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PDF| EXPRESSED IN POUNDS PER SQUARE INCH |
| (From Manual of the American Railway Engineering Assn., 1911, p. 153) |
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-----------------------------------------------------------------------------------------------------------------------| | NOTE.--The working unit-stresses given in the table are intended for railroad bridges and trestles. For highway bridges and trestles the unit-stresses may be increased | | twenty-five (25) per cent. For buildings and similar structures, in which the timber is protected from the weather and practically free from impact, the unit-stresses may be | | increased fifty (50) per cent. To compute the deflection of a beam under long-continued loading instead of that when the load is first applied, only fifty (50) per cent of the | | corresponding modulus of elasticity given in the table is to be employed. | |-----------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------| | | BENDING | SHEARING | COMPRESSION | | | |---------------------------------+-------
----------------------------------+-------------------------------------------------------------------------| Ratio | | | Extreme | Modulus of | Parallel to | Longitudinal | Perpendicular | Parallel to | For | Formulae for | of | | | fibre | elasticity | the grain | shear in | to the grain | the grain | columns | working stress in | length | | KIND OF | stress | | | beams | | | under 15 | long columns over | of | | TIMBER |--------------------+------------+-------
-------------+--------------------+--------------------+--------------------| diameters | 15 diameters | stringer | | | Average | Working | | Average | Working | Elastic | Working | Elastic | Working | Average | Working | working | | to | | | ultimate | stress | Average | ultimate | stress | limit | stress | limit | stress | ultimate | stress | stress | | depth | |-----------------+----------+---------+------------+-------
---+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------|
-----------------------------------------------------------------------------------------------------------------------| | NOTE.--The working unit-stresses given in the table are intended for railroad bridges and trestles. For highway bridges and trestles the unit-stresses may be increased | | twenty-five (25) per cent. For buildings and similar structures, in which the timber is protected from the weather and practically free from impact, the unit-stresses may be | | increased fifty (50) per cent. To compute the deflection of a beam under long-continued loading instead of that when the load is first applied, only fifty (50) per cent of the | | corresponding modulus of elasticity given in the table is to be employed. | |-----------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------------| | | BENDING | SHEARING | COMPRESSION | | | |---------------------------------+-------
----------------------------------+-------------------------------------------------------------------------| Ratio | | | Extreme | Modulus of | Parallel to | Longitudinal | Perpendicular | Parallel to | For | Formulae for | of | | | fibre | elasticity | the grain | shear in | to the grain | the grain | columns | working stress in | length | | KIND OF | stress | | | beams | | | under 15 | long columns over | of | | TIMBER |--------------------+------------+-------
-------------+--------------------+--------------------+--------------------| diameters | 15 diameters | stringer | | | Average | Working | | Average | Working | Elastic | Working | Elastic | Working | Average | Working | working | | to | | | ultimate | stress | Average | ultimate | stress | limit | stress | limit | stress | ultimate | stress | stress | | depth | |-----------------+----------+---------+------------+-------
---+---------+----------+---------+----------+---------+----------+---------+-----------+-------------------+----------|
