ABSTRACT
An analysis and visual inspection is presented of the bridge over the “Quebrada de Tambura” in the Imbabura Province of Ecuador. This study emphasizes the visual inspection of the bridge, the elements taken into consideration for the assessment, and the relevant failure modes that can be identified throughout the process, leading to a recommendation for maintenance.
During the visual analysis of a bridge, it was possible to identify structural deficiencies; these problems have been compared with the results of an analysis performed in CSi Bridge. The study reveals that the observed cracking is related with the insufficient capacity of the bridge.
The capacity of the beams was calculated according to the original design drawings. Two load scenarios were modeled: Scenario I for the bridge subjected to load combination Strength I from AASTHO LRFD (2012) and Scenario II, which studies the influence of settlement of different values.
Comparing the results from CSi Bridge to the flexural resistance according to AASHTO LRFD for Scenario I, showed an insufficient flexural capacity, some sections undergo bending moments of 2% or 15% higher than their flexural capacity.
The dry river allowed the accessibility under the bridge for a visual inspection. At a pile scour that induced material loss and exposure of the foundation was observed. For these reason, it was assumed that the pile has settled, which led to the observed shear cracks. The analysis based on scenario II, showed that besides finding again an insufficient flexural capacity, also the shear resistance of the beams becomes insufficient starting at a settlement of 5 cm.
The analysis in CSi Bridge shows that the cracks in the beams and slab can be contributed to the settlement. The moment capacity at some sections was not sufficient, and this understrength could have caused some of the cracks observed during the visual inspection. Pile C Scour. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig229_1.jpg"/>
The settlement modeled in CSi Bridge relates the shear cracks to the cracks observed during the visual inspection. For a settlement of 5 cm and more the shear capacity of the beam is exceeded.
For rehabilitation of the damaged structure, it was proposed to apply fibers with an open jacket as a method of anchorage. FRP systems have been shown to increase the shear strength of existing concrete beams and columns by wrapping or partially wrapping the members.
To mitigate the effect of scour, underpinning of pile C is recommended.
