Capacity Assessment of the Titus Tunnel Bridge Using Analytical and Numerical Techniques

Abstract

A great number of masonry arch bridges are still in service in Europe, the Middle East, and other parts of the world. Assessing the capacity of these historical structures is an important problem both for safety and preservation purposes. This paper addresses the assessment of the Titus Tunnel Bridge, a single-span, Roman stone arch pedestrian bridge (Common Era 70) located in Antakya, Turkey, using analytical and numerical techniques. The bridge is located in an active seismic zone and has survived several major earthquakes. Therefore, it is important to understand the Bridge’s subtle features that have helped the structure survive for the last two millennia. Furthermore, being a single-span semicircular stone arch, the bridge exemplifies the main construction blocks of several masonry bridges around the world. First, the analytical techniques, i.e., Heyman’s geometrical factor of safety and the mechanism method, are used to assess the capacity of the bridge under simple loading conditions and to validate the finite-element (FE) models. Then, discrete FE modeling with explicit time integration is used to investigate the arch behavior under both gravity and earthquake loading conditions. It is observed that the Titus Tunnel Bridge has a significant margin of safety against collapse, which also explains the approximately 2,000-year lifetime of the structure. The results are also used to provide estimates on the maximum expected ground motions in the region using a precarious rocks analogy.