Service Station Drives
Service station drive approach geometry is probably the most complex of any drive design. Many of the geometric features may be used in the design of other commercial
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Blog Archives
Compression and Tension in Beams
Beam is a good catch-all word to identify a (usually) horizontal timber whose job it is to carry a load across a span. Girders and floor joists are common specific examples, as are lintels over doors and windows. Even though many roof rafters are pitched to some degree, they perform as beams, too, although other thrust considerations come into play.
Let’s load a simple but imaginary beam to see how it works. We’ll make it a rather flimsy beam so that its exaggerated performance will show what’s happening. Imagine a 12-foot long two-by-eight plank spanning — flatwise — from one support to another. If the ends of the plank are each bearing on a footwide concrete block, the clear span between supports is ten feet...
read morePhysical and Chemical Characteristics
This section describes how the material behaves. The information is useful for the design of ventilation systems and for providing adequate equipment and procedures for fire and spill containment.
• Vapor pressure tells you how much vapor the material may give off. A high vapor pressure indicates that a liquid will easily evaporate.
• Vapor density refers to the weight of the pure gaseous form of the material in relation to air. The weight of a given volume of a vapor (with no air present) is compared with the weight of an equal volume of air.
• Specific gravity tells you how heavy the material is compared to water and whether it will float or sink.
• Evaporation rate refers to the rate at which a material changes from a liquid or solid state to its gaseous form.
• Volatile o...
read moreAncient Egypt and the Arabia Felix, the rhythm of the flood seasons
Deserts border the two shorelines of the Red Sea. Along these shorelines are two countries whose verdant fringes have been struggling to resist the desert since the IVth millennium BC – two countries that are highly dependent on seasonal flood cycles. On the east there is Arabia Felix, present-day Yemen. On the west is Egypt, to which most of this chapter is devoted. The River Nile dominates and unifies the powerful and innovative Egyptian civilization. This civilization precedes the transition to the Hellenistic period and the flowering of Alexandria, described later in Part II of this book.[86]
read moreNon-destructive Methods
A number of methods exist for estimating the soil water content of road materials in a non-destructive way assuming that the instruments are placed in the road during
the construction phase. They are all indirect methods as they involve measurements of some property of the material affected by the water content or they measure a property of some object placed in the material. Some of the more common indirect methods used in the highway environment are briefly described here.
3.2.2.1 Neutron Scattering Method
In the neutron scattering method a tube acts as a radioactive source and a detector. The radioactive source is placed at the end of a rod inserted into a pre-made hole to a depth of, typically, 150 and 300 mm...
read moreEXAMPLES FROM THE DEMONSTRATION PROJECTS
Several JVAH sites used innovative approaches to foundation construction that reduced costs while maintaining structural integrity. In some cases it was necessary to provide results of soil bearing tests and engineering data to the city building department. In every case, less costly foundations resulted.
Crawl space foundations in Christian County typically are built of one course of 12x8x16 block and two courses of 8x8x16 block. The 12-inch block serves as a brick ledger. The builder, Norris "Pup" Robertson, used three courses of 8x8x16 block stacked without mortar and bound together with glass fiber reinforced surface
bonding cement. This reduced the concrete footing from 20 to 16 inches wide and eliminated 16 inches of brick veneer.
Cost savings amounted to $203 per unit for the footin...
read moreSTEP5 Build Midspan Support for Joists
Unless you arc building on a slab, yoiTlI probably need to provide midspan support for the floor joists. Without additional support somewhere between the sills, the joists can be overspanned, resulting in a finished floor that sags
or feels bouncv. A friend once :ook me
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through his 18th-century home in rural Connecticut. The beautiful, hand-hewn floor joists in the basement were fascinating—dry, free from rot and termites—but far overspanned. Upstairs, it felt like walking on ocean waves. Clearly, what was needed was some support to keep the joists from sagging and bouncing in the middle.
Codes req u і re a m і n і m u m оf 18 in. between the earth and the joists in a crawl space. These days, two systems...
read moreGETTING AROUND PROBLEMS
Getting around problems and obstacles is part of the plumbing and pipe fitting trades. Few jobs run without problems or obstacles. As any experienced piping contractor knows, there are always some obstructions in the preferred path of piping. Many times the obstacles are ductwork, but they can involve electrical work, beams, walls, and other objects are that not easily relocated. This means that the pipes must be rerouted. This section is going to deal with the mathematics required to compensate for immovable objects.
Let me set the stage for a graphic example of getting around an overhead obstruction. Assume that you are bringing a pipe up and out of a concrete floor in a basement. There is a window directly above the pipe that you must offset around. The window was an afterthought...
CUTTING SQUARE WITHOUT A SQUARE
One of the most important skills a carpenter learns over the years is training and trusting his or her eye. And one of the best ways to develop this capability is to cut square by eye. Instead of using a square to mark a 90- degree cutoff line on a board, simply make a quick pencil mark for length on the board, line up a circular saw, and make the cut. Over the course of framing a floor or a wall, this method can save you plenty of time.
If you’re comfortable using a circular saw, it’s not difficult to master this technique. Position the saw with the blade aligned on the cutoff mark and the front of the saw’s base parallel with the edge of the board. As you make the cut, keep the base parallel with the board’s edge...
read more. Step 8-Drywall Backing
2 x 4 wall
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