| In recent years,the long-span suspension bridge is applied more and more widely in China.However,with the increase of bridge service life,more and more bridge structures have been damaged and local damage to varying degrees,which seriously affects their normal use and safety.Therefore,it has become an important direction for many scholars to ensure the safe operation of bridge structure by health monitoring and state assessment of bridge structure through appropriate ways.However,from the current situation,health monitoring and safety assessment of long-span suspension bridges at home and abroad is still in the ascendant.Therefore,in order to ensure the safe operation of the large bridge structure and grasp the safe state of the bridge in real time,it has become the urgent task to study the effective bridge health monitoring system and the state evaluation method.Based on the above situation,the study is based on the Lancang River Bridge with a single span of 380 meters in Yunnan.The main contents and conclusions are as follows:(1)According to the positioning measurement principle of the Beidou navigation system and the existing monitoring techniques and means,the Beidou navigation and positioning technology is applied to the study of the actual bridge deformation monitoring.The research results show that Beidou navigation and positioning technology is feasible for deformation monitoring of suspension bridges,with high accuracy and low cost.The research provides an economic and effective monitoring means for suspension bridge in service condition monitoring and safety assessment.(2)A method of obtaining full bridge displacement and internal force based on finite point displacement data is presented,and its feasibility is verified by support engineering.The results show that the method is reasonable and feasible,and the accuracy of the inversion results is higher when the measurement points are increased.The accuracy of the load inversion can reach 95.8% at the 32 measuring points,which is20.5% higher than the accuracy 75.3% of the 6 points.(3)A method for retrieving full bridge state based on monitoring data of key section displacement is developed for long-span suspension bridges.Relying on the project of the Lancang River Bridge,on the basis of obtaining the key section displacement,by loading the equivalent node load of the main beam monitoring displacement to the finite element model,the internal force and the change of the key components of the suspension bridge,such as stiffening beam,hanger,main cable andso on,are obtained,and the whole bridge shape is realized.State analysis.(4)A safety assessment method based on displacement and critical structure envelope is developed for long-span suspension bridges.Through the displacement monitoring value of the Lancang River Bridge and the stress values obtained through displacement parameters,the safety evaluation is carried out by displacement and stress envelope method.The evaluation results show that in the selected time period,the corresponding displacement correction coefficients and displacement values of 3#,4#,5# and 6# are all within the given range of displacement envelope.At the same time,the stress of stiffening beam obtained from displacement parameters is also in the allowable stress range,and the bridge is in a safe operation state. |
