Blog Archives

Earth Pressure and Surcharge Loadings

Posted by on 24/ 11/ 15

The choice of lateral earth pressures used for design should take into account the method and sequence of construction, rigidity of the wall-anchor system, physical characteris­tics and stability of the ground mass to be supported, allowable wall deflections, space between anchors, anchor prestress, and potential for anchor yield. For stable ground masses, the final lateral earth pressures on a completed wall with two or more levels of anchors constructed from the top down can be calculated using the apparent earth pres­sure distributions shown in Fig. 8.50. For unstable or marginally stable ground masses, design earth pressures will be greater than those shown in Fig. 8.50. Therefore, loads

APPARENT EARTH

SOIL TYPE PRESSURE DISTRIBUTION

H = final wall height Ka = active earth pressure c...

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SPRAY-PAINTING BASICS

Posted by on 24/ 11/ 15

The information in this section is generally true for all spray applications. You’ll find other sug­gestions later in this chapter.

Wear a respirator mask with two replaceable organic-vapor filters. If you’re spray-painting exteriors, a half-face mask should be adequate. For interiors, where paint concentrations build up quickly, wear a full-face respirator mask.

Never touch a spray tip while it’s spraying:

It will inject paint into your skin (and blood­stream), which requires immediate medical attention, including removing the affected skin.

Carefully mask off everything you don’t want painted—from ceilings to windows to shrubs. To protect large expanses, use 112-in. painter’s mask­ing tape to attach high-density plastic sheeting...

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ANCHORED WALL DESIGN

Posted by on 24/ 11/ 15

Anchored walls are made up of the same elements as cantilevered walls but are fur­nished with one or more tiers of anchors for additional lateral support. Anchors may be either prestressed or dead-man type. Tendons or bars extend from the wall face to a region beyond the active zone where they are grouted in place or mechanically anchored. Such walls are typically constructed from the top down in cut situations rather than fill conditions. Figure 8.49 illustrates an anchored wall and defines terminology.

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WATER SUPPLY

Posted by on 24/ 11/ 15

Alternatives to traditional standards, materials, and procedures used in residential water supply systems are often more cost efficient.

Following are guidelines for water supply:

• Consider alternative materials for water mains and service pipes.

• Use multiple connections to one common service where feasible.

• Size water distribution pipes to meet the projected need.

• Substitute blow-off mechanisms for some, fire hydrants.

• Consider alternative meter arrangements.

Подпись: Water MainsПодпись: PVC pipeWATER SUPPLYPressure water pipe has been constructed of concrete, vitrified clay, lead, ductile iron, cast iron, asbestos cement, and wood. The newest material, plastic, most often in the form of polyvinyl chloride (PVC) or polybutylene (PB), has performed equally well or better than many of the more "traditional" materials.

P...

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The great Yellow River dike failures in the Han Empire

Posted by on 24/ 11/ 15

The Yellow River dikes are continually maintained and raised. In the 2nd century BC, they had already attained a height of some ten meters. The regions they protect along the lower course of the river had become among the most populated of all China, as we have seen earlier. A first dike rupture occurred in 168 BC at a place called Suangao to the northwest of Kaifeng, near the origin of the Ji River (Figure 8.9). This rupture destroys what was called at the time the “metal dike”, to the east of Suangao, but in the end the breach is repaired.[414]

Yet again in 132 BC the Yellow River broke through its dikes at Huzi and poured out onto vast agricultural regions to the south...

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Framing Tips for Every Task

Posted by on 24/ 11/ 15

When the lead framer is assigning tasks, he has to decide what information he has to tell the framer before starting the task. If the crew member has never done the task, the lead framer needs to explain it. If the framer has done this task many times, little needs to be said. If the framer’s knowledge is not clear, it’s best to review the task with him.

There are certain “tips" that experienced framers have developed for each task. Use the ones provided in this section or keep your own list to help your crew members.

Building Wall Tips

Material Movement for Walls

1. Locate wall framing so that once the wall is built, it can be raised into position as close to where it finally goes as possible.

2...

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Theatrical Fog Machine

Posted by on 24/ 11/ 15

Certain parts of the home, such as garages, at­tics, and crawl spaces, should be completely sealed from the rest of the house in order to prevent the passage of contaminated air into living spaces. One easy way to test for leaking airflow is to use a theatrical fog machine. This is the same equipment used onstage and in movies to create fog for special effects and can be rented from most theatrical supply com­panies. Place the unit in the area to be tested, turn it on to fill the space with fog, and then observe the adjoining areas for signs of fog that indicate where leaks must be sealed.

When testing the garage, seal the door and the open vents with tape and plastic to pre­vent the fog from escaping. The same can be done for attic and crawl-space vents and other
intentional openings to...

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Overall Stability

Posted by on 24/ 11/ 15

The overall stability of slopes in the vicinity of walls is considered part of the design of retaining walls. The overall stability of the retaining wall, retained slope, and foun­dation soil or rock can be evaluated for all walls using limiting equilibrium methods of analysis. AASHTO gives the following requirements:

A minimum factor of safety of 1.3 shall be used for walls designed for static loads, except the factor of safety shall be 1.5 for walls that support abutments, buildings, critical utilities, or other installations with a low tolerance for failure. A minimum factor of safety of 1.1 shall be used when designing walls for seismic loads...

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BRUSH BASICS

Posted by on 24/ 11/ 15

The pros work steadily and methodically and note what works and what doesn’t. The following tips will help you keep the job moving and get great results.

Подпись: As you load your brush, dip it only ’/> in. to 1 in. into the paint before tapping the tip sharply against both sides of the pail to remove the excess. Подпись: Smart painters recycle brushes. This one began life as a finish-coat brush. Then, as it got tired and splayed, it was used for primer coats. When its bristles became too crusty and its handle separated from the ferrule, it became a duster. Подпись: with an initial upstroke, excess falls back onto the roller cover.

Acclimate a new brush. Stand a new brush in 1 in. of oil-based paint for 5 minutes. After absorbing a bit of paint, the new bristles will release paint more readily when you start to work. Whereas thirsty new brushes may drag at first. It’s not necessary to acclimate brushes when using latex, which works into bristles within 20 seconds to 30 seconds.

Avoid overloading your brush. Most pros have only h in. to 1 in. of paint in the bottom of a paint pail when edging—and the same amount on the tip of the brush. With this small amount, you’ll cut a cleaner paint line and keep paint off the brush handle and your hands...

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ASPHALT-SHINGLE VALLEY

Posted by on 24/ 11/ 15

RiDGE SHiNGLES MADE FRoM

1/з of field shingle FoLDED oVER RiDGE &

 

EXTEND FIELD SHiNGLES To RiDGE.

 

ASPHALT-SHINGLE VALLEYASPHALT-SHINGLE VALLEY

Подпись: CLOSED-CUT VALLEYASPHALT-SHINGLE RIDGE

For centuries, wood shingles have been used exten­sively for roofing, and they continue to be very pop­ular. However, with the advent of the asphalt shingle, they have recently lost their dominance as a roofing material. Furthermore, their use continues to decline because of cost increases and a drop in the quality of the raw materials.

Roof shingles are made predominantly from clear western red cedar, but are also available in redwood and cypress. They are sawn on both sides to a taper, and have a uniform butt thickness. Standard shingles are 16 in. long; 18-in. and 24-in. lengths are also avail­able...

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