui River Bridge in high speed,a training sample is provided for a classification surface of a support vector machine fitting structure reliable domain and a failure domain.(3)by analyzing the basic principle of the classification algorithm of the support vector machine,Presents a method of surface fitting classification,For linear inseparable problem,The support vector machine classification algorithm is to map the sample of the original parameter space to the high dimensional feature space,Make the problem a linear classification problem,The mapping method is determined by the parameter adjustment of the kernel function,By adjusting the parameters of kernel function,controlling the average relative deviation and the response value distribution condition of two types of support vector response values,Classification of surface optimization method(Sample migration and increasing local samples)to fit the training samples with high accuracy,a method for verifying the deviation between the fitting classification surface and the real classification surface by using the verification point response value is adopted,The Monte Carlo method is used to calculate the failure probability of the structure by sampling the classification surface function.This method is used to fit the classification surface of a dominant limit state equation,and it is proved that the method is effective and efficient.(4)The above method is used to analyze and evaluate the reliability of the cantilever construction process of the Hongshui River Bridge,Get in the distribution of construction load under the action of various factors,the reliability index of the construction process of the bridge is 3.719,Lower than the reliability index required in the operation phase of the bridge,The construction process structure is affected by many factors,the construction process is more risky than the operational phase,The proposed reliability calculation method can be used as a reference for reliability analysis of other structures.