مقایسه حالت های شکست در سطح و خارج از سطح از پل های قوس سنگی
Abstract
1- Introduction
2- Background on numerical analysis of masonry arch structures
3- Discrete element validation for masonry arches
4- Simulation of masonry arch bridge models
5- Discussion on spandrel wall behavior
6- Conclusions
References
Abstract
This research aims to provide a better understanding of the structural behavior of masonry arch bridges using advanced modeling strategies. Two main contributions are achieved in this article; first, triggering mechanisms for the out of plane failure of spandrel walls are established; second, the influence of soil backfill on the behavior and strength of the bridges is presented through a comprehensive parametric study. Here, masonry arch bridges are modeled using a discontinuum approach, composed of discrete blocks, including also a continuum mesh to replicate infill material, adopting a framework of discrete element modeling. The equations of motion for each block are solved by an explicit finite-difference method, using the commercial software 3DEC. The results of the preliminary analyses are compared with analytical solutions and limit state analysis for validation purposes. Different arch bridge models, representing common geometrical properties in the northwest Iberian Peninsula are analyzed. Transverse effects, damage patterns and collapse mechanisms are discussed under different types of loading. The analysis demonstrated the severe capacity reduction due to spandrel wall failures and the importance of soil backfill in results, only possible by taking advantage of the performed numerical modeling strategy.
Introduction
Masonry arch bridges constitute an important asset of the transportation infrastructure not only in Europe but also in northeastern United States [1]. Although, newer construction materials, such as steel or reinforced concrete, became more popular in the construction sector after the mid-20th century, stone and brick masonry bridges still continue to make a remarkable contribution to world’s infrastructure. For instance, masonry arch bridges constitute around 40% of the bridge stock in Europe [2]. In United States, there are 1700 masonry bridges, according to the 2013 National Bridge Inventory (NBI) [3]. Given that the majority of these bridges are older than 100 years [4], they may suffer from material deterioration, lack of maintenance, increased axle loads and high volume of traffic through the decades. Notwithstanding, a remarkable portion of masonry bridges still constitute the heritage of transportation system in many countries. Therefore, preserving their structural integrity has a critical importance due to their historical significance. On the other hand, it has been a challenge for engineers to analyze masonry arch bridges because there are no widely adopted structural analysis procedures, and true understanding of their complex behavior requires nonlinear analysis. Furthermore, there are numerous parameters affecting the strength, stiffness and overall collapse mechanism of masonry bridges such as: boundary conditions, backfill properties, span, rise and arch thickness among others. In this research, a vulnerable local failure mechanism, namely spandrel wall collapse, and global failure mode of arch barrel are investigated. In addition, a parametric study is performed on the backfill properties and the obtained results are compared with a simplified approach. The capacity and the transverse failure of spandrel walls are simulated by means of three-dimensional mixed discrete-continuum approach.