Static analyses of bridge structures are currently performed using the finite element method (FEM). Depending on the geometry of the structure and the technically required accuracy of calculations, different levels of discretization of these structures are used in their design. In the design process, beam grillage models (denoted e1, p2), shell models (denoted e2, p2) or shell-beam models (denoted e1+ e2, p3) are often used. Solid models (denoted e3+ p3) are mostly used in advanced analyses, having frequently a scientific character. It is shown that there is an impact of the applied types of the numerical model (i.e., degree of complexity, degree of discretization, accuracy of the model) of the road bridge on the calculated values of bending moments and displacements, which indirectly affects the global safety coefficient of the designed bridge structure. The main purpose of the calculations is to examine the discrepancies of analyzed internal forces and displacements depending of the type of numerical model used. The calculated values are referred to the results taken from the field tests of the existing bridge denoted MS 03, which is a continuous beam structure with the three spans 37:50 + 46:75 + 37:50 m made of prestressed concrete and with variable beam depth. On the basis of numerical simulations, the paper provides author’s recommendations for computer modeling of similar bridges.

The level of degradation of reinforced concrete bridges was evaluated based on the in-situ measurements performed on five reinforced concrete bridges under service located in the Czech Republic. The combined effect of carbonation and chlorides with respect to the corrosion of steel reinforcement, namely the pH and the amount of water-soluble chlorides, were evaluated on drilled core samples of concrete. Based on these parameters, the ratio between the concentrations of Cl– and OH, which indicates the ability of concrete to protect reinforcement, was calculated. All the data were statistically summarized and the relationships among them were provided. The main goal of this study is to evaluate the non-proportional effect of the amount of chlorides per mass of concrete on the risk of corrosion initiation and to localize the “critical” locations in the bridges that are the most affected by the degradation effects.

The analysis was focused on three post-tensioned slab bridges, constructed in 1950s. Two of them function normally and will probably achieve the life span of 100 years required by the relevant regulations. The third one will likely be demolished soon and replaced with a new reinforced concrete frame bridge. To its degradation contributed the faulty diagnosis of its technical condition during its periodic technical inspections. The introduction briefly characterises the development of the prestressed structure theories reviewing papers on concrete rheology and monographs looking into prestressing. The paper is based on the existing fragments of the technical design documents concerning the bridges in question. The bridges were designed by Polish civil engineers.

The study presents the finite element (FE) model update of the existing simple-spans steelconcrete composite bridge structure using a particle swarm optimisation (PSO) and genetic algorithm (GA) approaches. The Wireless Structural Testing System (STS-WiFi) of Bridge Diagnostic, Inc. from the USA, implemented various types of sensors including: LVDT displacement sensors, intelligent strain transducers, and accelerometers that the static and dynamic historical behaviors of the bridge structure have been recorded in the field testing. One part of all field data sets has been used to calibrate the cross-sectional stiffness properties of steel girders and material of steel beams and concrete deck in the structural members including 16 master and slave variables, and that the PSO and GA optimisation methods in the MATLAB software have been developed with the new innovative tools to interface with the analytical results of the FE model in the ANSYS APDL software automatically. The vibration analysis from the dynamic responses of the structure have been conducted to extract four natural frequencies from experimental data that have been compared with the numerical natural frequencies in the FE model of the bridge through the minimum objective function of percent error to be less than 10%. In order to identify the experimental mode shapes of the structure more accurately and reliably, the discrete-time state-space model using the subspace method (N4SID) and fast Fourier transform (FFT) in MATLAB software have been applied to determine the experimental natural frequencies in which were compared with the computed natural frequencies. The main goal of the innovative approach is to determine the representative FE model of the actual bridge in which it is applied to various truck load
configurations according to bridge design codes and standards. The improved methods in this document have been successfully applied to the Vietnamese steel-concrete composite bridge in which the load rating factors (RF) of the AASHTO design standards have been calculated to predict load limits, so the final updated FE model of the existing bridge is well rated with all RF values greater than 1.0. The presented approaches show great performance and the potential to implement them in industrial conditions.