ABSTRACT
The subject Kanmon Bridge is a suspension bridge that is 1,068 m in length (with spans of 178 + 712 + 178 m). Put into service in 1973, it was the first in Japan to utilize parallel wire cables as the main cables based on the prefabricated strand method.
Currently, after more than 40 years of service in the Kanmon Strait and sustaining deterioration and damage from coastal climate and sea conditions, greater traffic volume, and larger vehicles, the bridge is undergoing major renovation.
As shown in Figure 1, plans for the superstructure include continuous floor framing stringers for the center span and side spans, creating the first such suspension bridge structure in Japan. Also, BP-B bearings will be adopted, cables will be installed to provide constant bridge axial displacement control during earthquakes, vibration dampers will be added, and other reinforcement measures will be taken to limit damage to stiffening girders and other main members. Structure of combined cable-damper-slide bearing system. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig285_1.tif"/>
As shown in Photo 1, areas adjacent to a wind tongue are difficult to evaluate using a frame model; therefore, they were modeled as shown in Figure 2, using 3D shell elements. Also, the wind tongue, tower, and connection to the anchorage were modeled with fiber elements, and a kinematic hardening-type bilinear model was utilized with plasticization taken into account. 3D modeling. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig285_2.tif"/>
A result of calculation of wind tongue connection is shown in Figure 3. In the future, we believe it will be appropriate to conduct a detailed study of plasticized areas, for instance, using local FEM analysis. Wind Tongue Periphery (Tower Side). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/pho_1a.jpg"/> Result of cal. of stress-strain relationship. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig285_3.tif"/>
When level 2 earthquake motion is input perpendicular to the bridge axis in a side span that is a simple truss structure less than 200 m in span length, it is possible for damage to occur to stiffening girder top chords at girder end areas, as well as to lateral bracing, floor truss top chords, wind tongue systems, abutment horizontal bearings, etc.
