Blog Archives

A dam to protect Tiryns

Posted by on 16/ 11/ 15

A catastrophe strikes the city of Tiryns toward the end of the Mycenaen civilization. The city is located on an alluvial plain about one kilometer from the sea; the palace is 24 m above sea level, on a limestone hill. The city itself is at the foot of the palace, to the east and south. The watercourse along which the city is located, the Lakissa, leaves the mountains on a steep slope of nearly 15 m/km as dictated by the local topography.

Levees normally protect the city from the caprices of the river. But in about 1200 BC, at essentially the same time that the nearby city of Mycenae and its palaces were destroyed and burned, an exceptional event occurred...

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Interior trim

Posted by on 16/ 11/ 15

Interior trim

might see on a Victorian-style house. Because I want the trim to look good,

I use hot-dipped galvanized, stainless – steel, or aluminum finish nails when installing exterior casing so that the nails won’t rust and stain the wood.

Interior casing goes around interior doors and windows and hides the gap between the drywall and doorjambs or window frame (see the drawing above). The joint where the side piece meets the casing at the top is usually a 45° miter.

Flat, rectangular casings that are wider and more affected by shrinking/swelling cycles are often cut square and butted together. Use finish nails to attach cas­ing so they can be set below the surface and covered with wood putty.

The stool (sometimes called a sill) is the flat piece of trim installed at the bottom of a window (a perf...

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STEP 6 RAISE THE WALLS

Posted by on 16/ 11/ 15

Подпись:

Подпись: 1. To mark the cut line, position the brace diagonally across the wall section from the bottom plate to the double top plate, and then pencil a line along one edge of every framing member the brace crosses. [Photo © Larry Haun] STEP 6 RAISE THE WALLS

As with barn raisings of yore, it takes a few warm bodies to raise framed walls. Let one per­son be the team leader and encourage everyone

Подпись: The first wall goes up! Make sure you have enough help when you're ready to raise the walls. Have one person take charge, and get everyone to lift in unison. [Photo by HFHI/Will Crocker] When you re­move the tem­porary blocks nailed to the rim joist, be sure to pull the nails or bend them over so that no one gets a nail in the foot!

Подпись: Temporary braces are important. After raising a wall, make sure it is braced securely with 2x lumber that extends diagonally from the rim joist or the floor to the top of a stud in the wall. Secure bracing eliminates the serious injuries that can result from a falling wall. These braces also help keep walls plumb, straight, and ready for roof trusses.Подпись: Nailing the bottom plate is best done when one worker nails while others steady the wall. The short 2x4s nailed to the rim joist prevent the bottom plate from sliding off the floor when the wall is raised.

to work together (see the photo above). Remind people to lift with their legs, not with their backs. In many areas, builders put a heavy bead of caulk or a roll of foam (polystyrene) on the floor or slab under the bottom plate before rais­ing a wall. This helps keep out cold air as well as any bugs that may want to migrate inside...

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Nail on the double top plate

Posted by on 16/ 11/ 15

In some parts of the country, carpenters raise the walls before cutting and nailing on the double top plate. In my opinion, the time to nail on the double top plate is now—while the wall is still flat on the floor. Otherwise, you will have to use a ladder. The top plate is an impor­tant structural member. It ties the entire frame together. Without it, severe lateral stress from an

earthquake or high winds could easily rip apart a building. If you frame with a single top plate, secure them together with metal plate straps.

On a 2×4 butt wall, the double top plate ex­tends beyond the top plate a bit less than ЗУ2 in. (cut it /4 in. short—about 3/4 in.—to make sure it doesn’t protrude beyond the through wall), so that it can tie into the notch in the double top plate of a through wall...

