Woodworking Bench Plans
Softwoods, characterised by having naked seeds or as cone-bearing trees, are generally evergreen with needle-like leaves (such as conifers) comprising single cells called tracheids, which are like straws in plan, and they fulfil the functions of conduction and support. Rays, present in softwoods, run in a radial direction perpendicular to the growth rings. Their function is to store food and allow the convection of liquids to where they are needed. Examples of the UK grown softwoods include spruce (whitewood), larch, Scots pine (redwood) and Douglas fir.
Plywood is a flat panel made by bonding together, and under pressure, a number of thin layers of veneer, often referred to as plies (or laminates). Plywood was the first type of EWP to be invented. Logs are debarked and steamed or heated in hot water for about 24 hours. They are then rotary-peeled into veneers of 2-4 mm in thickness and clipped into sheets of some 2 m wide. After kiln-drying and gluing, the veneers are laid up with the grain perpendicular to one another and bonded under pressure in an odd number of laminates (at least three), as shown in Figure 1.9a. The outside plies, always made of veneer, are referred to as faces (face ply or back ply) and the inner laminates, which could be made of either veneers or sliced sawn wood, are called core. Examples of wood core plywood include blockboards and laminboards, as shown in Figures 1.9c-1.9e. Plywood is produced in many countries from either softwood or hardwood or a combination of both. The structural grade plywoods that are...
Hardwoods are generally broad-leaved (deciduous) trees, which often lose their leaves at the end of each growing season. The cell structure of hardwoods is more complex than that of softwoods with thick-walled cells, called fibres, providing the structural support and thin-walled cells, called vessels, providing the medium for food conduction. Due to the necessity to grow new leaves every year the demand for sap is high and in some instances larger vessels may be formed in the springwood, these are referred to as 'ring-porous' woods such as in oak and ash. When there is no definite growing period the pores tend to be more evenly distributed, resulting in 'diffuse-porous' woods such as in poplar and beech. Examples of the UK grown hardwoods include oak, beech, ash, alder, birch, maple, poplar and willow. 126.96.36.199 Hardwood characteristics Hardwoods grow at a slower rate than softwoods, which generally results in a timber of high density and strength, which takes time to mature, over 100...
In 1997, a second document implementing a PBSD methodology for the evaluation, retrofit, and rehabilitation of existing buildings was published by the Federal Emergency Management Agency (FEMA). This document and its supporting commentary is entitled NEHRP Guidelines for the Seismic Rehabilitation of Existing Buildings (ATC, 1997), and is referred to as the FEMA 273 report The work in this report involved the American Society of Civil Engineers (ASCE) and ATC under project management provided by the Building Seismic Safety Council (BSSC). The Development of Guidelines for Seismic Rehabilitation of Buildings, Phase I Issues Identification and Resolution (ATC, 1992) and the Proceedings of the Workshop To Resolve Seismic Rehabilitation Sub-Issues (ATC, 1993) documents provided recommendations and direction for the FEMA 273 report. FEMA 273 covers a broad range of building materials, including steel, concrete, masonry, and wood construction. The predecessor of the FEMA 273 report, the...
Structures determined to be in Seismic Design Category (SDC) A are required to comply only with the provisions of Section 1616.4 1 . There are five exceptions to this rule. First, detached Group R-3 dwellings in SDC A, B, and C are exempt from the general seismic provisions. Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories high with separate means of egress and their accessory structures shall comply with the International Residential Code (IBC 101.2). Second, wood frame seismic resisting systems need only conform to the provisions of Section 2308 (Conventional Light-Frame Construction). Third, agricultural storage structures intended only for incidental human occupancy do not need to be designed for seismic forces. Fourth, structures where Ss .15g and S, .04g need only comply with Section 1616.4. Similarly, structures where SDS
In the United States, Whiting, Indiana and Strasburg, Pennsylvania have used ozone in their drinking water treatment process. Other cities have run pilot studies. Ozone is used as a bleaching agent for miscellaneous items petroleum, clays, wood products, and chemical baths. It has been proposed as a bleaching agent for hair and as a disinfectant for oils and emulsions. Ozone is used to modify tryptophan and indigo plant juice. It is an important factor in colorfastness. The desulfurization of flue gases by ozone has been considered an application where it promotes liquidphase oxidation. The operations are carried out with vanadium catalysts, and the oxidation step is performed in gasfluidized beds. The desulfurizing effect of ozone on light petroleum distillates has also been reported.
