Theory Of Structure Identification And Performance Prediction Under Complex Stress State Using Area Distributed Sensing Technology

In recent decades,research of structural health monitoring technology has received preliminary application in all kinds of civil engineering structures.There are more than 300 super-large bridge installed on all kinds of high-priced health monitoring system.These health monitoring system for dealing with emergencies have played a positive role,but because there are many problems,the "health" monitoring still can't realize,such as,most of current sensing technology are 'point' sensing technology,the application to complex giant structures of civil structure has some limitations;The relation between massive monitoring data and structure performance is weak;the number of types and quantity of sensor is high,system structure is complex,huge amounts of data is difficult to effectively handle,and so on.Many researchers at home and abroad have developed a variety of structural damage identification and positioning method,but due to the large span bridge structure is complex,massive,high redundancy and the influence of environmental factors,the applications of these methods to the massive monitoring data of real bridge are difficult to ensure the effectiveness of the state of early warning and assessment.Therefore,in view of the above problem,this paper developed the area distributed sensing technology applied to the structure health monitoring of large civil engineering and the theory method.In this paper,the research contents and innovation points are as follows:(1)Deformation distribution identification of tied arch bridge(tie beam,arch rib)based on area distributed sensing technologyFor the deflection distribution identification of tie beam,the axle strain distributed is first determined,the bending strain is then separated from the measured strain with the help of a special sensor layout to estimate the Deformation distribution;For the Deformation distribution identification of arch rib,because the bending moment and axial force all contribute to the deflection of arch rib,the curvature caused by the bending strain and axial strain is used as a distributed load,imposed on the conjugated beam,the calculation of bending moment of conjugate beam is used to identify the vertical deformation distribution of arch rib.(2)Optimal layout of long-gauge sensors for deflection distribution identificationTo determine the optimal sensor layout scheme for accurate deflection identification of the tied arch bridge,the method of optimal layout of long-gauge fiber optic sensors is studied,in which the characteristic curve is first developed by using the bending macro-strain curve under multiple target load conditions,then optimal sensor layout scheme with different number of sensors are determined.A tied arch bridge is studied as an example to verify the effectiveness and robustness of the proposed method for static and dynamic deflection identification.(3)The calibration of influence lines based on field calibration testThe continuous beam is to be an example to demonstrate the calibration method.Based on the principle of force method,the formula of influence line of continuous beam is deduced,by using the derived influence line to simulate the structural response under the calibration test,the results are compared with the measured response,the calibration coefficient of each sensor for influence line can be got.Thus,the derived influence lines is calibrated to obtain the influence lines formula of real bridge.(4)A bridge Weigh-in-Motion method based on area distributed sensing technologyThe influence line formula is the basis of this method.The axle spacing and axle weight ratios are also determined from the strain measurements near the supports of bridges using the maximum strain difference method;The maximum strain is calibrated by eliminating the influence of axial space and axil weight ratios;The calibrated maximum strain under verification test is compared with the corresponding value under calibration test to identify the gross vehicle weights;Combined with the axle weight ratios,the axle weights can be obtained.The method of maximum strain value to identify vehicle weights has the robustness and ability to resist noise.(5)The macro strain flexibility theory based on complex mode indicator functions(CMIF)Compared with the displacement flexibility theory using the CMIF,the proposed macro strain flexibility theory method include the single value decomposition of strain frequency response function matrix and the identification of strain mode shapes;on the basis of identified strain mode shapes,the displacement mode shapes can be estimated by using the conjugated beam method;the calculation of enhance frequency response function and the identification of basic modal parameters.Finally,the macro strain flexibility matrix is determined by these macro strain modal parameters.(6)Structure performance prediction theory based on bridge rapid assessment methodBased on the proposed bridge rapid assessment method,the nominal calibration coefficient is obtained and is spread by the influence line theory;because there are difference between actual influence line and theoretical influence line,the performance degradation index is derived;Using a series of degradation index form the regular monitoring of bridge,the degradation model is established to predict structural performance.