Aiko Furukawa 교수

On April 25, 2015, a Mw 7.8 earthquake struck the Gorkha district of Kathmandu, Nepal. In Patan, vibrational characteristics of a 300-year-old two-story masonry building near Patan Durbar Square had been measured prior the Gorkha earthquake. In the inspection of the building after the Gorkha earthquake, several new cracks were found. The vibrational characteristics of the building were measured again, and it was found that the natural frequencies after the earthquake were smaller than those befo

We propose a dynamic analysismethod – a refined version of the DEM- that can simulate three-dimensional elastic, failure and collapse behaviors of structures. A structure is modeled as an assembly of rigid elements. Interaction between elements is modeled using multiple springs and multiple dashpots attached to surfaces of the elements. The elements are assumed to be rigid, but the method allows the simulation of structural deformation by permitting penetration between elements. There are two ty

In the maintenance of cable structures, such as cable-stayed bridges and extra-dosed bridges, it is necessary to estimate the tension acting on the cables. The safety of a cable is confirmed by checking whether the tension acting on the cable is within the allowable value. In current Japanese practice, the tension of a cable is estimated using the vibration method or the higher-order vibration method, which considers the natural frequencies of the cable. However, in recent years, the aerodynamic

The process of failure propagation of masonry buildings during earthquakes is simulated using a refined version of the distinct element method that simulates three-dimensional elastic, failure, and collapse behaviors of structures. Models with a flat roof and models with a vault roof are considered, and their failure propagation mechanisms are examined. The influence of the direction of the input ground motion on failure propagation is also investigated. Moreover, the effectiveness of three rein

Stomatal and epidermal cell frequencies and leaf area were measured in leaves of Quercus myrsinaefolia grown in the field under different relative photon flux density (PFD), which was the ratio of integrated PFD at the leaf surface to that at an open site. Leaf area showed a linear relationship with the relative PFD. Stomatal and epidermal cell frequencies increased with increasing relative PFD. Numbers of stomata and epidermal cells per leaf, and stomatal index (ratio of stomatal number to epid

Masonry structure is one of the most commonly used building types in developing countries due to its inexpensiveness and material availability. While masonry structure is intrinsically strong in resisting gravitational force, it is relatively weak in resisting lateral forces such as an earthquake. Therefore, reinforcement for masonry structures in earthquake-prone areas is necessary. This paper introduced an interlocking brick as one of the promising reinforcement methods for masonry structure a

Nielsen-Lohse bridges are tied-arch bridges, in which braced cables cross each other and are connected by intersection clamps. In the maintenance of Nielsen-Lohse bridges, cable tension has to be estimated for safety evaluation. In the current practice for cable tension estimation, the intersection clamps are removed, a vibration-based cable tension estimation method for single cables is applied to each cable, and the intersection clamps are then reinstalled. However, the removal and reinstallat

In the maintenance of cable structures, such as cable-stayed bridges, it is necessary to estimate the tension acting on the cables. In current Japanese practice, the cable tension is estimated from the cable’s natural frequency using vibration-based methods. However, in recent years, dampers have been installed onto the cables to suppress aerodynamic vibrations. Because the damper changes the cable’s natural frequencies, the methods used for cables without dampers are not appropriate for cables

In the maintenance of cable structures, such as cable-stayed bridges, cable safety is assessed based on the cable tension. In Japan, the cable tension is generally estimated from the cable’s natural frequencies using the higher-order vibration method. In recent years, dampers have been installed onto cables to suppress aerodynamic vibrations. Because the damper changes the cable’s natural frequencies, the damper is removed to measure the natural frequencies and estimate the cable tension without