Blog Archives

WOOD CONSTRUCTION CONNECTORS

Posted by on 13/ 11/ 15

Wood construction connectors are commonly called Simpson™ Strong-Ties™ after the company that popularized them. For a complete overview of available connectors from Simpson, go to www. strongtie. com. Professionals swear by these ingenious connectors for three main reasons.

►They offer wood-to-wood connections superior to most traditional construction methods. For example, unlike toenailing, metal connectors are unlikely to split lumber ends or loosen under stress. These galvanized steel connectors are strong and durable.

►They greatly strengthen joints against earthquakes, high winds, and other racking forces. They can tie rafters to walls, walls to floor platforms, and the substructure to its foundation.

►Most can be attached to existing framing, a great boon to renovators, and in ma...

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Syria-Palestine in the IInd millennium BC

Posted by on 13/ 11/ 15

The city of Ugarit, on the northern Syrian coast (several kilometers to the north of the present-day Lattaquieh), has been occupied since very early times. It served as a mar­itime port for trade with Cyprus and Crete in the context of commerce among Mesopotamia, Mari, Aleppo, Ebla and the Mediterranean, and then as a port of the Hittite Empire of Anatolia. The city knew a period of great prosperity from the IInd mil­lennium BC until its final destruction in 1200 BC by the Sea People. The city is built on high ground, using wells for its primary water supply. As at Mari, rainwater is cap­tured on terraces and brought through gutters and vertical drops to the cisterns of hous – es.[72] The city is surrounded by two small temporary watercourses, the nahr ed-Delbe and the nahr Chbayye, on ...

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Variance, standard deviation, and coefficient of variation

Posted by on 13/ 11/ 15

The spreading of a random variable over its range is measured by the variance, which is defined for the continuous case as

/

TO

(X – fZx)2 fx(x) dx (2.36)

-TO

The variance is the second-order central moment. The positive square root of the variance is called the standard deviation ax, which is often used as a measure of the degree of uncertainty associated with a random variable.

The standard deviation has the same units as the random variable. To com­pare the degree of uncertainty of two random variables with different units, a dimensionless measure ^x = ax/^x, called the coefficient of variation, is useful. By its definition, the coefficient of variation indicates the variation of a random variable relative to its mean...

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Curbs

Posted by on 13/ 11/ 15

The type of curb and its location affect driver behavior patterns, which, in turn, affect the safety and utility of a road or street. Curbs, or curbs and gutters, are used mainly in urban areas. They should be used with caution where design speeds exceed 40 mi/h (64 km/h). Following are various reasons for justifying the use of curbs, or curbs and gutters:

• Where required for drainage

• Where needed for channelization, delineation, control of access, or other means of improving traffic flow and safety

• To control parking where applicable

Types of Curb. There are two general categories of curbs: barrier curbs and mount­able curbs. Barrier curbs are relatively high [6 in (0.15 m) or more] and steep-faced. Mountable curbs are 6 in (0...

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Interchange Elements

Posted by on 13/ 11/ 15

Cross-section information pertaining to interchange elements, such as ramps and directional roadways, is given in Fig. 2.26. This information includes pavement and shoulder dimensions for acceleration-deceleration lanes, one – and two-lane directional roadways, and medians between adjacent ramps. Notice that for a single-lane ramp, the shoulder and guiderail offset distances are greater on the driver’s right-hand side than on the left. This is to provide more width for drivers to pull over in emergencies and to allow people a better opportunity to go around disabled vehicles.

2.3.2 Medians

A median is a desirable element on all streets or roads with four or more lanes...

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Grading and Side Slopes

Posted by on 13/ 11/ 15

This section is concerned with the design of the slopes, ditches, parallel channels, and interchange grading. It incorporates into the roadside design the concepts of vehicular safety developed through dynamic testing. Designers are urged to consider flat foreslopes and backslopes, wide gentle ditch sections, and elimination of barriers.

Slopes. Several combinations of slopes and ditch sections may be used in the grading of a project. Details and use of these combinations are discussed in subsequent paragraphs. In general, slopes should be made as flat as possible to minimize the necessity for barrier protection and to maximize the opportunity for a driver to recover

TABLE 2.24 Recommended Pavement Widening on Horizontal Curves, ft, for WB-50 Design Vehicles

Degree of curve

Pav...

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Roadway Criteria

Posted by on 13/ 11/ 15

Lane Widths and Transitions. When considering the physical characteristics of cross sections, the values selected will depend on location (rural or urban), speed, traffic volumes, functional classification, and, in urban areas, the type of adjacent development. Tables 2.21, 2.22, and 2.23 provide values currently used in Ohio. Lane width is dependent on design speed, especially in rural areas. Widths may be as narrow as 9 ft (2.74 m) for a local, low-volume road. In urban areas, lane widths can be as narrow as 10 ft (3.05 m), if the road is primarily a residential street. The maximum lane width is generally accepted to be 12 ft (3.66 m) in all locales.

In some cases it may be necessary to widen the pavement on sharp curves to accommodate off-tracking of larger vehicles. Table 2...

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The Soil Water Characteristic Curve (SWCC)

Posted by on 13/ 11/ 15

The soil water characteristic curve (SWCC) provides the relationship between the matric suction and water content for a given soil. In fact, calling the curve “character­istic” is something of a misnomer as the relationship is not solely a function of the soil type, but varies with (for example) temperature, pressure and pore water chemistry. A typical soil water characteristic curve for sand and clay can be seen in Fig. 2.9a.

Подпись: Capillary pressure Подпись: Capillary pressure Moisture content, 0 [% by vol]

Figure 2.9 shows clearly that, even at very high matric suctions (capillary pres­sures), all the water cannot be removed from the soil...

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Determine the sill’s position

Posted by on 13/ 11/ 15

Depending on what you find after measuring the foundation, you may need to adjust the sill’s position using some of the techniques explained in the sidebar on p. 55. The sill plates are often bolted flush to the outside of the foundation, but there are variations you may want to consider (see the illustration on p. 58). For example, when the walls will be sheathed with ‘/i-in. plywood or OSB, it’s best to hold the plates Vi in. inside the founda­tion. This puts the sheathing flush with the foundation and allows the siding to lap down over the concrete.

The sills must be installed along snapped layout lines on top of the foundation walls. (If

Подпись: This side of the foundation is 1/2 in. lower than the other side.

USING A WATER LEVEL

A simple water level can be used to check the foundation for level. These are available at home improvement centers...

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Choosing a foundation

Posted by on 13/ 11/ 15

Each foundation system has many variations, and it is important to select the one best suited to the climate, the soil type, the site, and the building program. With all foundations, you should investigate the local soil type. Soil types, along with their bearing capacities, are often described in local soil profiles based on informa­tion from the U. S. Geological Survey (USGS). If there is any question about matching a foundation system to the soil or to the topography of the site, consult a soil or structural engineer before construction begins. This small investment may save thousands of dollars in future repair bills.

design checklist

Because the foundation is so important to the longevity of the building and because it is so difficult to repair, it is wise to be conservative in its d...

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