SOIL-STRUCTURAL INTERACTION AND CONCRETE TIE DESIGN

In this closure, the author summarizes several points made by the discusser which he feels are well taken. It is agreed that the analysis (which was general) should not be extended to light rail. In that context, heavier rails (132-1/yd or 66-kg/m or over) would not be economically justified. Also, the need for more data on the dynamic loads imposed on concrete, or indeed wood, ties for North American heavy wheel loading is emphasized, since dynamic loading is very dependent on track quality. (Currently in the U.S., trains with lighter wheel loads are permitted to go slightly faster poor- and medium-quality, but have no speed advantage over heavier trains on high-quality track). The discusser's point out that line loading was assumed at the rail seat, and any optimum tie length would thus be increased by only assumption made for the bearing distribution of the rail, rail pad, and tie thickness is well taken. The use of equal positive and negative moments at the two critical sections, as well as the optimization using these two critical moments as equal, were questioned by the discusser. While not agreeing with his reasons for questioning such requirements the writer basically agrees with the discusser for a practical tie design. In response to the suggestion that speed restrictions on curves generally lead to lower requirements on curves, the author notes that such restrictions are generally imposed after construction due to operating problems and never, to his knowledge, specifically specified prior to construction.

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Filing Info

  • Accession Number: 00196143
  • Record Type: Publication
  • Report/Paper Numbers: ASCE 14549 Proceeding
  • Files: TRIS
  • Created Date: Oct 17 1981 12:00AM