Blog Archives

Exteriors

Posted by on 15/ 11/ 15

The exterior і multi­

layered membrane, weatherproofing the house much the way a roof does. In addition to protect­ing underlying elements from damage by sun and wind, the exterior intercepts and directs water away from the underlying sheathing and fram­ing. The visible exterior layer consists of siding and trim. Beneath the siding, ideally, is either building paper or plastic housewrap, which is relatively water repellent. In addition, flashings seal transitions from one material to another or redirect water around potential dams, such as window and door headers, vent fans, and outdoor outlets. Finally, various sealants fill gaps, adhere materials, or cut air infiltration. Of course, win­dows and doors are exterior elements, too...

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BRIDGE ENGINEERING

Posted by on 15/ 11/ 15

Walter J. Jestings, PE.

Formerly, Bridge Engineer
Parsons Brinckerhoff, Quade & Douglas, Inc.
Atlanta, Georgia

Mahir Sen, P. E.

Professional Associate
PB Americas, Inc.

Newark, New Jersey

This chapter is directed at practical issues of importance in the design and rehabilita­tion of traditional bridge types for short and medium spans. Subjects addressed include characteristics of various bridge types, considerations in their selection, and suggestions for economical design; materials for bridges and bridge decks; bridge deck design, construction, and maintenance; deflection and expansion joints; and bridge bearings. The issues are addressed from a general viewpoint, with the emphasis on what is generally done and why. Detailed design methods are available in other publications. (See R. L...

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LIFE CYCLE COST ANALYSIS OF PAVEMENTS

Posted by on 15/ 11/ 15

It is seldom readily apparent which is the most economical rehabilitation method for a particular pavement. Each rehabilitation strategy has unique initial construction costs, performance expectations, and future maintenance needs. What is most economical for one pavement may not be for another. Local costs may differ from one location to another, and material performance expectations may be different from region to region. The only rational way to compare one rehabilitation strategy and another is to perform an economic analysis of the alternative strategies. The method used for such a study is the life cycle cost analysis (see Chap. 10).

It is not good practice to compare a minor pavement rehabilitation strategy and a complete pavement replacement strategy...

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Microsurfacing

Posted by on 15/ 11/ 15

Microsurfacing is the application of a thin cold-applied paving mixture composed of polymer-modified asphalt emulsion, 100 percent crushed aggregate, mineral filler, water, and other additives. A self-propelled continuous loading machine or a truck-mounted machine is used to proportion and mix the materials and apply the mixture to the pave­ment surface. Microsurfacing is used to retard raveling and oxidation, fill ruts, reduce the intrusion of water, improve surface friction, and remove minor surface irregularities.

The following conditions should be given careful consideration prior to microsurfacing:

• Localized wheel track cracking or edge cracking (see Figs. 3.57 and 3.58) should be repaired full depth.

• Any potholes must be repaired full depth.

• Areas which exhibit debonding m...

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INSTALLING AND FLASHING SKYLIGHTS

Posted by on 15/ 11/ 15

Follow the manufacturer’s instructions when installing and flashing your skylight, so the war­ranty will be honored should the unit leak. Installations shown are fairly typical.

Screw the mounting brackets to the sides of the skylight curb; most brackets are adjustable. Then, with one worker on the roof and one in the attic, pass the skylight out through the opening. As the worker outside raises or lowers the brack­ets till the top and bottom of the unit are level, the worker inside centers the unit in the opening.

image260

Different skylight, same installer. Here, he frames out the lightwell before cutting a hole in the ceiling because it was raining...

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The Cretan cities and palaces: urban hydraulics brought to perfec­tion

Posted by on 15/ 11/ 15

Crete was inhabited by migration from Anatolia, probably at the end of the VIIth millen­nium BC. Its more highly developed civilization, the Minoan, dates from about 2100 BC. This maritime empire was apparently a peaceful one, since neither palaces nor cities were fortified – and this despite the threatening face of the monster that the legendary king Minos kept in his labyrinth according to the Greek legends of Theseus and Minotaur.[138] A creative and sophisticated urban and palatial architecture characterizes this civilization. The Egyptians know the Cretans as the Keftious, and Mesopotamians know them as the Kaptaras...

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Stage 4: Determining an Initial Content of Binder

Posted by on 15/ 11/ 15

The minimum content of binder in an SMA has been fixed at 6.0% (m/m), but a slightly higher quantity of binder in a mixture is advised. This is intended to provide protection from exceeding the lower production limit when producing the SMA.

To begin, an initial trial quantity of binder in mixtures should be adopted (the same for each of the three mixtures). The trial binder quantity should be adjusted depending on the density of the aggregate mixes. The reference density of an aggre­gate mix is typically 2.75 g/cm3; if the density differs, the quantity of binder should be adjusted in accordance with this rule: each change of density by 0.05 g/cm3 cor­responds to an adjustment of binder by 0.1% (m/m). For densities less than 2.75, and for densities greater than 2...

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Hydrologic Frequency Analysis

Posted by on 15/ 11/ 15

One of the basic questions in many hydrosystems infrastructural designs that an engineer must answer is, “What should be the capacity or size of a system?” The planning goal is not to eliminate all hydro-hazards but to reduce the fre­quency of their occurrences and thus the resulting damage. If such planning is to be correct, the probabilities of flooding must be evaluated correctly. The prob­lem is made more complex because in many cases the “input” is controlled by nature rather than by humans. For example, variations in the amount, timing, and spatial distribution of precipitation are the underlying reasons for the need for probabilistic approaches for many civil and environmental engineer­ing projects...

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Dry-Rodded Method

Posted by on 15/ 11/ 15

The dry-rodded method has been standardized in AASHTO T 19-00, where its thor­ough description has been included. It is recommended to perform two tests per sample and use the average value. The following gives a short outline of the equip­ment used and the modus operandi.

The equipment needed includes a balance, a steel tamping rod (rammer), a cylin­drical metal measure, a shovel, glass calibration plate (Figure 7.4), and grease or thick glycerin. The sample of aggregate is dried in an oven to a constant mass. The sample should be about 125-200% of an amount that fits in the container. The cylin­drical measure is calibrated by determining the volume using water and the glass plate (Figures 7.5 and 7...

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STEP 4 MARK THE PLATES

Posted by on 15/ 11/ 15

Building walls is like baking a cake. Success depends on having all the right ingredients. When you mark the plates, you’re setting the exact locations for all of the headers, cripples, studs, corners, and wall intersections associated with each wall in the house.

Подпись: їм їм їм їм їм и їм їм їм їм їм їм їм и їм їм їм їм їм їм їм и їм їм їм їм їм їм їм и їм їм їм їм їм їм и їм їм їм їм їм їм їм и їм їм їм їм їм їм їм и їм їм їм їм і MARKING CORNERS AND CHANNELS STEP 4 MARK THE PLATESSTEP 4 MARK THE PLATESПодпись: The fastest, most accurate way to mark corners and channels is with a tool the same width as the butt walls. In less than a minute, you can cut and nail together such a tool from scrap. Select two pieces of 2x stock about 10 in. long. Turn one piece on end and place the second piece flat against it to form a "T." With the second piece protruding over the first by 3 in., nail the two together with 16d nails.

Mark corners and channels first

When marking up each plate, start with the loca­tions of corners and wall intersections, which are referred to as channels or tees (see the top illustra­tion at right). As we’ll see shortly, corners and channels require extra studs so that the walls can be properly nailed together once they are raised. The extra studs also provide backing for drywall on the inside and siding on the outside. Use a channel marker to mark corners and channels on the plates...

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