Blog Archives

LAYDOWN CONDITIONS

Posted by on 18/ 11/ 15

Due to the resistance to compaction provided by the coarse aggregate skeleton, SMA mixtures can cause problems during laydown. Thus in almost all countries that have adopted SMA, some additional requirements on conditions at the work site must be observed, including the appropriate temperature, wind velocity, and the absence of rain.

10.2.1 Minimum Temperature of Air and Underlying Layer

To ensure that weather conditions are acceptable during laydown, the air tempera­ture may be checked often. In many countries, however, air temperature is not as important as the temperature of the course on which the hot mixture is going to be placed...

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Time-dependent reliability models for hydrosystems

Posted by on 18/ 11/ 15

Considering only inherent hydrologic uncertainty. Traditionally, the risk associ­ated with the natural hydrologic randomness of flow or rainfall is explicitly considered in terms of a return period. By setting the resistance equal to the load with a return period of T years (that is, r* = lT), the annual reliability, without considering the uncertainty associated with lT, is 1 – 1/T, that is,

P (L < r *|r * = tT) = 1 – 1/T. Correspondingly, the reliability that the random loads would not exceed r * = lT in a period of t years can be calculated as (Yen, 1970)

Ps(t, T) = (4.108)

For large T, Eq. (4.108) reduces to

Ps(t, T) = exp( t/T) (4.109)

If T > t, Eq. (4.108) can further be approximated simply as ps(t, T) = 1 -1/T.

Considering both inherent hydrologic uncertainty and hydraulic uncertai...

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Shingling across a valley

Posted by on 18/ 11/ 15

When a porch roof intersects the main roof at a right angle, a valley is formed. Shingles can be laid across a valley in different ways.

A woven valley is formed by weaving shingles across the valley, alternately overlapping from the main roof onto the porch roof, then vice versa. When properly done, a woven valley is watertight. Let each course of shingles overlap the valley by at least 12 in. and keep nails 8 in. or more from the centerline of the valley.

Подпись:Подпись: Save your knees when shingling. A foam pad makes a great cushion when you're nailing roof shingles. If a pad isn't convenient for you to use, try wearing cushioned knee pads. Подпись: iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiAn alternative to a woven valley is a closed, or cut, valley. To create a cut valley, let all shingle courses from the main roof lap across the porch valley by at least 12 in. Don’t alter­nate back and forth from the main roof to the

It’s hard work to hand up sheathing panels.

We yell back and forth from the roof to the ground...

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RETAIL STORES

Posted by on 18/ 11/ 15

The minimum fixture requirements for retail stores differ from the examples that we have just been working with. However, the concept and approach of computing the needs is same. Refer to Figure 9.3 for listings that pertain to retail stores. You can see that the table is very similar, in layout, to the one we have just been using. Pay particular attention to the number 6 at the heading of retail stores. Refer back to Figure 9.2 for an explanation of the note. You will find that one bathroom facility can be used by both males and females in certain types of occupancies. For example, an office with 1200 square feet, or less, can be served by a single restroom for both sexes...

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Remedying a Mold Problem

Posted by on 18/ 11/ 15

Remedying a Mold Problem

if you think you have a mold problem or if you are sick in your home and suspect mold is to blame, I recommend contacting a reputable professional to do an investigation. The self-test kits found at local hardware stores are not accurate. They may tell you there is a problem when there is not and they are not good at detecting Stachybotrys, one of many problematic types of mold. Stachybotrys has frequently been referred to as "black mold," but there are many types of mold that are black. You can’t judge a mold by its color; there are some types of edible mold that are black and other molds that aren’t black but are probably every bit as bad as if not worse than Stachybotrys. So get­ting a competent diagnosis is important.

Several states have licensing requirements for mold inspectors...

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Time-dependent reliability models

Posted by on 18/ 11/ 15

Reliability computations for time-dependent models can be made for determin­istic and random cycle times. The development of a model for deterministic cycles is given first, which naturally leads to the model for random cycle times.

Number of occurrences is deterministic. Consider a hydrosystem with a fixed resistance (or capacity) R = r subject to n repeated loads L1, L2,…, Ln. When the number of loads n and system capacity r are fixed, the reliability of the system after n loadings ps(n, r) can be expressed as

Ps(n, r ) = P [(L1 < r ) n (L2 < r ) П—П (Ln < r )] = P (Lmax < Г ) (4.100)

where Lmax = max{L1, L2,…, Ln}, which also is a random variable. If all ran­dom loadings L are independent with their own distributions, Eq. (4.100) can be written as

Ps(n, r) = [FLi(r)] (4.101)

i=1

wh...

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Interior walls

Posted by on 18/ 11/ 15

Once the exterior wall lines are accu­rately in place, you can measure off them to get the location of interior walls. Just keep an eye on the plans to get the dimensions right.

Laying out the long interior walls next makes it easier to locate and mark all the short, 2×4 walls that make up closets and bathrooms. Watch the floor plan. It may show that an interior bedroom wall is 12 ft. 7 in. from the outside of the building to the center of the 2×4 wall. Because half of ЗУ2 in. is 13A in., add 13/д in. to 12 ft. 7 in. to get the overall dimension of this wall, which is 12 ft.

83/д in. from outside to outside.

Measure in this distance from the out­side of the exterior wall of the slab or floor deck, mark it, and place an X to the inside of the mark, as shown in the drawing on the facing...

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Modeling intensity and occurrence of loads

Posted by on 18/ 11/ 15

A hydraulic structure placed in a natural environment over an expected ser­vice period is subject to repeated application of loads of varying intensities. The magnitude of load intensity and the number of occurrences of load are, in gen­eral, random by nature. Therefore, probabilistic models that properly describe the stochastic mechanisms of load intensity and load occurrence are essential for accurate evaluation of the time-dependent reliability of hydrosystems.

Probability models for load intensity. In the great majority of situations in hy­drosystems reliability analysis, the magnitudes of load to be imposed on the system are continuous random variables. Therefore, univariate probability dis­tributions described in Sec. 2...

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Other Techniques for Discharging Mixture

Posted by on 18/ 11/ 15

Special self-propelled hoppers (e. g., MTVs) have been used to avoid segregation dur­ing the discharge of a mixture from the dump truck to the paver hopper and to minimize the risk of placing cool mixture (by remixing). These mobile machines operate between the dump truck and the paver to eliminate any contact between the two. MTVs are equipped with conveyors to transport the mixture to the paver hop­per. These devices eliminate jarring of the paver caused by contact with the delivery trucks or by the mass of mix dropping into the hopper. They hold a larger mass of material than a paver hopper, which helps to keep the temperature high, and allows the paver to keep moving forward. Another advantage of MTVs is the possibility of remixing the mixture constituents...

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Hydraulics in the Roman empire: Driving Force of development and symbol of civilization

Posted by on 18/ 11/ 15

The Etruscan hydraulic heritage and the beginnings of Rome

Civilization does not truly begin to develop in the western Mediterranean until the begin­ning of the 8th century BC. This begins according to the legend when the Phoenicians, led by Elissa, princess of Tyr, found Carthage on the Tunisian coast. Then the Greeks establish colonies in Sicily and in the south of the Italian peninsula in the middle of the 8th century BC. These colonies become a cultural ensemble called Greater Greece. But the capital event for Italy during this same period is the arrival of yet another people who settle to the north of the Tiber. According to Herodotus, these new arrivals came from Anatolia...

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