Key Technologies Of Health Monitoting Of A Half-Through Arch Bridge With Steel-Concrete Composite Bridge Deck System In Service

As an important transportation infrastructure, the structural safety, durability, serviceability during their service of bridges are directly related to national economic development and people’s life and property safety, so it widely receive attentions. In the1990s, half-through reinforced concrete arch bridges were heavily built due to their smaller height of the building, shorter bridge approach, fewer columns, light weight, simple construction, and aesthetic shape. However, due to the influence of the rapid growth of traffic, aging of the structure materials and other factors, a series of damage have appeared in the large number of half-through reinforced concrete arch bridges in-service. Moreover, the existence of damage will reduce the bearing capacity of the bridges, affect the working performance during their use, and even cause serious bridge collapse. Therefore, take a half-through arch bridge with steel-concrete composite bridge deck system in service as engineering background, some key technological problems involved in health monitoring in this dissertation studies. Its main contents and conclusions are as follows:(1) Based on structural finite element analysis theory, combined with the structure and mechanical characteristics of a half-through arch bridge with steel-concrete composite bridge deck system, static and dynamic finite element equations of this type of arch bridge are derived respectively when the geometric stiffness of boom system being considered and not. The geometric stiffness matrix and tension general formula of boom system are derived. Combined with the bridge construction process, the tension formulas of boom system in different stages of construction are deduced based on the control of displacements. Then the above finite element analysis theory of a half-through arch bridge with steel-concrete composite bridge deck system considering the geometric stiffness matrix of boom system is used to analyze the static and dynamic performance of a retrofitted half-through arch bridge in service, and analysis results close to practical engineering are obtained.(2) For a half-through arch bridge with steel-concrete composite bridge deck system in service, by regular inspection, the preliminary technical condition of the bridge is assessed. And these results can provide the basic data for the subsequent static and dynamic load test, finite element analysis, and finite element model updating of the bridge.(3) Combined with its regular inspection, the initial space finite element model of the half-through arch bridge with steel-concrete composite bridge deck system in service is established, which is based on the above finite element analysis theory of the half-through arch bridge considering the boom system geometric stiffness. Then the boom tensions at the various construction stages are calculated, the static performance of the bridge in the construction phase and the dynamic characteristics after the completion of the bridge are analyzed. The results of the static analysis show that section stresses during the construction phase meet the design requirements for the longitudinal and horizontal beams of the composite bridge deck system. The results of the dynamic analysis indicate that:vertical stiffness of the steel-concrete composite bridge deck is relatively small and the vertical stiffness of box-shape arch rib is relatively large; the overall anti-torsion rigidity of the half-through arch bridge is larger, and the box-shaped arch ribs followed. Comparison of the results of the dynamic analysis considering the geometric stiffness of boom system and not, shows that for the top five frequencies, the former increase4.11%～5.14%than the latter. This indicates that the geometric stiffness of boom system should be considered when the half-through arch bridge with steel-concrete composite bridge deck system is designed and analyzed.(4) For a bridge structural vibration with the unknown input, according to the random vibration theory, the power spectrum peak method based on ambient vibration is proposed to identify modal parameters. For the dynamic load test studies of the half-through arch bridge, the modal parameters of the arch bridge are identified by the power spectrum peak method based on ambient vibration. The modal parameter identification method, by which the modal parameters can be identified from less data, is simple, fast, reliable, and low-cost and can be applied to modal parameters identification of large-scale complex bridge structures.(5) For the half-through arch bridge with steel-concrete composite bridge deck system in service, comparison of the modal parameters identification results of dynamic test and modal analysis results of the initial space finite element model is found that the finite element model of the bridge need updating. Then a model updating method by modifying the design parameters based on optimization analysis is develop to achieve updating of space finite element model of the studied bridge through the optimization function of ANSYS. Correction parameters are selected with the sensitivity analysis and bridge engineering experience. The finite element model updating method based on the optimization analysis is simple and practical, which can be widely used for model updating and health monitoring of large-scale bridge structures.(6) For the half-through arch bridge with steel-concrete composite bridge deck system in service, the static load test and theoretical modeling analysis are implemented. Eight Load Cases are set up. to obtain the strain and deflection of control cross-sections of rib, vertical and horizontal steel beams for static load test. Using the updated finite element model of the bridge, the static analyses are conducted. A method combining the static analysis of the updated finite element model with static load test is raised to evaluate the working performance and actual mechanical conditions of the bridge. The results show that the overall stiffness of the bridge is larger and strength of each component meets the design requirements. The globe bridge structure in service has certain safety reserve capacity, and is in good working condition. Reliability of the above finite element model updating method based on the optimization analysis of ANSYS is also validated. The modified finite element model of the half-through arch bridge with steel-concrete composite bridge deck system in service can be used as a baseline finite element model, being applied to health monitoring, damage detection, the overall performance evaluation during its subsequent service.(7) The technical files of the half-through arch bridge with steel-concrete composite bridge deck system in service is set up by static and dynamic load test and finite element simulation, and baseline data provided for inspection and assessment of the health status during its subsequent service.