چكيده لاتين
This thesis investigates the structural behaviour of Persian brick arch bridges under various scour conditions. For the arch span cross-section shapes, semi-circular, four-centred, and pointed arches have been employed. Each of these arches has been evaluated in three types: drop, ordinary, and raised. The different scour scenarios studied for a single pier include the central and side piers, and for two piers, the two central piers as well as one side pier and one central pier. Those scenarios exhibiting the most and least favourable performance under uniform line and surface loads have been selected for further analysis under gravity loading for different ratios of geometric parameters, including: pier thickNess to arch span length at values of 0.10, 0.60, and 0.80; bridge width to arch span length at 0.75, 1, and 1.25; pier height to arch span length at 0.75, 1, and 1.25; and deck thickNess to arch span length at 0.25, 0.33, and 0.5, as well as settlement and seismic loading.
The studied samples have been analysed under four types of loading: uniform distributed load, line load at the mid-span with scoured piers, pier settlement, and seismic loading. Nonlinear analyses were conducted using the finite element software ANSYS, with the Willam-Warnke failure criterion employed to simulate the behaviour of brick materials.
The results of the uniform surface loading indicate that, in most scour conditions involving a single central pier, the load-carrying capacity is greater than that of a bridge with scour at a single side pier. Moreover, the two-pier scour condition shows weaker performance compared to a single-pier scour. Under line loading at the apex of the arch span, no significant differences were observed in any scour models. Regarding uniform surface loading, structures featuring drop four-centred arches at the bridge span demonstrate a significantly higher load capacity compared to semi-circular and pointed arches. For line loading at the apex with scouring of the central pier(s), the raised pointed arch exhibits the highest load-carrying capacity, while drop four-centred and semi-circular arches have the lowest load-bearing capacities.
Regarding pier settlement, settlement of a single side pier yielded better performance than other conditions, whereas settlement of a central pier resulted in the poorest outcome. Additionally, seismic performance analysis revealed that semi-circular and four-centred arches possess greater earthquake resistance compared to pointed arches. Overall, in bridges with symmetric geometry and pier scour, structural behaviour was satisfactory across all loading conditions.
