Revision of Model Code for Design of Concrete Railway Structures

Seiichi TOTTORI, Dr.
Senior Researcher, Laboratory Head, Concrete Structures,
Structures Technology Division

    The design standard for railway concrete structures was established in 1955, and after several revisions, the Model Code for Design of Concrete Railway Structures (hereafter called the 1992 Standard) was established in 1992, following the transition to JR.
    The 1992 Standard is applied when designing railway structures consisting of reinforced concrete and prestressed concrete structures, based on the limit state design method.
    Ministerial Ordinance Prescribing Technical Standards Related to Railways (2001), which is a technical standard of Japan, was revised from a specification prescribing type ordinance to a performance prescribing type ordinance. A transition to the same kind of design scheme for the 1992 Standard along with adjustments in line with the ministerial ordinance was also desired.
    Moreover, as much progress has been achieved in research and development for high-strength concrete and reinforcement bars, yielding advances that can now be incorporated into design standard, and as the durability of concrete structures is becoming increasingly important, expanding the content of the design standard has become a necessity. It is also necessary to incorporate other recent technologies related to concrete structures into the design standard.
    Against this backdrop, I was involved in revising the design standard as part of a research study for upgrading the railway technical standard commissioned by the Ministry of Land, Infrastructure and Transport. In conducting this revision, Committee on Design Standard for Railway Concrete Structures was organized in 2000 under the supervision of the Ministry of Land, Infrastructure and Transport, with the Railway Technical Research Institute as secretariat. After three years of deliberation, we have formed a definite plan titled "Model Code for Design of Concrete Railway Stractures (hereafter called the new standard), which is the title of this document.
    The new standard reflects the latest research in addition to the transition to a performance verification type standard. The main revisions include the introduction of a new method to calculate the impact coefficient suitable for higher speeds, a proposal for the expansion of the application scope of high-strength reinforced bars and high-strength concrete and a verification method for these materials, a proposal for a verification method for the durability of concrete structures (rebar corrosion due to chloride ions or carbonation), and reassessment of the design fatigue strength of reinforcement bars for 2 million cycles (refer to Fig. 1). It is hoped that such incorporation of the latest research available in the new standard will contribute to concrete structures that are more economical and durable.
    Following official notice by the Ministry of Land, Infrastructure and Transport, the new standard is scheduled to be published as Model Code for Design of Concrete Railway Structures toward the spring of 2004.