Evaluation of the Load-Carrying Capacity in Bending of Large Cross Section “Pitch Pine” Beams in Standing Structures

Abstract

This paper deals with the procedure followed in order to define a visual grading protocol to determine the mechanical properties of existing old pitch pine timber beams with large sections. The commercial name pitch pine comprises several species in the group of southern yellow pines, being the Longleaf pine or Georgia pitch pine (Pinus palustris) the most important. Old growth Pinus palustris, was very much appreciated for its rigidity, density, strength properties and natural durability. In Spain, many of the buildings constructed with this timber (named as pino tea) are nowadays under rehabilitation processes which, in some cases, will change the previous use of the building. All these interventions require understanding the mechanical properties of the timber. The structural properties of the aged pitch pine timber are unknown and there is not any European stress grading standard to enable the classification of the existing elements. For this reason, a total of 45 large section pitch pine pieces were visually analyzed and graded according to Spanish standard UNE EN 56.544 [. After this, the beams were tested according to UNE EN 408 [ in order to determine their modulus of rupture and flobal modulus of elasticity. All beams were tested keeping their original positions in the building and a new classification system for old beams is proposed based on a reduced number of chief visual grading parameters and taking into account their position into the beam.