Blog Archives

Pavement Design and Climatic Effects

Posted by on 19/ 11/ 15

Most actual pavement design methods are based on the same principles. Linear elas­tic calculations are used to determine the stresses and strains in the pavement layers, under a reference traffic load, and then the calculated stresses and strains are com­pared with maximum allowable values, depending on the nature and characteristics of the pavement materials. Most usual design criteria are the following:

• For bituminous layers: a fatigue criterion, often limiting the tensile strain at the bottom of the bituminous layer to prevent upward cracking in thin bitumi­nous layers...

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Habitat Helps New Homeowners Continue Learning

Posted by on 19/ 11/ 15

PROVIDING A FAMILY with four walls and a roof is just the first step in helping them get established. Here at the Twin Cities’ affiliate, we also aim to equip families with knowl­edge, so that they become successful homeowners. Because Habitat fami­lies are first-time home buyers, most are unfamiliar with the basic mainte­nance, repair, and budgeting respon­sibilities that come with homeowner – ship. To bridge this information gap, we provide more than a dozen differ­ent classes.

Many classes emphasize that “an ounce of prevention” helps protect a family’s investment and reduces

long-term costs...

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Materials HOW TO ORDER VINYL SIDING

Posted by on 19/ 11/ 15

HORIZONTAL SIDING PANELS are usually 12 ft.

6 in. long, though some companies make longer panels. Siding is sold by the square, or the number of panels needed to cover 100 sq. ft. To estimate how many squares of siding you’ll need, calculate how many square feet of wall surface you need to cover, add 10% for waste, then divide by 100.

Order enough starter strips to go around the entire building; these typically come in 10-ft. lengths. You’ll also need trim for each inside and outside corner. You can order trim pieces that are the same color as the siding or use a contrasting color, as we did on this house.

If the windows didn’t come with an integral J-channel, or channel surround, then order enough

J-channel to cover the top and the sides of all the windows and doors...

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Generation of Random Numbers

Posted by on 19/ 11/ 15

The most commonly used techniques to generate a sequence of pseudorandom numbers are those that apply some form of recursive computation. In principle, such recursive formulas are based on calculating the residuals modulo of some integers of a linear transformation. The process of producing a random number sequence is completely deterministic. However, the generated sequence would appear to be uniformly distributed and independent.

Congruential methods for generating n random numbers are based on the fun­damental congruence relationship, which can be expressed as (Lehmer, 1951)

Xi+i = {aXi + c}(mod m) i = 1,2,…, n (6.1)

in which a is the multiplier, c is the increment, and m is an integer-valued modulus. The modulo notation (mod m) in Eq. (6.1) represents that

Xi+1 = aXi + c – mIi (6.2)

w...

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PLACEMENT OF ROADSIDE BARRIERS

Posted by on 19/ 11/ 15

Factors to consider in specifying the exact layout of a barrier at a given location include lateral offset from the edge of the traveled way, terrain effects, flare rate, and length of need. (See also Art. 6.10.)

6.7.1 Lateral Offset

Roadside barriers should generally be placed as far from the traveled way as condi­tions permit, to allow motorists the best chance of regaining control and to provide better sight distance. It is desirable to maintain a uniform clearance between traffic and roadside features such as bridge railings, retaining walls, and roadside barriers. The distance beyond which a roadside object will not be perceived as an obstacle and cause a motorist to reduce speed or change position is known as the shy line offset...

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WALL FLASHING

Posted by on 19/ 11/ 15

THE BEST HEAD FLASHING IS SOLDERED AT THE END SO THAT THE END PROFILE MATCHES THE SIDE PROFILE.

LOWER EDGE OF FLASHING ExTENDS PAST HEAD cASING AT LEvEL OF DRIP.

casing

 

FLASHING

 
WALL FLASHING

NOTE

THE DETAIL AT RIGHT IS PREFERRED TO THE DETAIL AT LEFT BECAUSE IT IS LESS SUSCEPTIBLE TO PHYSICAL DAMAGE.

