Blog Archives

Dampproofing for Foundation Walls

Posted by on 17/ 11/ 15

The use of asphaltic and bituminous tar mix­tures for dampproofing is standard practice. These petrochemical-based materials are known carcinogens. There are several other readily available products made for this pur­pose that are more healthful choices. The fol­
lowing products may be specified for damp­proofing foundation walls or other walls adjacent to soil:

Cementitious Dampproofing

• Thoroseal Foundation Coating: A ce­mentitious dampproofing for concrete and concrete masonry unit (CMU) surfaces.

• Xypex: A nontoxic (according to man­ufacturer), zero-VOC chemical treat­ment for dampproofing and protection of poured concrete, it creates a nonsoluable crystalline structure that permanently

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Method for Testing the Increase in Mortar Viscosity

Posted by on 17/ 11/ 15

Some references to a method consisting of the testing of mortar viscosity and com­paring it with the pure binder viscosity may be found in the literature. By and large, such a comparison would be a stiffening factor. However, as it has been pointed out in Anderson’s work (Anderson, 1987), not only do the filler properties affect that factor but the properties of the binder used for testing do as well. Certainly the reli­ability of that method is controversial.

8.3.2 Other Factors and Filler Tests

8.3.4.1 German Filler Test

An interesting and simple method of testing fillers is that discussed in the study by Kandhal et al. (1998). Called the German Filler Test,[55] it consists of determining the amount of filler required to absorb 15 g of hydraulic oil and is carried out as follows:

1...

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Inlet Location and Type

Posted by on 17/ 11/ 15

One of the major objectives in the design of the roadway drainage system is to limit the encroachment of the flow to that developed in the roadway drainage guidelines. However, this spread cannot be determined until the inlet is located. After the inlet is located, the drainage area contributing to the flow into that inlet is determined. Discharge based on the rational method is then calculated, and finally the spread is deter­mined based on that discharge and the gutter characteristics. If the spread is found to be too great (leading to possible unsafe conditions) or too small (possibly indicating an inefficient design), the inlet should be relocated and the process repeated. As can be seen, this design is an iterative process...

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Treatment of nonnormal stochastic variables

Posted by on 17/ 11/ 15

When nonnormal random variables are involved, it is advisable to transform them into equivalent normal variables. Rackwitz (1976) and Rackwitz and Fiessler (1978) proposed an approach that transforms a nonnormal distribu­tion into an equivalent normal distribution so that the probability content is preserved. That is, the value of the CDF of the transformed equivalent nor­mal distribution is the same as that of the original nonnormal distribution at the design point x*. Later, Ditlvesen (1981) provided the theoretical proof of the convergence property of the normal transformation in the reliability algo­rithms searching for the design point. Table 4.3 presents the normal equivalent for some nonnormal distributions commonly used in reliability analysis.

By the Rackwitz (1976) approach, t...

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Curbs, Gutters, and Inlets

Posted by on 17/ 11/ 15

The roadway surface water can be removed by a series of drains that carry the water into a collection and disposal system. The curb, gutter, and inlet design must keep flooding within the parameters established in roadway drainage guidelines. The hydraulic efficiency of inlets is related to the roadway grade, the cross-grade, the inlet geometry, and the design of the curb and gutters.

Curbs are divided into two classes: barrier and mountable. Barrier curbs are steep­faced and generally 6 to 8 in (150 to 200 mm) high. Mountable curbs are generally 6 in (150 mm) high or less with relatively flat sloping faces to allow vehicles to cross them when required. Neither barrier curbs nor mountable curbs should be used on high­speed roadways. (See Chap. 6, Safety Systems.)

Gutters begin at the bot...

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Openings in Brick Walls

Posted by on 17/ 11/ 15

If you want to add a door or window to a brick wall, hire a structural engineer to see if that’s feasible. If so, hire an experienced mason to create the opening; this is not a job for a novice. If the house was built in the 1960s or later, the wall will likely be of brick veneer, which can be relatively fragile because the metal ties attaching a brick veneer to wood – or metal-stud walls tend to rust out, especially in humid or coastal areas. In extreme cases, steel studs will rust, and wood studs will rot. Thus, when opening veneer walls, masons often get more of a challenge than they bargained for.

Brick homes built before the 1960s are usually two wythes thick (with a cavity in between), are very heavy, and have very likely settled...

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Algorithms of AFOSM for independent normal parameters

Posted by on 17/ 11/ 15

Подпись: W '(z (r)) a |Vz' W'(Z (r ))| (r>

Подпись: Z (r +1) ( a(r ) z (r )) a(r )
Подпись: for r = 1,2,... (4.51)

Hasofer-Lind algorithm. In the case that X are independent normal stochastic basic variables, standardization of X according to Eq. (4.30) reduces them to independent standard normal random variables Z’ with mean 0 and covariance matrix I, with I being a K x K identity matrix. Referring to Fig. 4.8, based on the geometric characteristics at the design point on the failure surface, Hasofer and Lind (1974) proposed the following recursive equation for determining the design point z (.

Подпись:Подпись: for r = 1,2, 3,... (4.52)

Подпись: Vx ) S(r) — W (x (r)) s(r)D xs (r)
Подпись: x (r + 1) — + D xs(r)

in which subscripts (r) and (r + 1) represent the iteration numbers, and —a denotes the unit gradient vector on the failure surface pointing to the failure region. Referring to Fig. 4.9, the first terms of Eq. (4...

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DESIGN OF ROADWAY DRAINAGE

Posted by on 17/ 11/ 15

Roadway drainage includes the entire system from pavement drainage through storm drains. Drainage features that make up the system include curbs, gutters, drop inlets, median drains, overside drains, roadside ditches, and storm drains. The basic design procedure for roadway drainage includes hydrology, surface water removal, and dis­posal. A properly designed system must adequately accommodate the design runoff by removing it from the roadway surface and conveying it to the outfall, avoiding damage to adjacent property and roadway hazards from overflowing and ponding.

3.4.1 General Considerations

Pavement may be drained in one of two ways. The runoff may be allowed to sheet – flow across the roadway surface and into roadside ditches...

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Symbolic Meaning

Posted by on 17/ 11/ 15

Vernacular architects have at their disposal not only what they have assimil­ated from books, travel and the work of their ancestors but a lot of hard-wired knowledge as well. Human beings have an innate understanding of certain forms. We are born liking some shapes more than others, and our favorites turn up frequently in the art of young children and in every culture. Among these is the icon representing our collective idea of home. Everyone will un­doubtedly recognize the depiction of a structure with a pitched roof, a chim­ney accompanied by a curlicue of smoke and a door flanked by mullioned windows. Children draw this as repeatedly and as spontaneously as they do faces and animals...

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STEP 4 SECURE THE TRUSSES TO THE INTERIOR WALLS

Posted by on 17/ 11/ 15

On small houses, trusses are generally engi­neered to obtain their support from exterior walls without needing further support from interior walls. Still, it’s not uncommon for trusses to cross over and bear on interior walls. In most regions, these trusses can usually be nailed directly to the interior wall with two 16d toenails on one side and one on the opposite side. This is not the case, however, if you live in a part of the country where the weather may be freezing one day and boiling the next. In areas with extreme temperature fluctuations, trusses must be able to expand and contract freely. Otherwise, drywall ceilings nailed to these trusses tend to crack. Check with your building department for the code requirements in your town or city...

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