Blog Archives

Analytical Models

Posted by on 20/ 11/ 15

A few material models have been proposed for the development of plastic strains in unbound granular materials in a pavement structure. Lashine et al. (1971), and Barksdale (1972) tested unbound granular material in a repeated load triaxial test for 100 000 cycles. They found that the permanent axial deformation, єpb at different

Fig. 9.4 Example of stress-strain cycles obtained in a repeated load triaxial test on a granular material (Hornych et al., 1998)

stress states is proportional to number of load cycles, N (Fig. 9.4). Since 1971, many analytical models have been developed and most of them are listed by Lekarp and Dawson (1998).

However, these models have never been used with finite element (FE) calcula­tions except the Hornych model (Hornych et al...

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When Two Beams Meet Over a Post

Posted by on 20/ 11/ 15

Where any two beams meet over a post, there are many ways, short of matrimony, to join them together. Traditional timber framers have a variety of joints to use in this situation, including an assortment of “scarf” and “dovetail” joints — these take practice — and half-lap joints, as in Fig. 4.14. Lap joints are not too difficult to make with common tools, and you may like to have a go at them. A drawback, however, is that shear strength of the beam is diminished when it is cut half way through. In fact, weakening of structural members is almost always the case with any traditional joint. Another example of this would be an eight-by-eight-inch beam with a tenon of two-by-eight-inch cross-section carved into its end for insertion into the mortise of an adjacent post...

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ALERT

Posted by on 20/ 11/ 15

Dielectric unions have insu­lators inside that will not con­duct electricity. If your electrical system is grounded to the water main and you install a dielectric union to join copper pipe to a galvanized steel service pipe, for example, install a bonding jumper to ensure continuous grounding.

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Water-supply pipe supports. Clockwise from upper/eftvtwo Acousto-Plumb® clamps (which reduce pipe noise by cushioning vibrations), a copper pipe strap, a 3A-in. by 6-in. plastic-coated wire hook, two plastic suspension clamps, and a felt-lined J-clamp.

Подпись: After running DWV branch drains to fixtures, install supply-pipe assemblies and solder stub-outs to perforated strap.image599

less. Support horizontal runs of CPVC supply pipe every 3 ft.; vertical runs should be suported every 10 ft., with clamps or plumber’s strap attached to blocking. Support PEX tubing every 32 in. on horizontal runs and every 10 ft...

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CURBS AND GUTTERS

Posted by on 20/ 11/ 15

Curbs and gutters convey rainfall into storm drainage systems, which are discussed in the next section. There are, however, less costly alternatives to the traditional vertical curb and gutter construction.

Following are guidelines for curbs and gutters:

• Substitute grassy swales for curbs and gutters.

• Where curbs are installed, build rolled curbs rather than traditional vertical curbs.

• Reduce the width of concrete gutters or eliminate them entirely.

• Eliminate reverse-flow curbs and gutters in parking lots, or replace them with asphalt curb, header curb, wheel stops, or integral curb/sidewalks.

• With concrete vertical curbs, use extruded construction rather than formwork.

Подпись: Grassy SwalesПодпись: Typical roadside swaie Grassy swales are depressed areas running parallel to the street that serve in lieu of curbs and gutt...

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Long Term Elasto-Plastic Behaviour

Posted by on 20/ 11/ 15

Routine pavement methods are mechanistic-empirical design methods, based on linear elastic calculations. Usually, the only rutting criterion to be used concerns the subgrade soil, and consists in limiting the vertical elastic strains at the top of the subgrade. Rarely is a criterion applied for the unbound granular layers although Dawson and Kolisoja (2004) have shown that in roads with thin bound layers, the road’s rutting will largely be the consequence of plastic deformation in the granu­lar layers. Similarly, it is rare for a plastic criterion to be used in design probably because of the much greater difficulty in computing plastic strain fields.

Advanced pavement models are based on the main tests for unbound granular materials: the monotonic triaxial test and the repeated load tri...

