Blog Archives

Layering: Shining New Light on the Old Rules

Posted by on 24/ 11/ 15

While new ways of producing light offer lots of design possibilities, it still makes sense to stick with the tried-and-true basics of light
layering that designers have long relied on to produce attractive, well-lit spaces. Light layering incorporates four specific types of lighting to create a well-lit environment: task, accent, decorative, and most impor­tant, ambient light. The rule here is that more than one light source is needed to illuminate a room properly. The challenge when working with new, energy-efficient types of lighting is that you have to go be­yond light layering and understand how these new sources create light in order to use them correctly.

For example, CFLs, CCFLs, and ESLs (see "Low-Energy Lighting: The Latest Bulb Technologies" on the facing page) are omnidirection...

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INSTALLING CROWN MOLDING

Posted by on 24/ 11/ 15

Crown molding dresses up the wall-ceiling joint, as do its fancy cousins cornices, which are formed from several boards. Crown molding can be as simple as a single piece of shaped trim angled along the corners of the ceiling, or you can pair it with a backing trim to ensure a solid nailing sur­face, which is not always present in an old houses with irregular framing and springy plaster.

Start by locating and marking stud and joist centers on the walls and ceilings. Where joists run parallel to a wall or where you can’t find framing on a regular nailing interval, install a row of triangular nailing blocks along the tops of walls, as shown above. Predrill these blocks to avoid splitting them, and nail them with 8d finish nails to the top plates or studs, spacing the blocks every 24 in...

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Structure Dimensions

Posted by on 24/ 11/ 15

MSE walls should be dimensioned as required by AASHTO. The soil reinforcement length must be at least 70 percent of the wall height, as measured from the leveling pad, but not less than 8 ft (2.4 m) for both strip and grid type reinforcement. AASHTO requires the reinforcement length to be uniform throughout the entire height of the wall. The specification does allow deviation from this uniform length requirement, subject to the availability of substantiating evidence.

MSE walls must be designed for both external stability and internal stability. The recommended minimum factors of safety in various areas of external stability are noted in AASHTO as follows:

External stability

Factor of safety

Overturning

2.0 for footings on soil, >1.5 for

footings on rock

Ultimate bearin...

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Optimization of System Reliability

Posted by on 24/ 11/ 15

As described in Chap. 5, reliability of a multicomponent system depends on the component reliability, number of redundant components, and the arrangement of the components. With everything else remaining fixed, the system reliability gets higher as the number of redundant components increases. However, noth­ing is free—achieving higher system reliability has to be paid for by a higher price for the system. In general, practically all systems exhibit a behavior of diminishing rate of return as the number of redundant components increases (see Example 5.2). In the context in system reliability, this behavior is describ- able by a strictly concave function relation between the system reliability and number of redundant components (or total system cost)...

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SANITARY SEWERS

Posted by on 24/ 11/ 15

Residential neighborhoods often have overdesigned, underutilized sewer systems which local officials must review for cost reduction possibilities. Various sanitary sewer system alternatives are available today to communities using traditional, outmoded procedures, designs, and materials.

Following are guidelines for sanitary sewers:

• Use curvilinear sewers where feasible.

• Increase maximum manhole spacing.

• Use cleanouts as an alternative to manholes for maintenance.

• Use plastic pipe instead of concrete or metallic pipe.

• When appropriate, use inside drop connections.

• Design sewer pipe size and slope to meet the need.

• Use "state-of-the-art" inspection procedures.

• Use common laterals.

Подпись: Manholes, Curvilinear Sewers, CleanoutsRequiring fewer manholes than the norm, encouraging curvilinear sewer designs, ...

