Research On Anomaly Diagnosis Of Roof Structure Based On Bayesian Method Under Temperature Variation

Structural health monitoring is becoming an increasingly important area in ensuring the safety of public buildings such as large span bridges and large building structures during construction and service.Structural anomaly diagnosis technique is the inverse process of structural design and structural verification,which aims to reflect the changes in structural material parameters,geometric characteristics,and abnormal loads during service by monitoring the changes in structural response.Considering environmental factors such as temperature in structural health monitoring progress has been a consensus.However,the uncertainty of monitoring data usually makes it difficult.In this paper,the uncertainty factor has been introduced into the anomaly diagnosis process,a Markov chain-Monta Carlo anomaly diagnosis method based on temperature-induced response has been proposed.First,a novel diagnosis index has been developed based on the temperature data and static strain response data collected by the SHM system,which can reflect the anomalies of the member itself,the neighboring members and boundary conditions,also include the uncertainties caused by temperature effects to a certain extent.Then,the Markov chain-Monta Carlo process is used to analyze the diagnosis index,and the posterior frequency distribution histogram of the actual diagnosis index is obtained.Finally,by analyzing the histogram of an unknown state and the initial state(baseline state)of the structure,the anomaly probability of the unknown condition is obtained,which can be used to diagnose structural anomaly such as structural members damage,external load changes,and changes in support boundary conditions.This method takes into account the uncertainty,of which the availability is evaluated by a laboratory truss structure test under a series of working conditions and is verified by a field monitoring data of a hanger roof structure and single-layer spherical mesh shell simulation experiments.The following conclusions were obtained:(1)There are obvious correlations between the stress-induced strain and the temperature measured by the sensors.However,there are also certain uncertainties.(2)In the laboratory truss structure test,the damage of member itself and the neighboring members can be diagnosed,and the deeper the damage,the greater the change in index.(3)Based on the field monitoring data of the hangar roof construction,the method is used to effectively diagnose the structural state changes that could not be directly observed from the time history curves of strain and temperature.(4)In the anomaly diagnosis of single-layer spherical mesh shell,better results are achieved in the diagnosis of member damage,external load variation and support failure,and the diagnosis of damage degree of the member is achieved by artificial neural network.