Blog Archives

Basic Principles of Heat Transfer

Posted by on 14/ 11/ 15

The basic principles to model the complete time-dependent heat transfer in soils are described in this section. More details of these and the associated effects can be

found in some of the better or more specialist geotechnical textbooks, for example Mitchell and Soga (2005) or Fredlund and Rahardjo (1993).

The water content in various road structures and the underlying soil are subject to climatic (temperature) effects. An example of the thermal variation in a road structure is given in Fig. 4.1. It can be clearly seen that the thermal state is definitely changing, which means that it is characterised by the heat transfer properties of the material. Temperatures may be positive or negative (inducing freezing)...

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Installing Hardware

Posted by on 14/ 11/ 15

Specifics vary, but most locksets come with paper templates that locate the center of the holes drilled in the face of the door (face bores) for handle spindles or cylinders and holes drilled into the edge of the door (edge bores) for latch assemblies. A second paper template locates holes drilled in the latch jamb of the door frame. Although the directions given in this section are typical, follow the directions supplied by your lock maker. Note: Measure the door thickness before buying locksets or key cylinders; some mechanisms are adjustable; others fit only specific door thicknesses.

Mortise Lockset

Mortise locksets combine security and convenience, because you can use a single key to operate both a latch bolt and a dead bolt.

Подпись:Подпись:MORTISE LOCKSETS

Mortise locksets house latch bolts and dea...

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Part iv: impact of the Grains’ Density

Posted by on 14/ 11/ 15

The appearance of significant differences in density among individual fractions of the aggregate mix compels us to discuss volume relations in the aggregate mix and necessary adjustments to the binder content

Substantial differences in the densities of aggregates combined in an SMA can cause numerous problems. This situation happens rather seldom; however, it is pos­sible to find very light material combined with very heavy aggregate (e. g., densities of approximately 2.400 and 3.100 Mg/m3, respectively). When designing a particular mix, results of the sieve analysis of constituent aggregates, as well as the overall gradation curve of a mix, indicate the gradation sieve distribution in mass units...

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Beta distributions

Posted by on 14/ 11/ 15

The beta distribution is used for describing random variables having both lower and upper bounds. Random variables in hydrosystems that are bounded on both limits include reservoir storage and groundwater table for unconfined aquifers.

The nonstandard beta PDF is

Подпись: 1

Подпись: f NB(x | a, b, a, в) = ■WI. —j—r(x – a)a 1(b – x)e 1 for a < x < b B(a, в)(b – a)a+e-1 “ “

(2.96)

Подпись: Г(д)Г(в) na + в) Подпись: B(a, в) = Подпись: (2.97)

in which a and b are the lower and upper bounds of the beta random variable, respectively; a > 0, в > 0; and B(a, в) is a beta function defined as

Using the new variable Y = (X — a)/(b — a), the nonstandard beta PDF can be reduced to the standard beta PDF as

f B(y | а, в) = 1 Уа—1(1 — y)e—1 for 0 < y < 1 (2.98)

B(а, в)

The beta distribution is also a very versatile distribution that can have many shapes, as shown ...

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Rigid Pavement Joint Sealing

Posted by on 14/ 11/ 15

Joint sealing prohibits the infiltration of water into the pavement base and prevents incompressibles from lodging within the joint cavity. The advantages of keeping water out from under a pavement are documented extensively in the AASHTO Pavement

Rigid Pavement Joint Sealing

FIGURE 3.4 Layout of joints in rigid pavement at skewed intersection. Conversions: 1 in = 25.4 mm, 1 ft = 0.305 m.

Rigid Pavement Joint Sealing

FIGURE 3.5 Layout of joints in rigid pavement at right-angle intersection. Conversions: 1 in = 25.4 mm, 1 ft = 0.305 m.

 
Подпись: 229

1/в" recess Top of pavement

Rigid Pavement Joint Sealing

 

Design Guide and in various articles in this chapter. With an unsealed joint, contraction under cooler temperatures allows joint cavities to open up and become filled with sand, stone, and other incompressible material...

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Heat Transfer in Soils

Posted by on 14/ 11/ 15

Ake Hermansson[6], Robert Charlier, Frederic Collin, SigurSur Erlingsson, Lyesse Laloui and Mate Srsen

Abstract Temperature highly affects pavement performance. High and low tem­peratures not only affects the viscosity of asphalt concrete but also has an impact on the moisture flow within pavements. At temperatures below 0°C the freezing of pavements dramatically changes the permeability and frost action might occur forcing water to flow upwards to the freezing front resulting in frost heave and other pavement distress.

Keywords Heat transfer ■ conduction ■ temperature ■ frost

4.1 Introduction

The thermal state may have a major influence on the moisture condition of a pave­ment or foundation...

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SOLID RAILING AT PORCH OR DECK

Posted by on 14/ 11/ 15

Open railings are connected to the floor of a porch or deck only intermittently, where the vertical supports occur. It is through these supports that open railings gain their rigidity. When the end of the railing is sup­ported at a wall or a column, no special connections are required. When the vertical support does not coin­cide with a rigid part of the structure, however, a rigid connection must be made with the floor system of the porch or deck. One logical place to locate this con­nection is at the inside edge of the rim joist (see the drawing below).

SOLID RAILING AT PORCH OR DECK

Another logical place to secure the railing to the porch floor is at the outside of the rim joist (see the drawing below)...

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More to the south: hydraulic works at the second cataract

Posted by on 14/ 11/ 15

The pharaohs of the middle Empire tried to develop fluvial commerce with Nubia while at the same time protecting themselves from Nubia. Sesostris III extends the border of Egypt up to Semna, beyond the second cataract. A stela contains the following text: “Southern border established in year 8 of his majesty the king Khakaoure (Sesostris III), so as to prevent any Nubian from crossing it, by land or boat, neither any Nubian herds; except Nubians who would come to do commerce in Iken (Mirgissa), but not to the point that any Nubian boat travels to the north beyond Heh (at the northern outlet of the pass of Semna), 17

ever.

The pass at Semna is fortified to enforce this proclamation, and to tightly control traffic on the Nile...

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FINE-TUNING FRENCH DOORS

Posted by on 14/ 11/ 15

Now it’s time for fine-tuning the installation or, as the pros call it, working the frame. Here are a few things you might see and what to do about each:

► Doors hitting in the center. Ease off the shims behind the jambs. If the problem is a bowed jamb, use additional nails to pull it back toward the RO or, better yet, use 2h-in. screws.

► Doors too far apart in the center. Shim out from the RO more. If that doesn’t work or if you must shim so much that the center of the jamb bows, the head jamb was probably milled too long and should be cut down. The gap between the double doors should be 54e in. or whatever the manufacturer suggests.

► Wider gap between doors near the top. Shim out behind a top hinge on one side.

► Uneven door heights, binding in a corner...

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Rigid Pavement Jointing Details for Intersections

Posted by on 14/ 11/ 15

The following basic principles must be observed in developing a correct jointing detail:

1. Never taper concrete down to less than 2 ft (610 mm) in width.

2. Depending upon the amount of transverse reinforcing steel, be careful of the number of lanes that are tied together. In JPCP, tying more than three 12-ft (3.7-m) lanes together may result in uncontrolled longitudinal cracking.

3. Always design the secondary (intersecting) route as independent in movement from the primary route. Thus, as the primary route expands and contracts, no unnecessary forces will be created in the secondary route.

4. Provide for expansion wherever payment is interrupted in its longitudinal direction.

5. Terminate joints at 90° to any intersecting joints, obstructions, or edges of pavement.

6...

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