Structural Steel
Steel for bridges is available in several different strength levels, each of which may be specified under ASTM A709, Standard Specification for Structural Steel for Bridges.
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TABLE 4.1 Steels for Bridges
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Blog Archives
Rain Gutters
Gutters direct water away from the house, preventing water from collecting next to the foundation and thereby possibly undermining it. The two most common gutter profiles are half-round and K-style, in which the gutter has a squared-off back and an ogee front. For appearance’s sake, try to match the profile of new gutters to old.
To clear water adequately, gutters must be sized properly and cleared of leaves and debris twice a year—in spring and in fall. Your lumberyard probably has elaborate gutter-sizing charts based on regional rainfall, roof square footage, and pitch. But you might remedy chronically overflowing downspouts simply by upsizing the gutters from a standard 5-in. width to a 6-in. model and installing larger downspouts. To keep
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Begin any gutter installation b...
read moreBASIC BRIDGE MATERIALS
The basic materials most often used to construct bridges are concrete and steel. Timber is occasionally used for deck construction and sometimes for short-span bridges.
High strength is desirable for bridge concrete to reduce member size and weight, but durability is equally or more important. Component materials must be compatible with each other, and the concrete must have low permeability.
A long-term destroyer of concrete from within is alkali-silica reaction. While material specifications for concrete have been developed to preclude use of cement and aggregates that will produce alkali-silica reaction, the best prevention of this problem is the use of cements and aggregates from sources that have a known history of absence of this problem.
Given that required strength...
read moreHydraulics in the Mycenaean civilization in the second millennium BC
At the beginning of agriculture in Greece, Vth millennium BC, the abundant precipitation of spring and autumn obviated the need for irrigation. But irrigation eventually does develop in the Greek world. The earliest written reference to it comes from the Iliad:
“As one who would water his garden leads a stream from some fountain over his plants, and all his ground-spade in hand he clears away the dams (blockages) to free the channels, and the little stones run rolling round and round with the water as it goes merrily down the bank faster than the man can follow (.. .)”n
The Mycenaen civilization that develops especially from 1600 BC is the cultural heir of the Cretan civilization...
read moreMethods of Earth Construction
Earth is widely available at little or no cost. It is nonflammable, is infinitely recyclable, is
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condensing. Even if water does condense, there is always an exit pathway for it. Natural building materials such as earth, cob, and masonry are especially well suited for this task. To create a fully functional wall based on the flow-through design, any healthy home project must take into account all the climate-specific details of its location.
a. Max von Pettenkofer. Uber den Luftwechsel in Wohngebauden. Literarisch-Artistische Anstalt der J. G. Cotta’schen Buchhandlung, 1858.
b. Erwin Raisch/’Die Luftdurchlassigkeitvon Bau – stoffen und Baukonstruktionsteilen." Gesund- heitsingenieur. Issue 30 (1928).
c. Winfried Schneider. "40 Jahre Baubiologie – Klischees, lnnovationen, Trends...
read moreWET VENTING
Wet venting is popular, but a little different when it comes to sizing the vents. Tables can still be used for this type of sizing. Look at Figure 5.34 for an example of a table that might be used to size a wet stack vent. Another type of table that you might encounter is shown in Figure 5.35. This table is intended for use in sizing a vent stack for wet venting.
Keep in mind that not all plumbing codes are the same, and they may present their information differently. It is also important to remember that requirements may be different.
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BRIDGE GEOMETRICS
Bridge Width. Roadway width on bridges is the inside measurement to the bottom of the sidewalk curb or the bottom of the safety barrier. For bridges on roads where sidewalks are not provided, the bridge width is made equal to the approach roadway width including shoulders, so that the bottom of the barrier curb or the near face of the railing is aligned with the face of the barrier rail at the outside edge of the shoulder.
In the past, policy did not always permit full shoulders to be accommodated on bridges. Often the roadway was made narrower, particularly on longer bridges. This was done strictly to reduce bridge cost. From the traffic operations standpoint, however, it was an unwise practice...
read moreWall
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he walls of a building serve several important functions: They define the spaces within the building to provide privacy and zoning, and they enclose the building itself, keeping the weather out and the heat or cold in. Walls provide the vertical structure that supports the upper floors and roof of the building, and the lateral structure that stiffens the building. Walls also encase the mechanical systems (electrical wiring, plumbing, and heating). To incorporate all of this within a 4-in. or 6-in.-deep wood-framed panel is quite an achievement, so numerous decisions need to be made in the course of designing a wall system for a wood-frame building. There are two preliminary decisions to make that establish the framework for the remaining decisions.
wall thickness
Should the wal...
read moreThe Breathing Wall Concept: Misconceptions
The breathing wall concept goes back to Max von Pettenkofer (1818-1901), one of the most accomplished hygienists of his time and the pioneering founder of the occupational and environmental hygiene sciences as we know them today. He was instrumental in stopping the cholera epidemics in Munich, one of the largest cities in Germany, during the second half of the 19th century. By initiating the construction of a central water supply and sewage treatment system, he greatly improved public health and achieved celebrity status.
In his dedicated search for better living conditions, von Pettenkofer introduced carbon dioxide measurement as an important indicator of overall indoor air quality...
read moreSmall Leaks Add Up, So Seal Them All
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sually, the greatest number of leaks comes from small perforations in the ceiling: metal electrical boxes, drywall seams, and any place a wire or pipe comes through from below. Use expanding urethane foam to seal holes around PVC vent pipe (1), in electrical boxes (2), and especially at ceiling-corner drywall seams (3). If any of the sealing comes under local regulations for fire-stopping or draft-stopping, then use fire – or smoke-rated foam or caulking.
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