Timber structures. Structural timber and glued laminated timber. Determination of some physical and mechanical properties

The interest in replacing native wood with fast growing reforestation wood is recurrent, aiming at larger quantities of material in less time with no losses in its resistive properties. This paper consists in comparing the behavior of in natura structural timber parts with glued laminated timber, made with polyurethane resin based on castor oil, with regard to the resistance to axial compression. The assembly process of these pieces aims to achieve a similar or even superior resistance to the solid ones, considering that the MLC method allows the construction of structural pieces of many sizes and formats using different pieces of wood. Two this end, two species of wood, Pinus and Eucalyptus will be compared. The polyurethane resin, manufactured by the company Imperveg, was used in the process of glueing the stacks together. Evaluations will be performed according to NBR7190 (1997) aiming to characterize the physical and mechanical properties of the pieces and the results obtained will be submitted to statistical analysis by the Anova method.

Download Full-text

Basic set of experiments for determination of mechanical properties of sand

Bulletin of the Polish Academy of Sciences Technical Sciences ◽

10.2478/bpasts-2014-0015 ◽

2014 ◽

Vol 62 (1) ◽

pp. 129-137

Author(s):

A. Sawicki ◽

J. Mierczyński

Keyword(s):

Mechanical Properties ◽

Soil Mechanics ◽

Physical And Mechanical Properties ◽

Local Strain ◽

Initial State ◽

Laboratory Equipment ◽

Additional Information ◽

Basic Set ◽

Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

Download Full-text