Monitoring Of Bending Deformation Of Bridge Deck Based On Strain Measurement

Bridge deformation is not only an important parameter of bridge health monitoring,but also one of the key parameters of safety assessment to the bridge.Previous research on bridge deformation mainly focused on its overall vertical bending deformation as well as the vertical bending deformation of beam structure,while in the bridge structure with a larger transverse span,the local position of bridge deck would also produce larger transverse bending deformation.At present,the bridge deformation identification based on strain measurement is mainly aimed at the overall vertical bending deformation of the bridge.However,because the bending deformation of the bridge deck is a description of the deformation of the bridge deck in two-dimensional plane,this method is not suitable for monitoring the bending deformation of the bridge deck.This thesis presented a novel two dimensional plate bending deformation monitoring theory and method based on the measured strain.The specific works of this thesis are as follows:1.A method based on Navier Solution for lateral bending deformation monitoring of simply supported rectangular plates with four edges is proposed.The deck on longitudinal & transverse beam system can be regarded as simply supported rectangular plates on four sides.The strains of simply supported rectangular plates on four sides are expressed in the form of double triangle of Navier Solution,and the undetermined parameters are determined by the measured strains.Based on the displacement-strain relationship of the theory of elastic thin plates,the displacement function of the entire rectangular plate is obtained by quadratic integration.Finally,the transformation from measured strains to the bending deformation of the bridge deck can be visually expressed by displacementstrain transfer matrix.2.The transverse bending deformation monitoring of unidirectional plate based on twodimensional strain function fitting is proposed.For unidirectional plates with transverse end constraints,assuming that the transverse strain is a polynomial function of transverse cubic and longitudinal first order,the undetermined parameters are determined.Based on the theory of elastic thin plates,the displacement functions of local transverse bending deformation of unidirectional plates with transverse end constraints can be obtained,and the displacement-strain transfer matrices are derived.3.The transverse bending deformation monitoring of bridge deck method based on strain interpolation surface fitting is proposed.In view of the situation where the strains in the whole deck cannot be expressed by a specific objective function,the discrete strains are extended to the strain interpolation surface of the whole deck by using bicubic spline interpolation,which is also a piecewise function in the deck plane.Finally,based on the theory of elastic thin plates,the displacement functions of local lateral bending deformation of bridge decks with various transverse end constraints can be obtained.4.In order to verify the effectiveness and practicability of the proposed monitoring methods,several groups of numerical simulations have been proceeded for various kinds of bridge deck bending deformation monitoring methods based on strain measurement,and a series of loading experiments were carried out for simply supported rectangular plates at both ends.From the results of numerical simulations and experiments,it can be seen that the proposed method has certain accuracy and can be used in the bridge deck bending deformation monitoring in practical engineering.