Blog Archives

Watershed Characteristics

Posted by on 17/ 11/ 15

Characteristics of the watershed area directly affect the hydrologic analysis. Basic fea­tures of the watershed basin include size, shape, slope, land use, soil type, storage, and orientation.

The size of the watershed basin is the most important characteristic affecting the determination of the total runoff. It is generally measured in acres, square miles, or square kilometers and is defined by the limits of the topographic divide. A topographic divide is a line that separates water flow between basins, thus causing the rainfall that falls on one or the other side to flow into a particular watershed. The location of this divide, and thus the perimeter of the basin, may be determined from aerial photographs, topographic maps available from the U. S...

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Exterior Sheathing

Posted by on 17/ 11/ 15

Exterior sheathing in wood frame construc­tion is attached to the outside of the frame and makes up the surface to which the exte­rior finish is applied. Before manufactured sheet goods such as plywood were available, ix or 2x material was nailed to the studs for this purpose. In standard wood frame construc­tion today, exterior-grade plywood or OSB (oriented strand board, also known as wafer – board) is typically used as exterior sheath­ing for the entire building or at corners where shear strength is required. These materials contain varying degrees of formaldehyde and isocyanates and do not have the longevity of solid wood products.

Many problems with the use of OSB in roof and wall sheathing have recently been iden­tified...

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Remembering Common Sense

Posted by on 17/ 11/ 15

Most of our new houses are really not designed at all, but assembled without much thought for their ultimate composition. Architects seldom have anything to do with the process. Instead, a team of marketing engineers comes up with a product that will bring in more money at less cost to the developer. The team’s job is to devise a cheap structure that people will actually pay good money for. Low-grade, vinyl siding, ornamental gables and asphalt shingles have become their preferred medium. Adding extra square footage is about the cheapest, easiest way there is to increase a property’s market value, so it is applied liberally without any apparent attempt to make the additional space particularly useful. The final product is almost always a bulky conglomeration

of parts without cohesion ...

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Roof and Floor Framing

Posted by on 17/ 11/ 15

Solid beams, round logs, or 2X joisting are commonly used for shorter roof spans. Man­ufactured trusses, typically made of compos­ite wood products and assembled into profiles engineered for strength, are commonly used for longer spans. They have several advantages over solid lumber. They are less expensive, use wood resources more efficiently, have greater span capabilities, provide a deep pocket for roof insulation, and can be fabricated with a built-in slope for flat roof application.

Truss joists, commonly called TJIs, are manufactured beams containing either ply­wood or dimensional lumber for top and

Подпись: Ceiling framing components.
Roof and Floor Framing

bottom chords, and either plywood or press – board for the webs...

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HYDROLOGY

Posted by on 17/ 11/ 15

The science of hydrology is concerned with the estimation of the intensity of rainfall, the
distribution of the flow of the rainwater over the land, and the determination of the flow quan-
tity (peak and total) that eventually reaches some specified point, the “point of solution.”

Of primary concern to the highway engineer is the frequency of occurrence of the peak discharge. Although many methods for determining runoff have been proposed over the years, making an accurate prediction is difficult, because of the many and varying para­meters that contribute to the complexity of the problem. These parameters include the affected drainage area, the rainfall intensity, the time of concentration of the rainfall, and the percent of the rainfall that will actually reach the point of solution...

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Harmony of simplicity in a bathroom

Posted by on 17/ 11/ 15
Many people like a Japanese miniatyurizm where there is nothing excessive, and the preference is given to natural materials and usual forms. Perhaps, the similar design is more necessary at registration of bathrooms. In - 1-x, there we deal with a limited read more

Working with Brick

Posted by on 17/ 11/ 15

Common brick-related repairs include repoint­ing mortar joints, repairing chimney tops, rebuilding chimneys and fireboxes, and cleaning bricks. You may also have to repair or add flash­ing where the chimney meets the roof, as shown in Chapter 5. Less common repairs include filling openings after the removal of doors or windows. If you want to create an opening to a brick wall, leave that to a structural engineer and a licensed and insured mason.

To conserve resources and get the best­looking results, respect existing masonry. Match existing bricks and mortar as closely as possible, including the thickness of mortar joints.

When repointing brick, choose a mortar of appropriate strength.

TYPES AND TERMS

Of the many types of brick available, renovation calls mainly for building brick, also...

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Kevin E. White, P. E

Posted by on 17/ 11/ 15

Principal Hydraulic Engineer
E. L. Robinson Engineering
Columbus, Ohio

A properly designed highway requires a well-designed drainage system. This requires a determination of the quantity of runoff reaching the drainage structures and an accurate analysis of water flow through the structures in order to properly size them. Also, a working knowledge of structural characteristics of buried pipe systems and effects of environmental factors is necessary to provide for long-term performance. Timely inspection and maintenance of drainage facilities will ensure satisfactory service life. If all of these issues are properly addressed, an efficient drainage system can be devel­oped...

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SEISMIC DESIGN

Posted by on 17/ 11/ 15

In recognition of the serious potential destructive effects of earthquakes, AASHTO specifications contain comprehensive provisions for seismic design. Although earlier speci­fications contained some provisions, the more comprehensive provisions were not adopted until the 1980s. They were based on a detailed study by consultants who were specialists in that field, with review and participation by bridge engineers and design firms. The standards developed apply to conventional steel and concrete girder and box girder construction with spans up to 500 ft, but do not cover suspension, cable – stayed, arch-type, and movable bridges.

Bridges and components designed to the AASHTO seismic provisions may suffer damage under severe seismic events, but should have a low probability of collapse due t...

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PROVISION FOR INSPECTION OF NEW BRIDGES

Posted by on 17/ 11/ 15

In the design of a new bridge, provision must be made for maintenance inspection. For example, plate girders can be provided with safety handrails, safety railings can be specified on top of wide piers for inspectors to check bearings, and safety ladders can be installed to provide access to elements of the bridge otherwise difficult to reach. For deck-type bridges of moderate span and width, it will be possible to access the superstructure from special bridge inspection vehicles operating on the deck. For longer spans where the depth of girder exceeds the vertical capacity of a boom, and for wider bridges where the horizontal reach of the boom is not adequate, it may be necessary to provide catwalks or permanent movable inspection platforms...

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