Blog Archives

Innovations under the Han

Posted by on 24/ 11/ 15

The first imperial era was of great importance to the blossoming of China thanks to its cultural unity and construction of hydraulic infrastructure. Before moving on, we need to note the appearance of several other important innovations.

One innovation is the axial ship rudder (see Figure 8.10). We know that it appeared during this period from a terra-cotta scale model of a junk that dates from the 1st centu­ry AD and was discovered in a tomb at Canton.[421] At first, this was a movable rudder mounted on the stern of the hull. Later, it is attached to the sternpost of junks. The axial rudder is not adopted in the West until the 11th century.

A second innovation is the water wheel, appearing during the time of Wang Mang at the beginning of the 1st century AD...

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Primers and Paints*

Posted by on 24/ 11/ 15
Подпись: SURFACE PRIMER AND PAINT COMMENTS Drywall Unpainted Acrylic latex primer and paint Don't sand between coats Painted with oil-based semigloss or gloss Oil-based (alkyd) or latex To switch to latex: sand oil-based paint, vacuum, prime with acrylic latex primer Painted with latex Acrylic latex Sand lightly before first new coat; not needed thereafter Plaster Unpainted Acrylic latex primer and paint Plaster must be cured before painting; dilute primer coat Painted with oil-based semigloss or gloss Oil-based or latex To switch to latex: sand oil-based paint, vacuum, prime with acrylic latex primer Painted with latex Acrylic latex Lightly sand before painting Interior trim Doors, unpainted Oil-based primer and paint; semigloss finish Oil-based paint soaks into wood, dries harder, resists abrasion; sand between coats Unpainted Clear finishes, such as polyurethane and varnish Always seal bare wood or it will become grimy and dull Painted with oil-based semigloss or gloss Oil-based paint Sand between coats Painted with latex Acrylic latex Not as durable as oil-based paint Exterior Siding and trim, unpainted Acrylic latex primer and paint Latex stays flexible, allows some moisture migration Painted with oil-based semigloss or gloss Oil-based paint Unless you strip siding, stick with oil-based paint Painted with latex Acrylic latex * OiL-based here is synonymous with alkyd, now mentioned on most containers of paint and stain. Alkyds are synthetic resins that have largely replaced the traditional petroleum-oil base.

As you paint, be methodical so you won’t need to touch up missed areas. Paint top to bottom: Do ceilings, walls, trim and baseboards before doing doors and windows. Paint back to front: Many painters go to the deepest recess of a room— often, a closet—and work methodically toward a

Подпись:image909Подпись: When cutting corners or trim, slightly overlap the paint on the adjacent surface: 1/s in. to V4 in. Overlapping prevents unpainted spots, fills minor irregularities, and ultimately produces a cleaner line. It's also faster. Remember: You don't need to paint a perfectly straight cut-line till you apply the finish coat to the trim.Подпись: 1111Подпись: Use a hot-dog roller to fill those tight spaces over doors, around windows, inside cabinets, and the like.

door. Paint inside to out: If you start painting in the backs of built-ins and cabinets, your final brushstrokes on the outermost edges will be clean and crisp.

Once you’ve prepped the surfaces, masked off baseboards, and spread your drop cloths, it’s time to paint.

Painting the ceiling begins by using a brush to cut in a 2-in. to 3-in. border where the ceiling meets the walls and near all moldings...

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Install attic stairs

Posted by on 24/ 11/ 15

Some people like to install a folding staircase to give them access to attic space. A factory – made folding staircase doesn’t meet the code requirements for a regular stairway, so it’s not designed for everyday use. But if it is installed properly and used carefully, a folding staircase works quite well.

Most folding staircases consist of three lad­der sections that are hinged together and attached to a ceiling-mounted trapdoor. The door is hinged and held flush to the ceiling with springs. You pull on a cord to open the door and pull down the stairs. As the door swings down, you can unfold the two bottom sections of the staircase (see the top photo at left). The entire unit fits into a rough-framed attic-access hole between ceiling joists. The opening is typically 22/ in...

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SETTING A PREHUNG DOOR

Posted by on 24/ 11/ 15

Подпись: Nails Maintain a Ve-in. margin through between the jamb and Подпись: Take your time setting a prehung door. Make sure it opens and doses with ease. Shim and nail the jamb to the trimmers to hold it securely in place.SETTING A PREHUNG DOORПодпись: MAKE A BLOCK FOR THE BRACKET. Set the bracket that supports the bottom pivot of a bifold door on a small block. This block will later be covered with carpet. [Photo by Charles Miller, courtesy Fine Homebuilding magazine, ф The Taunton Press, Inc.]

the hinge and jamb and into the trimmer.

This step helps anchor the hinges and hinge – side jamb to the wall framing.

