Blog Archives

Fat Spots of Mastic with Segregation

Posted by on 20/ 11/ 15

An area with a definite shortage of mastic adjacent to the fat spot (visibly porous) is a clear sign that this is a case of an SMA segregation—namely, separating the coarse aggregates from the mastic. If the quantities of all the ingredients have been properly selected, the high accumulation of one component in one location will result in a reduced quantity of that component in another. When an excess of mastic (fat spot) appears somewhere, the coarse aggregate content rises elsewhere, so the total sum of the components remains constant. Figure 11.2 presents a classic fat spot in a segre­gated SMA mixture. Figure 11.3 shows the difference between fat spot and adjacent porous section and a close-up of the mastic-rich area.

It is worth emphasizing that such segregation may happen for one ...

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STEP 3 Install the Foundation and Floor Framing

Posted by on 20/ 11/ 15

Concrete piers and FT posts work well for supporting the front of the porch. In some areas, code may require that concrete porch piers be set on concrete footings, so check with your building department. For a deck that’s 6 ft. wide by 16 ft. long, set three piers (16 in. square by 12 in. deep), one on each corner and one in the middle (see the top illustration at right). Shorter decks can be built with a concrete pier on each corner; longer decks need more piers. I like to use precast piers that have steel post anchors set in them. The anchors hold the posts in place and resist wind uplift. Check your house plans for porch width and set the piers so they are inline with the ledger board and square with the building.

Next, measure the length for the posts that will extend from the piers ...

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MEPDG

Posted by on 20/ 11/ 15

The above methods define stiffness as a function of stress alone. Full incorporation of the effects of moisture (as a pressure or suction) should necessitate use of an effective stress framework (see Section 9.5). However a more simple approach, at least in principle, is to adjust the stiffness value calculated by one of the above rela­tionships using a factor that is dependent on the moisture (and, perhaps, other) con­dition. The AASHTO ‘Mechanistic-Empirical Pavement Design Guide’ (MEPDG) takes this approach, though it’s attention to many details makes the implementation rather complex (ARA, 2004)...

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Drilling and Notching Studs and Joists

Posted by on 20/ 11/ 15

Подпись: Notching and Drilling LimitsПодпись: JOISTS

It’s often necessary to notch or drill framing to run supply and waste pipes.

If you comply with code guidelines, given in "Maximum Sizes for Holes and Notches," on p. 287, you’ll avoid weakening the struc­ture. Although that table is based on the following rules of thumb, remember that local building codes have the final say.

Joists

You may drill holes along the entire span of a joist, provided the holes are at least 2 in. from the joist’s edge and don’t exceed one – third of the joist’s depth. Notches are not
allowed in the middle third of a joist span. Otherwise, notches are allowed if they don’t exceed one-sixth of the joist’s depth.

Studs

Drilled holes must be at least 78 in. from the stud’s edge. Ideally, holes should be centered in the stud...

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EXAMPLES FROM THE DEMONSTRATION PROJECTS

Posted by on 20/ 11/ 15

Подпись: Boise, IdahoEXAMPLES FROM THE DEMONSTRATION PROJECTSПодпись: Lincoln, NebraskaTypical Boise streets have sidewalks on both sides. At Lakewood Meadows, the city permitted elimination of sidewalks on one side of the sub­division’s streets and around T – turnarounds. One higher-order collector street was required to have sidewalks on both sides, but a sidewalk on one side only was allowed for a high-volume arterial street. Walkways were provided in common areas and between T – turnarounds.

The builder estimated that 2,696 additional linear feet of sidewalk would have been required to comply with existing Boise standards. Construction costs were decreased by $8,088, a per-unit reduction of $216.

Existing Lincoln standards call for 4- foot wide sidewalks on both sides of all residential streets...

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Generating multivariate random variates subject to linear constraints

Posted by on 20/ 11/ 15

Procedures described in Sec. 6.5.2 are for generating multivariate normal (Gaussian) random variables without imposing constraints or restriction on the values of variates. The procedures under this category are also called uncon­ditional (or nonconditional) simulation (Borgman and Faucette, 1993; Chiles and Delfiner, 1999). In hydrosystems modeling, random variables often exist for which, in addition to their statistical correlation, they are physically related in certain functional forms. In particular, this section describes the procedures for generating multivariate Gaussian random variates that must satisfy pre­scribed linear relationships. An example is the use of unit hydrograph model for estimating design runoff based on a design rainfall excess hyetograph...

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Framing for Toilets and Tubs

Posted by on 20/ 11/ 15

You may need to cut through joists to accom­modate the standard 4 by 3 closet bend beneath a toilet or the drain assembly under a standard tub. In that event, reinforce both ends of sev­ered joists with doubled headers attached with double-joist hangers. This beefed-up framing provides a solid base for the toilet as well.

If joists are exposed, you can also add joists or blocking to optimize support.

Toilets

A minimum 6-in. by 6-in. opening provides enough room to install a no-hub closet bend made of cast iron (41/2 in. outer diameter) or plastic (З1/? in. outer diameter). The center of the toilet drain should be 12 in. from a finish wall or 1232 in. from rough framing...

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CLEARANCES RELATED TO WATER CLOSETS

Posted by on 20/ 11/ 15

Подпись:Let’s talk about clearances related to water closets. There’s not a lot to go over, so this can move along quickly. Remember that we are talking about standard plumbing fixtures here, not handicap fixtures. The minimum distance required from the cen­ter of a toilet drain to any obstruction on either side is 15 inches. Measuring from the front edge of a toilet to the nearest obstruction must prove a mini­mum of 18 inches of clear space. When toilets are installed in privacy stalls, you must make sure that the compartments are at least 30 inches wide and at least 60 inches deep. That’s all there is to a typical toilet layout (Fig. 10.7).

URINALS

urinals must have a minimum distance of 15 inches from the center of the drain to the nearest obstruction on either side...

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Sign-Support Selection

Posted by on 20/ 11/ 15

The only types of sign-support systems that should be used are those that have been approved for use by the FHWA. The following concerns should be addressed in the selection of an appropriate single-sign-support system:

• The specifications for support size provided by many states provide information on the maximum sign panel area to be mounted on the support. The shape of the sign as well as the area should be considered when determining the type and number of supports required. For example, a 5-ft X 2-ft (1525-mm X 610-mm) guide sign will have less area than a 4-ft X 4-ft (1220-mm X 1220-mm) warning sign. The wide dimension of the guide sign, however, will result in excessive vibration from wind loads if it is placed on a single sign support without bracing...

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Advanced Pavement Analysis

Posted by on 20/ 11/ 15

The behaviour of unbound granular materials in a pavement structure is stress – dependent. For that reason the linear elastic model is not very suitable. A non-linear elastic model, with an elastic modulus varying with the stress and strain level is, therefore, needed.

For isotropic materials, moduli depend only on two stress invariants1: the mean stress level, p, and the deviatoric stress, q, which are given in the general, as well as the axi-symmetric case (cylindrical state of stress with o1 = oaxial and o2 = o3 =

oradial as:

General

P = T

q = 2 0ij0ij with 0ij = 0ij pSij

In a similar way strain invariants can be introduced. The volumetric strain ev and the deviatoric strain eq, are defined as:

An invariant has the same value regardless of the orientation at which it is measured.

(9.3)

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