Gripped-End Effect in Tension Proof Testing of Dimension Lumber

摘要

The objectives of the study were (1) to predict falldown of gripped-end lumber using a computer-simulated tension strength-length effect model and (2) to measure the effectiveness of tension proof testing of lumber in the light of a gripped-end effect. In the initial tension proof test, the middle portion of each lumber specimen (nominal 2- by 6-in. No. 2 KD15 Southern Pine) was tested as if the pieces were only 10 ft long. The results confirm that gripping lumber ends in the tension proof test prevents failure of some pieces of lumber with tension strength below the proof load level. This general problem is referred to as the gripped-end effect. Although the computer model predicted falldown at a low proof load level, it failed to predict the behavior of lumber at a higher, more practical load level.