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PIPING COLOR CODES

Posted by on 24/ 11/ 15

Piping color codes are used when utility companies stake out piping loca­tions. For example, a yellow flag generally indicates one of the following types of pipe:

■ Oil

■ Steam

■ Gas

■ Petroleum

When you encounter a blue flag that indicates the location of piping be­low ground, the type of piping that you are probably dealing with is one of the following:

■ Potable Water

■ Irrigation Water

■ Slurry Pipes

Diameter

Service

Extra heavy

(inches)

weight (lb)

weight (lb)

Double hub,

2

21

26

5-ft lengths

3

31

47

4

42

63

5

54

78

6

68

100

8

105

157

10

150

225

Double hub,

2

11

14

30-ft length

3

17

26

4

23

33

Single hub,

2

20

25

5-ft lengths

3

30

45

4

40

60
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PLASTIC PIPE FOR DRAINS & VENTS

Posted by on 24/ 11/ 15

Plastic pipe for drains and vents is very common in modern plumbing. Polyvinyl Chloride Plastic Pipe (PVC) is probably used more often than any other type of drainage or vent pipe (Fig. 11.26). This type of pipe is strong and resistive to a variety of acids and bases. PVC pipe can be used with wa­ter, gas, and drainage systems, but it is not rated for use with hot water. I’ve found this type of pipe to be sensitive to dirt and water when joints are being

Подпись: Drawn (hard copper) (feet) Annealed (soft copper) (feet) Type К Tube Straight Lengths: Straight Lengths: Up to 8-in. diameter 20 Up to 8-in. diameter 20 10-in. diameter 18 10-in. diameter 18 112-in. diameter 12 12-in. diameter 12 Coils: Up to 1-in. diameter 60 lVi-in. diameter 60 100 2-in. diameter 40 45 Type L Tube Straight Lengths: Straight Lengths: Up to 10-in. diameter 20 Up to 10-in. diameter 20 12-in. diameter 18 12-in. diameter 18 Coils: Up to 1-in. diameter 60 100 lVi- and 1 Win. diameter 60 100 2-in. diameter 40 45 DWV Tube Straight Lengths: Not available All diameters 20 Type M Tube Straight Lengths: Not available All diameters 20

FIGURE 11.22 ■ Available lengths of copper plumbing tube. [Courtesy of McGraw-Hill)

Подпись: Hard copper is also known as drawn copper, while soft copper tubing is known as annealed copper.

FIGURE 11.23 ■ Tech tips.

made. The areas being joined should be dry, clean, and primed prior to sol­vent welding. Also, PVC becomes brittle in cold weather and should not be dropped on hard surfaces.

Acrylonitrile Butadiene Styrene (ABS) p...

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Facing Systems

Posted by on 24/ 11/ 15

The types of facing elements used in the different reinforced soil systems control their aesthetics, since they are the only visible parts of the completed structure. A wide range of finishes and colors can be provided in the facing. In addition, the facing provides protection against backfill sloughing and erosion, and provides drainage paths. The type of facing influences settlement tolerances. In multianchored structures, the facing is a major structural element. Major facing types include the following:

1. Segmental precast-concrete panels. Examples of these are found in Reinforced Earth, the Georgia stabilized embankment system, the California mechani­cally stabilized embankment system, the VSL Retained Earth system, the Hilfiker

TYPE TYPICAL MECHANICAL PROPERTIES

J represents the mo...

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Cutting stringers

Posted by on 24/ 11/ 15

Take a moment to check that your lay­out is correct before cutting out all the notches on the stringers. I make two cuts—the horizontal (or level) cut that rests on the floor and the vertical (or plumb) cut that nails to the top header joist. The stringer should fit snugly at both top and bottom, and all the tread lines should be level. Sometimes, espe­cially on concrete, the floor may not be dead level, which can cause the heel (back side) of a stringer to hit the con­crete first and open up a gap at the toe
(front). This results in an increase in the amount of rise on the first step up. If the floor is uneven, you’ll either have to scribe a line across the bottom of the tread and make the cut so that the stringer fits snugly to the floor or shim the heel when the front hits first.

Th...

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Longitudinal Drains

Posted by on 24/ 11/ 15

In drainage design, an undamaged asphalt surface is considered almost impervious. However, water can infiltrate into the structure through cracks and joints (see Chap­ter 5, Sections 5.3 and 5.4.2). Also, shoulders and slopes with higher permeability and high water tables can allow significant amounts of water into the structure. Whether the water arrives via cracks in the asphalt and is flowing through the pave­ment according to regime A or B, is threatening to arrive from the margins, or is simply close to the underside of the pavement due to a high phreatic surface, it is then necessary for longitudinal interceptor drains to be provided or other drains that will lower the water table or keep it in a low position. Many types of longitudinal drain are available as described in Section 13...

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