Throughout the process, continually check the door to see that it opens and closes with ease and that the jamb sides cross-sight, as described in the sidebar on p. 245. If a prob­lem develops, its best to find out along the way, rather than after the last nail has been driven home. If you’re driving nails by hand, use a nail set to set them below the surface of the wood so they can be hidden with putty.

Install bifold and bypass doors

Bifold doors work well in small areas, such as closets and laundries. They are supported by top and bottom pivots or guided by an over­head track...

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WOOD-SHINGLE VALLEY & HIP

Posted by on 24/ 11/ 15

DIRECTION OF

 

extend FIELD

 

WOOD-SHINGLE VALLEY & HIP

WOOD-SHINGLE RIDGE

Wood shakes are popular for their rustic look and their durability. They are made from the same materials as wood shingles, but they are split to achieve a taper instead of being sawn. Shakes may have split faces and sawn backs or be taper-split with both sides having a split surface. In either case, the split side is exposed to the weather because it has small smooth grooves parallel to the grain that channel rainwater down the surface of the shake. Because the weather side of the shake is split, not sawn, and because they are consider­ably thicker, shakes will last a great deal longer than wood shingles made of the same material.

Standard shakes are 18 in. or 24 in. long and come in heavy or medium thickness...

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Road Runoff Collection and Treatment

Posted by on 24/ 11/ 15

Where there are environmentally sensitive areas or high traffic flows, increasing the risks of accidents and generating contamination from wear, water flowing over the surface of the road and the embankment should be collected before it can soak into the ground in an uncontrolled manner. Water seeping through the earthworks and collected by a drainage layer has to be led, by virtue of a fall in the drainage layer and by shaping it, to collection points. At the collection point the water quality can be monitored and, according to the quality measured, it can be fed to a soakaway (Section 13.4.7) or piped away for treatment.

Water that arrives at an outlet from a drainage system may need treatment to bring the water quality to an acceptable level...

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Raising Heavy Timbers

Posted by on 24/ 11/ 15

Traditional timber framers will make all their bents ahead of time, and have them stacked in the proper order, waiting for the big day when plenty of help is gathered together for the raising. Lots of bodies wielding poles, as seen in Fig. 2.17, lift the bent to vertical. The poles can also act as temporary stops to aid during the lifting process. Someone — usually the boss — checks the bent for plumb, as diagonal bracing is fastened.

Oftentimes, professional timber framing contractors hire a crane for the big day.

My experience over thirty years has been to raise posts individually, brace them with temporary diagonal supports, and then to raise the girts or girders one at a time...

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Cold Climate Effects

Posted by on 24/ 11/ 15

It is a design objective that snowmelt and rainfall should have fast access to the side of the road and the drainage system. This avoids surface ice formation and skidding, but also protects the structure so that as little water as possible filters through to the pavement. Edges, kerbs, channels and runoff barriers must be kept clear by routine maintenance. Sufficient snow storage (and snowmelt) capacity on the road side must be included in the design. Dry structures and the road bed should be effected less by frost.

During spring-thaw there is considerable increase in the moisture of many un­bound materials. The magnitude of the spring-thaw weakening (on bearing capacity and slope stability) depends, very much, on the functioning of the drainage system.

Due to snow cover on the road side...

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SMA in an Intermediate Course

Posted by on 24/ 11/ 15

In some countries, SMA mixes have been applied in lower layers of the pavement structure. They are usually coarse-graded SMA mixes from 0/16 to 0/22 mm. Such solutions have been tested in the United States and recently in Germany, where they are called Splittmastixbinder (SMB) (Gartner et al., 2009; Schunemann, 2006). Because of the high binder contents, commonly a polymer modified binder with a stabilizer as well, the fatigue properties of the pavement are definitely better than those of conventional asphalt concrete. The application of a strong aggregate skel­eton increases the resistance to rutting.

In many cases, SMB 0/16 with a hard modified binder may be better than a conventional asphalt concrete layer...

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Suitable Soils

Posted by on 24/ 11/ 15

Most research to date has been done in homogeneous soils. However, there is no rea­son why the concept cannot be applied to heterogeneous soil masses if proper consid­eration of soil properties is made and rationally applied to the selection of nail length and spacing.

To be economical, soil nailed walls should be constructed in ground that can stand unsupported on a vertical or steeply sloped cut of 3 to 6 ft (1 to 2 m) for one to two days, and can maintain an open drill hole for a few hours. Soils considered favorable to soil nailing are as follows:

1. Naturally cohesive materials (silts and low-plasticity clays that are not prone to creep)

2. Naturally cemented sands and gravels

3. Weathered rock

4. Fine to medium, homogeneous sand with capillary cohesion of 60 to 100 lb/ft2 (2...

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