چكيده لاتين
Persian multi-span masonry arch bridges play a significant role in traditional infrastructure and construction, having been built during various historical periods. These bridges, depending on their usage, have backfill with different dimensions. The backfill enhance the load distribution on the structure, thereby increasing the load-bearing capacity of these bridges. Despite the rich history of brick arch bridges in Iran, limited studies have been conducted on their structural behavior under various loading conditions. This research aims to address this scientific gap by identifying and analyzing these impacts.
This thesis investigates the load-bearing capacity of Persian multi-span brick arch bridges and the effect of backfill on them. The bridges are examined with three types of arches: semi-circular, four-centered, and pointed arches, with the four-centered and pointed arches further divided into three categories: drop, ordinary, and raised. They are analyzed under vertical loading, support settlement, and seismic load using nonlinear analysis through the finite element software ANSYS.
The geometric parameters studied include the ratio of the middle pier width to the arch span (0.4, 0.6, and 0.8), the ratio of the side piers width to the middle pier width (0.5, 0.75, and 1), the ratio of the bridge width to the arch span length (0.75, 1, and 1.25), the ratio of backfill height from the arch crown to the arch span length (0.2, 0.3, and 0.4), and the ratio of the soil backfill height from the arch crown to the brick spandrel wall height (0, 0.25, and 0.5), for bridges with semi-circular arches under vertical load. Also, the ratio of the bridge pier width to the arch span (0.4, 0.6, and 0.8) and the ratio of soil backfill height from the arch crown to the arch span length (0.2, 0.3, and 0.4) are studied for four-centered and pointed arch bridges.
Vertical loading includes uniform loads on the bridge surface, linear loads at middle span of the central arch, and linear loads at middle span of one of the central pier. Support settlement includes settlement at one of the side pier and settlement at one of the central pier.
In this study, maximum load-bearing capacity for the mentioned loadings, crack locations under gravitational loading and support settlement, as well as optimal geometric parameters in different scenarios have been determined. The results indicate that backfill has a significant impact on the load-bearing capacity of the studied bridges. Furthermore, backfill had a better effect under linear loading compared to uniform loading.
The findings from this research can lead to optimal design for brick arch bridges against specified loadings. Additionally, understanding crack locations under various loading conditions can provide useful insights for strengthening and maintaining these structures.
