Blog Archives

Edge Sealing

Posted by on 20/ 11/ 15

In regard to edge sealing, the following reasonable solution definitely extends the durability of a pavement and has been adopted in German practice (Milster et al., 2004):

• An extra layer of tack coat (of hot binder) is placed on the edges of pavement (between the layers), minimum 10 cm wide.

• A binder layer, minimum 2 mm thick, on a side surface of all layers, is applied (to achieve such a layer of binder, the tack coating usually needs to be repeated, or a hot sealant 2 mm thick needs to be applied in one work­ing cycle).

This sealing is aimed at protecting the pavement against water infiltration between layers and inside them.

10.6 OPENING TO TRAFFIC

Before opening up a road section with a new SMA layer to traffic, one should be sure that it has sufficiently cooled...

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Tool Talk TOOLS FOR VINYL SIDING

Posted by on 20/ 11/ 15

Tool Talk TOOLS FOR VINYL SIDINGA LONG, FLAT work surface is essential for vinyl siding and sheet-metal work. A couple of 2×12 boards on sawhorses work fine. For precise 90-degree-angle cuts and angled rake cuts, I suggest making a cutting jig for a circular saw (see the photo at bottom left). The jig, which sits on a long worktable, is essentially a wooden cradle that guides the base of the circular saw. The cradle can be positioned at a right angle, or at

Tool Talk TOOLS FOR VINYL SIDINGother angles, to the siding.

Use both right – and left-handed aviation snips to make straight and curved cutouts (see the photo at top right); tinsnips are also helpful...

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Gritting Execution

Posted by on 20/ 11/ 15

Grit is spread on an hot SMA mixture using one of the two following techniques:

• With a gritter installed on a roller, during the first pass of the roller there is no gritting, but during the second pass the gritting is turned on. One should remember to grit in one direction of roller movement, and to not grit when returning; when using that technique, grit particles are pressed into the hot SMA mixture (Figure 10.15).

• With a self-propelled gritter, gritting starts after rolling the layer down with the rollers, when the SMA is still hot enough and prior to the last pass of the roller. This method is seldom used.

Remember that the quantity of grit per square meter has been established for a given machine (a gritter) and for a specific passing speed. Any change to the speed

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FIGURE...

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Hold-Downs

Posted by on 20/ 11/ 15

Hold-downs are connections commonly used for foundations, wall-to-wall connections, wall-to – concrete connections, and wall or floor-to-drag strut. Hold-downs are also called anchor downs and tie-downs. They can be difficult to install, but if you plan ahead and install as you go, the job is more manageable. Hold-downs that attach walls to the concrete foundation are typically attached to bolts already in the concrete. These bolts are generally set in place by the foundation crew. Sometimes they won’t be set in the right place.

You will want to locate the hold-down as close to the end of the shear wall as possible. If the bolt is already in the concrete, you will have to locate a hold-down on either side of the bolt...

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Fastening the Girt to the Top of the Posts

Posted by on 20/ 11/ 15

Before attempting to lift a heavy girt (or girding beam) to the top of posts, make sure that the posts are vertically plumb — check two adjacent sides with the plumbing bubble on your level — and that all the posts are supported with sturdy bracing, as already discussed. Make sure that the posts are all the same — and the correct — height (see Post Height earlier in this chapter), and that their tops are square, which, in this case, translates to flat.

Based on your plan, the girts might be supported by two, three, or even more posts. A post at each end supports the 16-foot-long (4.9-meter-long) eight-by – eight girts in our garage, with a third post supporting the middle. The posts need to be the same height so that the girt will rest nicely on all three.

Russell Pray, a contracto...

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Gamma distribution

Posted by on 20/ 11/ 15

The gamma distribution is used frequently in the statistical analysis of hydro­logic data. For example, Pearson type III and log-Pearson type III distributions used in the flood frequency analysis are members of the gamma distribution family. It is a very versatile distribution the PDF of which can take many forms (see Fig. 2.20). The PDF of a two-parameter gamma random variable, denoted by X ~ GAM(a, в), is given by Eq. (2.72). The standard gamma PDF involving one-parameter a can be derived using variable transformation by letting

Y = X/в. The PDF of the standard gamma random variable Y, denoted by

Y ~ GAM(a), is shown in Eq. (2.78)...

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Placement of Crash Cushions

Posted by on 20/ 11/ 15

For proper performance, crash cushions should be placed on level terrain with a clear path between the roadway and the attenuator so the vehicle can strike at normal height, with the suspension system in a neutral state. Avoid curbs or slopes in front of the device. Install the attenuator on a smooth surface (usually concrete) so it can com­press uniformly. Conspicuous, well-delineated crash cushions are less likely to be hit than those that blend into the background. If the system is not reflective, install stan­dard object markers to improve visibility at night and during inclement weather.

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Lognormal distribution

Posted by on 20/ 11/ 15

Consider a random variable X having a lognormal distribution with a mean H-x and standard deviation ox, that is, X ~ LN(^x, ox). For a lognormal random variable X, its logarithmic transform Y = ln(X) leads to a normal distribution for Y. The PDF of X is given in Eq. (2.65). In the log-transformed space, the mean and standard deviation of ln(X) can be computed, in terms of цx and ox, by Eqs. (2.67a) and (2.67b). Since Y = ln(X) is normally distributed, the generation of lognormal random variates from X ~ LN(^x, ox) can be obtained by the following steps:

1. Calculate the mean ^ln x and standard deviation oin x of log-transformed vari­able ln(X) by Eqs. (2.67a) and (2.67b), respectively.

2. Generate the standard normal variate г from N(0,1).

3. Compute y = ,u. lnx + olnxZ.

4...

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GUTTERS AND GUTTER GUARDS

Posted by on 20/ 11/ 15

Gutters are sometimes required by code. When com­bined with downspouts and their associated fittings, gutters help keep water away from the foundation, pre­venting serious erosion and reducing water accumula­tion under the house. Gutters, downspouts, attachment hardware, and other components are available at most building-supply outlets. Also, consider buying and

installing gutter guards, especially if there are large trees nearby. Different types of gutter guards are avail­able, but they all perform the same function of keeping leaves, seedpods, and other debris out of the gutter while allowing water in. This eliminates the annual (or more frequent) chore of having to climb up on a ladder or onto the roof to clean out the gutters.

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Diaphragm Framing Tasks of Particular Concern

Posted by on 20/ 11/ 15

• Nail spacing—The nailing pattern for nailing the sheathing to the intermediate framing members is usually the standard 12" O. C. It is the edge nailing that changes to increase the strength.

• Penetration—The nail must not penetrate the sheathing’s outside veneer.

Nail Penetration

3/8" minimum from nail to edge of sheathing

/8" minimum gap

• Nail size—The nail sizes will vary based on the engineer’s design, or code requirements. Check the specified thickness and length.

• Blocking—It is common to have blocking in the joist space that runs parallel to the exterior walls. It will be detailed on the plans if it is required. Blocking can also be used on the edges of the sheathing.

Connections

“Connectors" can refer to beams or other construction elements, but in most c...

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