Feasibility of Knots to Reduce the Maximum Dynamic Arresting Load in Rope Systems

Martin, Daniel A.; Boron, Kevin; Obstalecki, Mark; Kurath, Peter; Horn, Gavin P.

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https://hdl.handle.net/2142/101894 Copy

Description

Title

Feasibility of Knots to Reduce the Maximum Dynamic Arresting Load in Rope Systems

Author(s)

• Martin, Daniel A.
• Boron, Kevin
• Obstalecki, Mark
• Kurath, Peter
• Horn, Gavin P.

Issue Date

2015-04-07

Keyword(s)

• Firefighters
• Life safety
• Firefighting research
• Ropes
• Life safety rope
• Knots
• Falls

Abstract

Impact loads to the human body due to falls from height can be mitigated by well-designed and characterized fall protection systems. While energy absorption methods using rope deformation and/or accessory components have previously been evaluated, the ability for simple knots tied in the system to alter impact loads has not been studied in detail. We quantify the effectiveness of various common knots to reduce dynamic loads in typical fall scenarios for which the systems are designed, and interpret this change in the context of rope strength reduction due to the knot. Knots are shown to significantly (45–60 %) reduce the quasistatic strength of rope when compared to a manufactured sewn-eye (40 %). A single exception to this outcome is with the quadruple overhand on a bite (30–35 %). Knots significantly reduce the maximum arresting load due to a dynamic impact event when compared to ropes without knots, providing significantly more energy absorption than the sewn-eye alone. In nearly all rope/knot combinations, the ratio of maximum arrest load (MAL) to breaking strength was lower with the knotted ropes when compared to the sewn-eye terminations. In particular, the quadruple overhand on a bite tied in the Technora–Technora rope resulted in MALs that were only 33 % of the minimum breaking strength (MBS). Ropes with sewn-eye terminations resulted in MALs that were 80 % of the MBS. From the scenarios investigated, the quadruple overhand on a bite provides a favorable reduction in arrest loads with the smallest associated loss of strength.

Publisher

Journal of Dynamic Behavior of Materials

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/101894

DOI

10.1007/s40870-015-0015-5

Sponsor(s)/Grant Number(s)

This research was funded by the Department of Homeland Security’s Assistance to Firefighters Grant Program’s Fire Prevention and Safety Grants through Grant # EMW-2008-FP-02504.

Copyright and License Information

Copyright Society for Experimental Mechanics, Inc 2015

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