Mechanical properties of wood columns with rectangular hollow cross section

A rectangular hollow wood column made of Spruce-Pine-Fir (SPF) lumbers was developed, for the purpose of improving the utilization efficiency of timber. The present work conducted experimental investigations of the columns under centrically and eccentrically compression. A wide range of slenderness ratios of columns and eccentricities of loads was considered to carefully examine the failure modes in columns. The results indicated that combined material failures and buckling failures were observed for the intermediately slender columns under axial compression, while buckling failures were observed for the long columns. The ultimate strength of columns under axial compression significantly decreased with the increase of slenderness ratios. The predicted results by the tangent modulus theory closed to those of experiments. The bending failure, which underwent a pronounced nonlinear process, was the major characteristic of the intermediately slender column with an eccentric compressive load. Typically, the load carrying capacity of columns showed a decreasing trend with an increasing in eccentric ratios. Both the secondary bending and material nonlinearity were important factors that impacted the nonlinear response of the column. An analytical model was proposed for evaluating the load carrying capacity of the rectangular hollow columns under the interaction between compression and bending. There was good agreement between the results of the experiments and calculations.