 

WALL FLASHINGWALL FLASHING

WALL FLASHING

WALL FLASHINGПодпись: PAINT TENDS TO cLOG FLASHING DRIPS, BUT IT ALSO TENDS TO SEAL THE cRAcK BETWEEN FLASHING & THE MATERIAL THE FLASHING cOvERS. FLASHING SucH AS THIS SHOuLD BE USED ONLY AT LOCATIONS WITH MINIMAL EXPOSURE. Подпись:WALL FLASHING

FLASHING DRIPS

Soldered Head Flashing

TWO MORE practical solutions ARE TO cut THE FLASHING FLuSH WITH THE cASING, OR, BETTER, TO TRIM & FOLD THE FLASHING ON SITE, AS SHOWN BELOW.

SIDE OF cASING.

 

FOLD HORizONTAL PART OF FLASHING DOWN OvER SIDE OF cASING.

 

SuRFAcE OF SIDING TO BE APPLIED LATER.

 

Folded Head Flashing

 

WALL FLASHINGWALL FLASHINGWALL FLASHING

Section

WIND0W/D00R HEAD FLASHING

WIND0W/D00R HEAD FLASHING

At End of Flashing

SIDING PANE...

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STEP 4 COMPLETE VENTILATION AND ELECTRICAL WORK

Posted by on 19/ 11/ 15

Before you install the siding, soffits, and exterior trim, it’s important to resolve some ventilation and electrical details. For example, this house has a rectangular attic vent centered beneath the ridge in each gable-end wall. If you chose to sheathe the gable-end truss on the ground, this is the logical place to cut the hole for the vent.

If the hole hasn’t been cut yet, do so now, then install the vent (see the photo on p. 161).

Referring to your house plans, an electrician will be able to locate any outlet boxes that need to be installed in the exterior walls. Outdoor receptacles are placed at convenient locations; the same is true for outdoor lights.

This is also the time to cut the hole for the dryer vent. A standard dryer vent requires a 4-in...

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Copyright © 2006 by The McGraw-Hill Companies, Inc. Click here for terms of use

Posted by on 19/ 11/ 15

As noted previously, the accuracy of the model output statistics and probabil­ity distribution (e. g., probability that a specified safety level will be exceeded) obtained from Monte Carlo simulation is a function of the number of simu­lations performed. For models or problems with a large number of uncertain basic variables and for which low probabilities (<0.1) are of interest, tens of thousands of simulations may be required. Rules for determining the number of simulations required for convergence are not available, and thus replication of the Monte Carlo simulation runs for a given number of simulations is the only way to check convergence (Melching, 1995). Cheng et al...

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SELECTION OF ROADSIDE BARRIERS

Posted by on 19/ 11/ 15

In most cases, the selection of a roadside barrier should be made on the basis of the system that will provide the required degree of shielding at the lowest cost. The lowest cost should be based on a life-cycle cost analysis, considering initial and maintenance costs

Подпись: AASHTO designation: Post Type: Beam Type: Nominal Barrier Height:

SELECTION OF ROADSIDE BARRIERS Подпись: Й ;r 7" 3 4 88" 4"3 7" 'I —r - End of timber rail 1’/; 1V dia. holes for 3/8" dia. holes (typ.) 1 I lag screws (typ.) 8 Чч . - . ' : 5 : -тп 14" Steel plate " %" thickness - 8 spaces at 11" TT 14" STEEL RAIL (typ.)

None

10 in x 12 in x 7 in rough-sawn timber 6 in x 10 in timber with steel plate backing 27 in

FIGURE 6.20 Steel-backed wood-rail roadside barrier. Conversions: 1 in = 25.4 mm, 1 ft = 0.305 m. (From Roadside Design Guide, AASHTO, Washington, D. C., 2002 and 2006, with permission) and project life. Factors that should be considered in making the selection are summarized in Table 6.3. The most important decision is the performance level required...

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