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book/basics/wood/material_characteristics.ipynb
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"cell_type": "markdown",
"metadata": {},
"source": [
"# Material characteristics"
"# Material characteristics\n",
"\n",
"This section contains tables with the material properties of the different timber strength classes. With the aid of a modification factor the characteristic values are adapted to the local environment and use.\n",
"\n",
"## Durability class\n",
"\n",
"The upper table below can be used to judge whether wood species belonging to a particular durability class (D1-D5) is sufficiently durable or needs extra protection. The durability class of different wood species is depicted in the lower table below. The higher the durability class, the less durable a wood species.\n",
"\n",
"| Use class | D1 | D2 | D3 | D4 | D5 |\n",
"|----|----|----|----------|----|----|\n",
"| 1 | O | O | O | O | O |\n",
"| 2 | O | O | O |(O) |(O) |\n",
"| 3 | O | O | (O) |(O)-(X)|(O)-(X) |\n",
"| 4 | O |(O) | (X) | X | X |\n",
"| 5 | O | X | (X) | X | X |\n",
"\n",
"O: Natural durability is sufficient \n",
"(O): Natural durability in principle sufficient but some circumstances require wood treatment \n",
"(O)-(X): Natural durability can be sufficient \n",
"(X): Chemical treatment is advisable but for some applications the natural durability can suffice \n",
"X: Chemical treatment is necessary\n",
"\n",
"| Species | Natural durability |\n",
"|-------------------|---------------------|\n",
"| Spruce | D4 |\n",
"| Pine | D3-D4 |\n",
"| Oak (European) | D2 |\n",
"| Oak (American) | D4 |\n",
"| Larch | D3-D4 |\n",
"| Azobe | D2 |\n",
"| Robinia | D1-D2 |\n",
"| Western Red Cedar | D2-D3 |\n",
"\n",
"## Use class\n",
"\n",
"| Class | Description | Example |\n",
"|-------|--------------------------------------------------------------------------------------------------------------|-------------------|\n",
"| 1 | Situations in which the wood or wood-based product is inside a construction, not exposed to the weather and wetting. | roof beam |\n",
"| 2 | Situations in which the wood or wood-based product is under cover and not exposed to the weather (particularly rain and driven rain) but where occasional, but not persistent, wetting can occur. | beam of open canopy |\n",
"| 3 | Situations in which the wood or wood-based product is above ground and exposed to the weather (particularly rain) | external column |\n",
"| 4 | A situation in which the wood or wood-based product is in direct contact with ground and/or fresh water | foundation pile |\n",
"| 5 | A situation in which the wood or wood-based product is permanently or regularly submerged in salt water (i.e. sea water and brackish water) | sea lock gate |\n",
"\n",
"## Service classes\n",
"\n",
"| Service class | Environment | R.H. in construction* | Use class |\n",
"|---------------|-------------------------|----------------------------|-----------|\n",
"| 1 | Relative humidity exceeding 65% only a few weeks per year. Temperature 20°C, | 12% R.H. | 1 |\n",
"| 2 | Relative humidity exceeding 85% only a few weeks per year. Temperature 20°C | 20% R.H. | 1 |\n",
"| 2 | If the component is in a situation where it could be subjected to prolonged wetting by liquid water e.g. condensation | 20% R.H.| 2 |\n",
"| 3 | Climatic conditions leading to higher moisture contents than in service class 2 | > 20% R.H. | 3 or higher if used externally |\n",
"\n",
"\n",
"* The relative humidity of in the material given in this column holds for most softwoods\n",
"\n",
"## Load duration class\n",
"Load duration class | Order of load duration | Example \n",
"--------------------|------------------------------|------------------------\n",
"Permanent | More than 10 years | Self weight \n",
"Long-term | 6 months to 10 years | Storage \n",
"Medium-term | 1 week to 6 months | Imposed floor load, snow\n",
"Short-term | Less than 1 week | Snow, wind \n",
"Instantaneous | - | Wind, accidental load \n",
"\n",
"## Modification factors $k_{mod}$\n",
"\n",
"| Material | Service class | Permanent | Long-term | Medium-term | Short-term | Instantaneous |\n",
"|----------------------------|---------------|-----------|-----------|-------------|------------|---------------|\n",
"| Solid Timber and Glued Laminated Timber | 1 | 0.60 | 0.70 | 0.80 | 0.90 | 1.10 |\n",
"| Solid Timber and Glued Laminated Timber | 2 | 0.60 | 0.70 | 0.80 | 0.90 | 1.10 |\n",
"| Solid Timber and Glued Laminated Timber | 3 | 0.50 | 0.55 | 0.65 | 0.70 | 0.90 |\n",
"\n",
"\n",
"Note that the modification factor needs to be chosen according to the load duration of the whole load combination.\n",
"\n",
"## Creep factors $k_{def}$\n",
"The creep factor is based on the service class.\n",
"\n",
"| Material | 1 | 2 | 3 |\n",
"|----------------------------|-----|-----|-----|\n",
"| Solid Timber and Glued Laminated Timber | 0.60 | 0.80 | 2.00 |\n",
"\n",
"\n",
"## Material properties: solid timber\n",
"\n",
"## Material properties: glued laminated timber\n",
"\n",
"## Material properties: solid timber\n",
"\n",
"## Design values of material properties in ULS\n",
"\n",
"## Final deflection\n",
"\n"
]
},
{