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All You Need to Know about Spray Foam

Posted by on 16/ 11/ 15

■ BY ROB YAGID

I

recently spent a day pulling wire with a friend who’s an electrician in New York. Late in the afternoon, our conversation turned to a client and friend of his who was seeking advice about insulating her new home. The topic caught the interest of some other guys on site, most from differ­ent trades, who gathered around and offered their opinions on which material she should use. After a brief debate, everyone seemed confident that spray foam would yield the best performance. That was until I threw out the question, "Which type?" Sure, they all knew there were two types of spray polyure­thane foam, open cell and closed cell, but no one knew enough about them to step up and defend the use of one over the other. The truth is, neither did I.

Spray polyurethane-foam manu...

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BUILDING CORNERS AND CHANNELS

Posted by on 16/ 11/ 15

Like headers, outside corners and channels can be built in a number of different ways, and preferences tend to be regional. The most common constructions are shown in the illustration below. A two-stud outside corner works well in most cases, but if you are planning to install clapboard or fiber-cement siding directly to the studs (with no exterior sheathing), you’ll need more backing at the outside corners. A blocked-up corner provides more backing and mak es good use of 2x offcuts. In addition, all of these outside cor­ner configurations provide backing on the inside of the wall for drywall or other wallboard.

Channels (sometimes called tees) are most easily made with a flat stud or blocks nailed between two regular studs. I place a crowned or knot-filled stud between two good studs...

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Analytical Approaches

Posted by on 16/ 11/ 15
Analytical Approaches Подпись: в Подпись: (3.5)

An alternative to the graphic technique is to estimate the statistical parameters of a distribution from the sample data (refer to Sec. 3.6). Then the distribution model can be used to solve for the variate value corresponding to any desired return period or probability as

in which F-1(e) is the inverse cumulative distribution function with the model parameter vector в. Equation (3.5) can be applied when the inverse distribu­tion function forms are analytically amenable, such as for the Gumbel, gener­alized extreme value, generalized logistic, and generalized Pareto distributions (see Sec. 2.6.6).

Example 3.2 Consider that the annual maximum floods follow a lognormal distribu­tion with a mean of 490 ft3/s and a standard deviation of 80 ft3/s...

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Fine Aggregate and Filler

Posted by on 16/ 11/ 15

According to concept of van de Ven et al. (2003), an SMA mixture probably has no real stone skeleton immediately after compaction. A real skeleton in SMA is cre­ated during service under the effects of traffic and climatic loading when sand and filler grains between the coarse aggregates (skeleton) may be crushed or moved. Accordingly, at the design stage, the content of fine aggregate and filler must be determined.

Cause-and-effect relationships between the filler and the fine aggregate (crushed sand) have not been determined in a design method. Some Dutch research into this has led to establishing the optimal relationship between those elements...

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Drainage and land improvement in the Mycenaen civilization

Posted by on 16/ 11/ 15

Many of the regions of Peloponnese or Attica are karsitic. Entire rivers disappear into abysses or caverns (called catavothres in Greek), only to reappear at some distant point.

When the subterranean cavities fill up or are blocked, for example after earthquakes, water can accumulate in marshes and lakes, the water level varying from season to sea­son and from one period to the next. Strabo describes these phenomena:

“Some of these plains are marshy, since rivers spread out over them, though other rivers fall into them and later find a way out; other plains are dried up, and on account of their fertility are tilled in all kinds of ways...

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Port development at Pylos

Posted by on 16/ 11/ 15

Between 1400 and 1200 BC, Achean shipping dominates long-distance commerce in the eastern Mediterranean, extending to Sicily, and perhaps even as far as to Spain. The ports of Antiquity are often developed in natural bays (that do not always provide good shelter), or in river mouths.

Recently, a detailed study of the Pylos region has made it possible to reconstitute the development of an artificial port.[150] This port was created by excavating a closed basin into marine sediments, and linking it to the sea through a channel (Figure 4.8, 4.9). The sinuous path of the channel keeps ocean swells from entering the port itself.

The port would rapidly have become unusable without additional engineering efforts, either due to silting-in of the basin itself, or by the blocking of the entrance cha...

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