A method for approximating distributions of mechanical properties for structural lumber

Graduation date: 1975The present method of design for walls does not\ud accurately predict the strength and stiffness of walls\ud because load sharing and composite action are not taken\ud into consideration. This results in the use of higher\ud strength materials and walls which are overdesigned.\ud A new method of design for walls using finite element\ud analysis is being developed (16). This method accounts for\ud load-sharing and composite action in wall systems. To\ud apply this new method the strength and stiffness\ud distributions of the population of studs from which a\ud wall system is formed must be estimated.\ud In this study, regression models were developed to\ud predict distributions of certain mechanical properties of\ud stud grade Douglas fir studs using stress at proportional\ud limit and conventional modulus of elasticity as independent\ud variables. These regression models were used to\ud predict similar mechanical properties of utility grade\ud Engelmann spruce studs with known properties to test the\ud reliability of the model