Blog Archives

ROOM

Posted by on 20/ 11/ 15

Basic Design for Porches, Decks, and Landings

The porches on Habitat houses are among their nicest features. All Habitat houses have a covered porch of some sort. On the Charlotte house, there’s a small porch tucked underneath the main roof, sheltering the main entry door. The side door has a landing that could grow into a larger deck sometime in the future (see the photo on the facing page). Most of the Habitat houses I’ve worked on out West have a porch as an attached structure. It has its own roof, which joins either the main roof or the gable end of the house (see the top photo on p. 178). In almost any form, a porch adds something special to a house. It’s a place to put some flowers, kick off your shoes when you get home from work, or just sit down and relax at any time of day.

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SIGNING AND. ROADWAY LIGHTING

Posted by on 20/ 11/ 15

PART 1

SIGNING

Brian L. Bowman, Ph. D., PE.

Professor of Civil Engineering Auburn University Auburn, Alabama

Part 1 of this chapter presents a comprehensive review of the design, construction, and maintenance of highway signs. Both single – and multiple-mounted sign supports are addressed, with an emphasis on highway safety. Breakaway supports with various types of slip bases, frangible bases, and post hinging systems are explained and illustrated. Commercially available devices and alternatives are identified and discussed. Guidelines on use and construction are summarized. An extensive list of references, which are noted in the text, concludes the section...

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Moving a wall in

Posted by on 20/ 11/ 15

Moving a wall in

SHEATHING THE WALL

Anyone who has witnessed the damage caused by an earthquake or high wind knows the importance of properly in­stalled interior and exterior wall sheathing (shear walls). In the serious 1992 Northridge quake near Los Angeles, shear walls saved many buildings—and many lives.

Wall sheathing provides strong lateral (horizontal) and vertical strength. It helps hold buildings together. It also helps make a house windproof, which is espe­

cially important if you live where cold winds are a reality. The most common sheathing materials are exterior-grade plywood and OSB.

Most building codes allow wall sheath­ing to be installed vertically (see the photo on the facing page), with the long edges nailed to the wall studs...

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Finnish Example

Posted by on 20/ 11/ 15

Figure 8.10 and Table 8.1 show the weakening of a road structure after spring thaw. The stiffness modulus E2 of the whole pavement structure measured by the FWD is, on average, 13% lower in the spring time than it is before the next freezing period. According to the FWD indices, the reason is the weakening of the up­per structure. This is shown since the BCI-indices (which are a representation of deflection in the subsoil) remain about the same, but the upper structure is weak­ened: the SCI (which is a representation of near-surface deflections) rises by 22%. The reason for this is that there must be more moisture in the structure after the thawing than in late autumn. The temperature of the pavement has been taken into account in the calculation on the indices. The data is from a 5...

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Thawing, Field Study, Iceland

Posted by on 20/ 11/ 15

Figure 8.9 shows the air temperature together with the volumetric water content at Dyrastadir in Nordurardalur in SW Iceland during spring thaw, monitored through an environmental program run by the Public Roads Administration in Iceland. One can clearly see that as the thawing period starts in early March the water content increases, initially close to the surface and later at greater depth, before it slowly reverts back to normal values. As the water content affects the stiffness of the struc­ture as well as the permanent deformation characteristics, increased deterioration or damage is expected at the high water content if no axle load limitations are applied.

Fig. 8...

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Poisson distribution

Posted by on 20/ 11/ 15

The Poisson random variable is discrete, having a PMF fx(xi) = P (X = xi) given in Eq. (2.53). Dagpunar (1988) presented a simple algorithm and used the CDF-inverse method based on Eq. (6.7). When generating Poisson ran­dom variates, care should be taken so that e~v is not smaller than the ma­chine’s smallest positive real value. This could occur especially when the Poisson

parameter v is large. An algorithm for generating Poisson random variates is as follows:

1. Generate u ~ U(0,1) and initialize x = 0 and y = e~v

2. If y < u, go to step 3. Otherwise, x is the Poisson random variate sought.

3. Let u = u – y, x = x + 1, and update y = vy/x. Then go to step 2.

This algorithm is efficient when v < 20...

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PEX: The Rising Star of Supply Pipes

Posted by on 20/ 11/ 15

Подпись: In PEX water-supply installations, central manifolds distribute hot and cold water to individual fixtures or fixture groups. Flexible tubing requires far fewer fittings than do rigid materials.Подпись: PEX tubing does require specialized fittings, such as plastic support elbows at tight bends and proprietary clamps where tubing attaches to metal stubouts.

Cross-linked polyethylene (PEX) is a flexible tubing system that’s been used in Europe for radiant heating and household plumbing since the 1960s, but it wasn’t widely used in potable-water systems in North America till the late 1990s. Within 5 years, though, it had captured 7 percent of the mar­ket, even though it was unfamiliar to most plumbers and cost roughly the same as cop­per. Now approved by all major plumbing codes, PEX could overtake rigid copper pipe in popularity. And as PEX tubing, tools and tech­niques become more widespread, more and more weekend plumbers will be installing it. There’s a lot to like.

PEX Advantages

► It installs quickly...

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Working safely on a ladder

Posted by on 20/ 11/ 15

Over the years I’ve learned the hard way to be extremely wary of ladders. While they are often in­dispensable, they need to be treated with the same respect accorded a powersaw. A fall from a ladder can seriously injure or kill you, and every carpenter (and many homeowners) can tell of injuries related to a ladder mishap. Here are a few safety tips to make working on a ladder safer.

• Buy a quality ladder. Check the ladder’s label for a rating of 1 A, which means that the ladder is a heavy – duty one.

• If working near or with electrical wiring, it’s a good idea to own a nonconductive ladder. Fiber­glass is a good choice, although these are typically heavy and expensive. (Aluminum and wet wood ladders can conduct electricity.)

• Don’t stand on the uppermost steps of a ladder; g...

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UPGRADED INSULATION

Posted by on 20/ 11/ 15

WALLS

UPGRADED INSULATION

Rigid insulation, with a potential R-value approxi­mately double that of batt insulation, is a very attractive alternative for upgrading the thermal performance of walls. The material is easy to install in large lightweight sheets, has sufficient strength to support most siding and interior finish materials, and can double as an air/ vapor barrier in some cases. Its disadvantages are high cost and potential for toxic offgassing in a fire.

Rigid insulation is most effective when used on the exterior of the building because it covers the entire skin of the building continuously without the interruption of floors or interior partitions. It can act as the backing for siding but does not provide the strength to act as structural sheathing...

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Thawing, Field Study, Canada

Posted by on 20/ 11/ 15

In cold climates, and with frost susceptible materials, freeze thaw phenomena play a major role in pavement deterioration. Figure 8.8 shows examples of measurements of deflection development, and of water content in the subgrade, performed in a full scale experiment, carried out in Quebec (Savard et al., 2005). The pavement structure consists of 18 cm of bituminous materials over a granular base (40 cm) and a 40 cm thick sand frost-protection layer. The pavement is subjected to frost indices exceeding 1000°C. days. The deep frost penetration (up to 1.5 m during severe win­ters) leads to large water content variations in the silty, frost susceptible subgrade,

which considerably affect the pavement deflections...

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