Papers by Masamichi Saito
A 1986 survey of a large number of the approximately 50,000 steel railroad bridges in Japan were ... more A 1986 survey of a large number of the approximately 50,000 steel railroad bridges in Japan were found to be in need of attention, if not replacement. Japan's Railway Technical Research Institute has investigated the installation of concrete decks on steel girder railroad bridges as an alternative to bridge replacement. Combining steel girders with a concrete deck should strengthen the bridges sufficiently to avoid the time and expense involved in bridge replacement. Technical issues investigated include stress reduction; higher deadload; deck installation; and girder-deck connection. Tables outline deck installation methods, strengths of vertical and horizontal fasteners, and the results of loading tests to determine shear forces in filler mortar between deck and girder.
Quarterly Report of RTRI, 2020
This study aims to reveal the characteristics of and factors influencing uplift forces acting on ... more This study aims to reveal the characteristics of and factors influencing uplift forces acting on bridge bearings during earthquakes. Firstly, three different analysis models were compared through seismic response analyses in order to select a suitable model for parametric analysis. Secondly, factors influencing the uplift force were investigated by examining the seismic response analyses of six different bridge models of normal Japanese steel railway bridges. Finally, a nonlinear hysteresis model of a bridge bearing was proposed and the influence of using this model was investigated. As a result, it was confirmed that the response displacement does not exceed the limit displacement even during large-scale earthquakes.
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), 2012
Quarterly Report of RTRI, 2014
Concrete filled steel tube (CFT) members have been applied to the columns of rigid frame structur... more Concrete filled steel tube (CFT) members have been applied to the columns of rigid frame structures. However, the failure mode, the bending capacity and deformation performance of CFT members with small shear-span ratio are not clear because there have been few studies on them. In this study, cyclic loading tests were conducted on short-column CFT members with constant vertical loads. As a result, it was confirmed that they show a flexural failure mode, but the existing design method overestimates their bending capacity. Therefore, a new evaluation method was proposed for their bending capacity and deformation performance.
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), 2019
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), 2016
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering & Earthquake Engineering (SE/EE)), 2016
Journal of Japan Society of Civil Engineers, Ser. A1 (Structural Engineering ^|^ Earthquake Engineering (SE/EE)), 2013
Geosynthetics Engineering Journal, 2016
Journal of JAEE, 2015
Most seismic damage of steel railway bridges tends to occur in their bearings, particularly that ... more Most seismic damage of steel railway bridges tends to occur in their bearings, particularly that of skewed bridges. From this fact, it is considered that the acting force to the bearing of the skewed bridge is relatively larger than that of the straight bridge. However, only a few studies focusing on the acting force of the skewed bridge are available. In this paper, static and dynamic analysis of real structures with different structural type, skew angle and span length were conducted in order to clarify the behavior and acting force of bearing. As a result, it was found that the acting force concentrated on the bearing at obtuse corner because of the supplemental acting force caused by the difference of deflection between the two main girders. It was also clarified that the bias of the acting force became larger as the out-of-plane stiffness decreased.
Quarterly Report of RTRI, 2017
Steel truss bridges consists of many different trussed members and it is important to clarify the... more Steel truss bridges consists of many different trussed members and it is important to clarify the possibility of bridge collapse following the fracture of a member. This study evaluates the safety margin on a standard steel railway through-truss bridge after the fracture of certain members, using 3-D finite element analysis. Results showed that the safety margin remains fairly high with surviving members after the fracture of lower chord members, because floor members can make up for the lost sectional force from the fractured members. Finally, the degree of importance of each member was evaluated.
IABSE Symposium, Bangkok 2009: Sustainable Infrastructure - Environment Friendly, Safe and Resource Efficient, 2009
Railway steel bridges, which exceed their design lifetime, are increasing in Japan and some of th... more Railway steel bridges, which exceed their design lifetime, are increasing in Japan and some of them have problems such as corrosion, fatigue and noise. In this study, we proposed a method to improve a structural system of the steel bridges by integration with concrete decks. This method improves the load-carrying capacity of the girders, extends the service life, and reduces the noise. This paper describes the proposed method of concrete deck installation, connection between steel girders and concrete decks, and loading tests of girder-deck connection.
Transportation Research Record: Journal of the Transportation Research Board, 2012
Two lines of the Japanese high-speed rail (Shinkansen) were newly inaugurated in 2010 and 2011. I... more Two lines of the Japanese high-speed rail (Shinkansen) were newly inaugurated in 2010 and 2011. In the newly constructed lines, the share of steel bridges is low. The 15 steel bridges in the new lines were selected primarily because of construction conditions, such as construction space constraints, construction period, operation time, and ground conditions. To enable construction under these constraints, the steel bridges were constructed by various erection methods. For that reason, erection methods were often taken into account in the structural planning stage. This paper describes conditions and viewpoints in the selection of construction methods for high-speed rail. When construction methods are selected, cost is a primary consideration. Conventional crane erection with temporary bents, or the crane-bent method, is a basic construction method because of its low cost. If constraints that prevented the crane-bent method from being used were encountered in the construction sites, ...
International Journal of Steel Structures, 2013
Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of the... more Steel railway bridges which exceed their design lifetime are increasing in Japan, and some of them have problems such as corrosion and fatigue. In this study, we proposed a method to improve the performance, such as the load-carrying capacity, of the existing steel railway bridges by installation of concrete decks. To figure out the applicability of the proposed method, we discussed the applicable range of span and the effect of stress reduction. Considering application into actual bridges, we proposed an installation method using pre-cast concrete decks and girder-deck connection with filler mortar and steel fasteners. Finally, we carried out loading tests of the connection with fasteners and bending tests of the applied girders. As a result, we found that the girder-deck connections have enough static capacity for lateral force and train loads, under the condition that the studs are installed and the gaps between the pre-cast decks are filled with mortar.
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Papers by Masamichi Saito