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TESTING THE DWV SYSTEM

Posted by on 20/ 11/ 15

Once you’ve roughed out the DWV system, but before hooking up fixtures, test for leaks. Filling DWV pipes with water is a common test, which requires that you seal all fixture stub-outs and use a garden hose to fill the largest stack. (All DWV pipes are interconnected, so you need fill only one stack to fill all.) Should you see leaks, drain the system, fix the leaks, and refill. Once

Подпись: SAFETY ALERT Electrical service is often grounded to metal water-supply pipes. Thus they may be energized. To avoid shocks when cutting into such pipes, use a cordless reciprocating saw with a metal-cutting blade, rather than a corded saw. The cordless saw's plastic casing will also insulate against shocks if pipes are energized, as will rubber gloves. Before cutting, shut off the water and open faucets to drain the pipes. llllll Подпись: When filling the DWV system for testing, use a double dynamiter to block the combo fitting at the base of the main drain. Testing plugs. Clockwise, from bottom: 1 ’A-in. test plug, 3-in. test plug, 4-in. test plug, and "jim cap." The first three plugs insert into pipes and expand via a wing nut; the jim cap slips over the outside of a pipe and tightens with a band clamp. you see no leaks, allow the water to stand at least overnight or until the inspector signs off on your system.

There are several types of pipe seals. The most common and least expensive is a glue-on cap that fits inside a DWV pipe stub. Allow pipe cement to dry a day before filling pipes with water...

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Adhesives for Wood Flooring

Posted by on 20/ 11/ 15

Use only solvent-free adhesives or 100 percent silicone. Refer to the section on wood adhe­sives in Division 6.

Finishes for Wood Flooring When finishing or refinishing a wood floor on­site, it is advisable to specify “dustless” sand­ing, as explained above. This technique will help lower the amount of dust generated, but a thorough vacuuming with a true HEPA (high efficiency particulate air) vacuum will still be required.

A wide variety of floor-finishing prod­ucts are available, some with very toxic in­gredients. Because the floor is usually one of the last things to be finished, these emissions can be readily absorbed into other porous fin­ishes and may continue to outgas for weeks or months before the finish is fully cured...

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Learn More about the Principles of Siting a House

Posted by on 20/ 11/ 15

For more information on siting principles, additional detailing, and solar-design strate­gies for houses, as well as the mathematical formulas required to analyze these strate­gies for their potential energy savings, check out the second edition of Sun, Wind & Light: Architectural Design Strategies by G. Z. Brown and Mark DeKay (John Wiley & Sons Inc., 2000).

Although out of print, another good resource available at used-book stores and libraries is Climatic Building Design: Energy – Efficient Building Principles and Practice by Donald Watson and Kenneth Labs (McGraw – Hill, 1993). Both books contain a wealth of helpful charts, meteorological data, and ex­amples of solar siting and building design.

M. Joe Numbers is an architect with Gile-Buck & Associates in Boise, Idaho.

Подпись:Guidelines fo...

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Mediterranean ports in the Roman period

Posted by on 20/ 11/ 15

Under the Republic, the Roman provinces were resources to be exploited for the sole benefit of Italy. Later on, the emperors came to understand that the cohesion of the Empire depended on the prosperity of the provinces. As the 2nd and 3rd centuries of our

era unfolded, the economic situation of the provinces flourished; a number of them offi-

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cially declared their wish that “the Roman domination should last eternally.” Maritime navigation is the most effective link among these provinces, and also the most economical. Transport ships plow the Mediterranean Sea, the mare nostrum of the Romans, at least during the warm season – from September to May navigation is offi­cially forbidden on the mare closum. In reality, the navigation period is between March and November...

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Make the Wind Work for You

Posted by on 20/ 11/ 15

Generally, summer and winter winds come from different directions. It’s usually pos­sible to divert winter winds and to channel
summer breezes by carefully locating the house in relation to its surroundings. Check with your local airport, meteorological sta­tion, or state energy office to determine the prevailing summer – and winter-wind direc­tions for your area. Also, this data can be obtained from the U. S. Department of Com­merce National Climatic Center in Asheville, N. C. (www. ncdc. noaa. gov/oa/climate/ climatedata. html).

Make the Wind Work for YouStudy the adjacent topography, trees, and buildings during your initial site inspection. Look for those existing conditions that can block or divert cold winter winds around the building site. Locate the house in these lee – side areas (see the top drawing on ...

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