Report of Investigations 9494: Design Methods to Enhance the Capacity, Stiffness, and Timber Utilization of Wood Cribs

Details

• Journal Article:
  Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9494
• Personal Author:
  Barczak, Thomas M. ; Gearhart, David F.
• Description:
  This U.S. Bureau of Mines report describes methods to enhance the capacity, stiffness, and timber utilization of wood crib supports. Since stiffer supports minimize strata deflections that contribute to roof instability, efforts to maximize crib stiffness while maintaining stability through a wide displacement range should be a design priority. The stiffness and capacity of conventional crib designs, employing alternating layers of wood timbers that are loaded perpendicular to the grain, can be increased by increasing the interlayer contact area or by using higher strength wood. Contact area can be increased by using wider timbers or employing more timbers per layer. Concepts that provide parallel-to-the-grain timber loading will provide substantial increases in crib stiffness and capacity. Two concepts that utilize this principle are examined: (1) an original South African design that constructs wood cribs from preformed layers (mats) of timber where short blocks are oriented vertically between horizontal slabs; and (2) a design that employs full lengths of timber placed vertically in the interior of a conventional crib structure. These designs also provide more efficient timber utilization by providing greater support capacity per volume of wood used in the crib construction. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  Shoring; Structural-timber; Stiffness; Mechanical-properties; Oak-wood; Poplar-wood; Mine-safety; Strata-control; Roofs; Compressive-properties; Design-criteria; Birch-wood; Hardwoods; Softwoods; Crib-walls; Coal-mines; Wooden-structures; Mining-industry; Underground-mining
• Source:
  Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9494, 1994 Jan; :1-15
• Series:
  NIOSH Numbered Publications   ; Mining Publications  
• Subseries:
  Report of Investigations
• ISSN:
  1066-5552
• Document Type:
  Text
• Genre:
  Report
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PRC - Pittsburgh Research Center
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  21 pdf pages
• NIOSHTIC Number:
  nn:10012276
• NTIS Accession Number:
  PB94-127867
• Federal Fiscal Year:
  1994
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f3188a620ee44e626a1580285e3874ffa6332ed67bed931a3054f90e03e19c33f45273af45ec36648eed4df221a1fa25dfa5ddb4b6e19be443ceaddb9e0b6f07
• Download URL:
  https://stacks.cdc.gov/view/cdc/10088/cdc_10088_DS1.pdf
• File Type:
  [PDF - 1.29 MB ]