The annular band of the cross-section nearest to the bark is called sapwood. The central core of the wood, which is inside the sapwood, is heartwood. The sapwood is lighter in colour compared to heartwood and is 25-170 mm wide depending on the species. It contains both living and dead cells and acts as a medium for transportation of sap from the roots to the leaves, whereas the heartwood, which consists of inactive cells, functions mainly to give mechanical support or stiffness to the trunk. As sapwood changes to heartwood, the size, shape and the number of cells remain unchanged. In general, in hardwoods the difference in moisture content of sapwood and heartwood depends on the species but in softwoods the moisture content of sapwood is usually greater than that of heartwood. The strength and weights of the two are nearly equal. Sapwood has a lower natural resistance to attacks by fungi and insects and accepts preservatives more easily than heartwood.
The most common floor decking in domestic dwellings and timber-framed buildings uses some form of wood-based panel products, for example chipboard, OSB or plywood. Solid timber decking such as softwood tongued and grooved (T&G) decking is often used in roof constructions, in conjunction with glued-laminated members, to produce a pleasant, natural timber ceiling with clear spans between the main structural members. The solid timber T&G boards are normally machined from 150-mm-wide sections with 38 to 75 mm basic thicknesses see Figure 1.18b. but larger timber section, if construction geometry permits. Alternatively, trimmers can be of hardwood or glued-laminated timber, boxed ply-webbed beams, or as shown in Figure 1.18d, composite timber and steel flitched beams. Table 1.19 Summary of the current engineered wood products and their structural applications Table 1.19 Summary of the current engineered wood products and their structural applications
Determination of some physical and mechanical properties BS EN 636 Plywood - Specifications Part 1 OSB, particleboards and fibreboard BS EN 12369-2 Wood-based panels - characteristic values for structural design. Part 2 Plywood design, materials and workmanship BS 5359 Nomenclature of commercial timbers including sources of supply BS 5756 Specification for visual strength grading of hardwood BS 8417 Preservation of timber - Recommendations
It will suffer rot and insect attack unless it is naturally durable or is protected by a preservative. In general, timber with a moisture content of over 20 is susceptible to fungal decay timber of any species kept in dry conditions will remain sound however, dry timber may be subjected to insect attack. Timber can be protected from the attacks by fungi, harmful insects or marine borers by applying chemical preservatives. The degree of protection achieved depends on the preservative used and the proper penetration and retention of the chemicals, as treatability varies among the species and also between their heartwood and sapwood. Some preservatives are more effective than others, and some are more adaptable to specific use requirements.
(e) Large span box beam and I-joists using LVL (photo courtesy of Engineered Wood products Association of Australia (EWPAA)) (f) Large span box portal frames using LVL (photo courtesy of Engineered Wood products Association of Australia (EWPAA)) (e) Large span box beam and I-joists using LVL (photo courtesy of Engineered Wood products Association of Australia (EWPAA)) (f) Large span box portal frames using LVL (photo courtesy of Engineered Wood products Association of Australia (EWPAA))
Equation (4.7c) relates to a hardwood, LVL (or glued-laminated timber) rectangular section beam subjected to a uniform moment at each end and will equate to the solution derived from equation (6.31) in EC5. With softwood rectangular sections, the ratio of E0,05 G0,05 for timber is taken to be approximately 16, and by applying this to equation (4.7a), the critical bending stress (i.e. the buckling strength), am,crit, of a rectangular softwood beam bent about its strong axis can be written as and when designing for hardwood, LVL (or glued-laminated) rectangular beams, equation (4.7c) will be as given in (4.9b), which is equivalent to equation (6.31) in EC5
Example 10.13.2 A timber-plywood gusset plate apex joint for the connection shown in Figure E10.13.2 is to be designed using 12-mm-thick Finnish birch plywood with a characteristic density of 630 kg m3 and fixed with the face grain horizontal. The joint fasteners are 3.00 mm diameter by 50 mm long smooth round wire nails, fixed without pre-drilling, with a tensile strength of 650 N mm2 and act in single shear. The timber members are strength class C18 to BS EN 338.2003 and the sizes are as shown in Figure E10.13.2. The joint will function under service class 2 conditions. The joint is subjected to design loading as shown, arising from a combination of permanent and medium-term variable actions.
Plywood Thickness of each plywood gusset plate, tp Plywood gusset plate Plywood gusset plate Characteristic density of the timber, pk pk 320 kg m3 Table 1.9, 12-mm-thick Finnish birch plywood Characteristic density of the plywood, Material factor for plywood Material factor for connections yM.plywood l-2 KM. connection 1.3 Characteristic embedment strength of the plywood, h,p,k (Table 10.6 (EC5, equation (8.20))
A Newbies Guide To Wood Working
Wonder No Longer About Things Like Designs, Tools And Safety. These Problems Among Others Will Be Covered In This E-Book. You Will Be Creating Great Wooden Works Of Art In Very Little Time At All! For The Beginning Woodworker, The Construction of Handcrafted Wood Creations Can Be a Daunting And Overwhelming Experience. Well, Not Anymore!