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Evaluation of Multitimbered Wood Crib Supports.

PB92177377

Publication Date	1991
Personal Author	Barczak, T. M.; Tasillo, C.
Page Count	18
Abstract	The report describes the results of full-scale testing of several multitimbered wood crib configurations. Multitimbered configurations are wood cribs that are constructed with two or more timbers per layer. Nine different crib configurations were evaluated. Configuration parameters under study included the aspect ratio (height-to-width relationship) and the percentage of solid material used in crib construction. Test results and generalized wood crib behavior are discussed, and recommendations are made concerning crib constructions to maximize strength and stability. Crib performance is enhanced by reducing buckling effects by decreasing the aspect ratio and geometry considerations that increase the moment of inertia. A cost-benefit analysis of multitimbered wood crib configurations is made. Generally, increasing the percentage of solid provides more resistance at less unit construction cost. A comparison of laboratory results and underground observations of several wood pack wall supports suggests in situ load capacity is less than that measured in laboratory testing.
Keywords	Underground supporting Structural timbers Supports Crib walls Underground mines Coal mines Benefit cost analysis Loads(Forces) Stiffness Deformation Buckling Test facilities Mechanical tests
Source Agency	Bureau of Mines
NTIS Subject Category	48A - Mineral Industries 50C - Construction Equipment, Materials, & Supplies 71R - Wood & Paper Products
Corporate Authors	Bureau of Mines, Pittsburgh, PA. Pittsburgh Research Center.; Corps of Engineers, Pittsburgh, PA. Pittsburgh District.
Supplemental Notes	Library of Congress catalog card no. 90-45533. Prepared in cooperation with Corps of Engineers, Pittsburgh, PA. Pittsburgh District.
Document Type	Technical Report
Title Note	Rept. of investigations/1991.
NTIS Issue Number	199214

Evaluation of Multitimbered Wood Crib Supports.

Evaluation of Multitimbered Wood Crib Supports.
PB92177377

Publication Date	1991
Personal Author	Barczak, T. M.; Tasillo, C.
Page Count	18
Abstract	The report describes the results of full-scale testing of several multitimbered wood crib configurations. Multitimbered configurations are wood cribs that are constructed with two or more timbers per layer. Nine different crib configurations were evaluated. Configuration parameters under study included the aspect ratio (height-to-width relationship) and the percentage of solid material used in crib construction. Test results and generalized wood crib behavior are discussed, and recommendations are made concerning crib constructions to maximize strength and stability. Crib performance is enhanced by reducing buckling effects by decreasing the aspect ratio and geometry considerations that increase the moment of inertia. A cost-benefit analysis of multitimbered wood crib configurations is made. Generally, increasing the percentage of solid provides more resistance at less unit construction cost. A comparison of laboratory results and underground observations of several wood pack wall supports suggests in situ load capacity is less than that measured in laboratory testing.
Keywords	Underground supporting Structural timbers Supports Crib walls Underground mines Coal mines Benefit cost analysis Loads(Forces) Stiffness Deformation Buckling Test facilities Mechanical tests
Source Agency	Bureau of Mines
NTIS Subject Category	48A - Mineral Industries 50C - Construction Equipment, Materials, & Supplies 71R - Wood & Paper Products
Corporate Authors	Bureau of Mines, Pittsburgh, PA. Pittsburgh Research Center.; Corps of Engineers, Pittsburgh, PA. Pittsburgh District.
Supplemental Notes	Library of Congress catalog card no. 90-45533. Prepared in cooperation with Corps of Engineers, Pittsburgh, PA. Pittsburgh District.
Document Type	Technical Report
Title Note	Rept. of investigations/1991.
NTIS Issue Number	199214