Unraveling the structural deterioration of Isfahan's Sio-Se-Pol Historical Bridge: A finite element analysis approach

The extent of damage to historic structures is influenced by several factors, including the magnitude and distribution of static and dynamic loads applied over time, as well as fluctuations in the stability level that lead to nonlinear behavior. In this study, the nonlinear behavior of the Sio-Se-Pol Bridge in Isfahan is investigated with respect to these factors. The complex behavior of building materials under different loading conditions poses a challenge for numerical modeling of historical structures. Tensile cracks in building materials can occur due to static and dynamic loading and lead to a reduction in cross-sectional stiffness. This phenomenon exacerbates the severity of existing cracks, stimulates the formation of new cracks and increases the structural deformation of the building. Therefore, it is crucial to use an advanced behavior model that is able to effectively simulate the occurrence and growth of tensile cracks. In this study, the damage-plasticity model based on plasticity theory was used to analyze stresses in brittle materials such as brick building materials. Insufficient knowledge about the material behavior and lack of information about the strength parameters made it necessary to perform various tests on the brick unit (brick and mortar) used in the bridge. According to the results of the non-linear analysis, the dimensions of the current foundation are considered sufficient for the stress distribution under the foundation, taking into account the bearing capacity ratio and the settlements in the transverse direction. The drop in the groundwater level does not appear to have a significant impact on the width of the bridge in terms of structural damage. The occurrence of longitudinal tension cracks with a uniform pattern over the entire length of the bridge can be attributed to changes in the load transfer system and the associated local effects.