Blog Archives

PARKING

Posted by on 18/ 11/ 15

Automobile parking poses a significant land use problem in subdivision planning. In the recent past, common practice provided for wide local streets, often capable of accommodating a row of parked cars on each side in addition to two lanes of moving traffic. Such parking space has often been provided where there are also private driveways and other off-street parking that can accommodate several cars. Good planning can reduce this heavy commitment of land to parking without sacrificing adequate accommodation of vehicles.

Following are guidelines for parking:

• Provide off-street parking areas whenever possible.

• Use common driveways. ‘

• Design paving thickness to meet actual parking load requirements rather than to general standards.

• Eliminate curbs and gutters in parking areas...

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Mixture Temperature during Compaction

Posted by on 18/ 11/ 15

Almost all publications on SMA underline the necessity of carefully observing the temperature of the mixture during placement and rolling. The expected range of mixture temperature is determined in different ways; it chiefly depends on the kind of binder, but such factors as the layer thickness and weather conditions are impor­tant, too. However, the most important factor is the temperature of the mixture deliv­ered to the construction site and the temperature at the end of effective compaction, below which further rolling becomes ineffective and even harmful.

Minimum temperatures for mixture supplied to a work site according to the European standard EN 13108-5 (which applies only to selected [unmodified] bitu­mens after EN 12591) are as follows:

• 160°C for paving grade bitumen 40/60...

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Embankment Construction

Posted by on 18/ 11/ 15

Where a pipe is required as part of an embankment construction, it may be installed by compacting layers of fill uniformly on either side. It is important to bring the layers up uniformly on either side of the pipe. After a sufficient layer is compacted over the top of the pipe, ordinary embankment construction may proceed. Alternatively, some agencies require that the embankment be constructed first, then a trench dug for the installation of the pipe.

5.10.1 Trench Construction

The open-trench method is commonly used for culvert construction. It is more cost – effective than tunneling except when a pipe must be constructed in an existing high fill. Shoring may be necessary, particularly if the installation is under a traveled way...

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CONSTRUCTION METHODS

Posted by on 18/ 11/ 15

Underground structures may be built by a variety of means including embankment construction, open-trench construction, jacking, tunneling, and microtunneling.

The proper design and installation of the foundation, bedding, and backfill for embankment and trench installations are critical to the performance of underground structures. They are also essential factors for achieving an accurate structural analysis of the system. The foundation preparation, bedding, and backfill of underground structures should be done in accordance with standards established by local and state transportation agencies. These standards vary from region to region, but the important aspects of typical practices are reviewed below.

Regardless of whether the pipe is installed in an embankment or a trench, the foun­dat...

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TIP

Posted by on 18/ 11/ 15

In some very old houses, you may find that the neutral wires were attached to a switch— rather than the hot wires, as required by codes today. Thus, when working on old switches or fixtures, test all wires for current. Even if you’ve flipped a fixture switch off, there could still be a hot conductor in the fixture outlet box.

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image476
Подпись: TIP
Подпись: Miscellaneous tools. From left:two slot-head screwdrivers, tapper (to cut threads in metal box holes), offset screwdriver, nut driver, utility knife, small pry bar/nail puller, plaster chisel, drywall saw, and hacksaw.

Подпись:

when an outlet is too distant. Cordless tools now have all the power you could want. Besides, they don’t need an extension cord and won’t electrocute you if you inadvertently drill or cut into a live wire. Cordless reciprocating saws can cut anything from plaster lath to studs; but use

a cordless jigsaw if you want to preserve the plaster around a cut-in box opening.

Miscellaneous tools...

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Design Considerations

Posted by on 18/ 11/ 15

For a waterway crossing, the designer must consider the backwater elevation and flow velocity for both the proposed and existing structures. It is recommended that the same hydraulic model be utilized for both the existing and proposed structure. Any increase in backwater elevation or stream velocity must be thoroughly analyzed and the upstream and downstream effects considered. For a grade separation structure the designer must consider both horizontal and vertical clearances. The shape of the replacement structure must be considered when determining the minimum clearances.

It is imperative that an accurate and complete survey of the existing structure be conducted...

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Orthogonal Transformation Techniques

Posted by on 18/ 11/ 15

The orthogonal transformation is an important tool for treating problems with correlated stochastic basic variables. The main objective of the transformation is to map correlated stochastic basic variables from their original space to a new domain in which they become uncorrelated. Hence the analysis is greatly simplified.

Orthogonal Transformation Techniques

Consider K multivariate stochastic basic variables X = (Xі, X2,, XK)t having a mean vector fj, x = (jx1, /г2 …, /гкУ and covariance matrix Cx as

 

011 012 013 021 °22 023

 

01K

02K

 

Cr =

 

0K1 Ok2 0K3

 

okk

 

in which oij = Cov(Xi, Xj), the covariance between stochastic basic variables Xi and Xj...

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STEP 8 Seal the Roof with Felt Paper

Posted by on 18/ 11/ 15

Now that the house has been framed and sheathed, its time to seal it from the elements.

As long as you are able to work safely on a roof, voucan cover it with rooting felt and shingles. It’s best if all the plumbing and beating vents are through the root before you install the felt.

If that isn’t possible, just make sure they’re installed before you begin shingling.

Roll out the felt paper

Felt paper, sometimes called tar paper or builder’s felt, is the first protective layer installed over roof sheathing. This material has evolved in a fashion similar to that of a candvbar. In the old davs, you could buv a good-size candy bar for a nickel. Today, you getamuch smaller bar at a higher price.

Similarly, the felt paper available today is much lighter, even though it’s sti. l sold as

1...

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Shapes and Materials

Posted by on 18/ 11/ 15
Shapes and Materials

Almost any size and shape of culvert can be utilized for the replacement of an existing bridge. However, reinforced concrete three – and four-sided box culverts, special shape reinforced concrete structures, metal box culverts, and long-span corrugated metal structures are particularly suited for this application. This is because they tend to have larger open-end areas with lower rises. General details on these structure types are given in Art. 5.6 and the structural design of these structures is given in Art. 5.8. Figures 5.42 and 5.43 show examples of reinforced concrete arches and a long-span corrugated steel culvert being used as bridge replacement structures.

Shapes and Materials

FIGURE 5.43 Corrugated steel culvert being used as a railroad overpass...

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PLACEMENT OF A MIXTURE

Posted by on 18/ 11/ 15

Corrections to mixture problems occurring during delivery of a mixture may be pos­sible up until the moment of placing the SMA. The moment the SMA layer appears behind the screed plate of a paver, the chances of improving the quality diminish to a minimum. After that time only compaction is possible; errors made during the design and manufacturing stages can no longer be corrected.

The vital elements of spreading an SMA layer include the following: [62]

10.3.1 image101
Layer Thickness

An SMA layer thickness should not be less than three times the maximum aggregate size in the mixture, and in principle, not greater than four times (higher ratios allow better compactability)...

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