Research On Optimal Design Method Of Seismic Reinforcement For Bridge Structure Avoiding Frequency Exclusion Zone

As the key node of transportation network,bridge engineering is the lifeline of urban social and economic development.Most of the bridge engineering in Our country is reinforced concrete(RC)structure,because of long-term service in complex natural environment and traffic environment,such structures often face serious durability problems,such as performance degradation caused by steel corrosion.In addition,China is an earthquake-prone country,every year due to the earthquake caused by bridge structural damage for the national security problems and economic losses.The damage identification of the existing damaged bridge structure and the reasonable reinforcement scheme are helpful to restore its service performance as soon as possible.Therefore,the damage identification and seismic reinforcement of the damaged bridge structure are of great significance.For accurate identification of bridge structure damage status and improve the seismic behavior of the bridge structure after reinforcement,this paper first puts forward the low-order modal information of structural damage identification based on the static and dynamic parameters of intelligent method and verified the accuracy and noise resistance,according to the structure of power after the fingerprint features to build a kind of evading frequency structure reinforcement design method of the area,An example is given to verify the proposed reinforcement design method.Finally,the corroded RC pier column model and the seismic damage RC pier column model were established respectively based on Open Sees platform.The structural damage parameter identification and seismic reinforcement optimization design simulation were carried out for the established damaged RC pier column model by using the above identity-reinforcement design method,and the seismic performance vulnerability analysis was conducted before and after reinforcement.The specific work and research results are as follows:(1)By studying and comparing the ability of each static-dynamic indicator of the structure to represent the actual damage situation,and the requirements of each indicator on the quality and quantity of data,combined with the engineering practice,the damage identification objective function of the combined static-dynamic parameter is established.It is expressed as the processing and combination of the static displacement,natural vibration frequency and vibration mode of the structure,and condensed into the algebraic difference between the theoretical model and the experimental data,so as to reflect the fitting degree of the numerical model and the actual mechanical properties of the structure.(2)With the damage degree of the structure section as the design variable,PSO(particle swarm optimization)algorithm is used to minimize the optimization of the above objective function,that is,the actual damage of the structure is reflected as the degradation of the size of the structure section.By setting multiple single damage and multiple damage conditions,the accuracy of the recognition effect is verified without noise,and the results show that the recognition effect is good.At the same time,the anti-noise performance of the proposed algorithm is verified by adding gaussian white noise to the structure modal information.(3)Considering the change of natural vibration frequency caused by structural stiffness degradation,when the natural vibration frequency of each order of the structure drops to a certain value,its seismic performance will be greatly reduced.In this paper,an optimization design method of structural seismic reinforcement based on dynamic RBF radial basis function proxy model is proposed.The structural reinforcement size is determined by taking specific frequency restricted zone as the constraint condition and strengthening economy as the objective function.(4)Vulnerability analysis was conducted on the model before and after reinforcement using Open Sees platform,and dynamic response of the model before and after reinforcement was compared.The results show that the reinforcement design method with frequency exclusion zone as the constraint has more effective and accurate theoretical support for the seismic reinforcement of structures,the reinforced structures have better seismic performance,and the performance of the specimens after reinforcement has been improved in different degrees in the four vulnerability indexes.