Blog Archives

DETERMINATION OF SPAN LENGTHS

Posted by on 17/ 11/ 15

Where the spans are not controlled by features crossed—such as roads, railroads, streams, or existing buildings—and there is freedom to locate piers, the lengths of spans will be controlled by aesthetic, economic, and structural requirements. Generally, from an aesthetic standpoint, spans should have a length at least 3 or 4 times the pier height.

The profile of the site crossed will influence the span proportions. On the uphill end of a crossed hillside, the end spans will be shorter than at the bottom of the valley. The type of bridge will also affect the selection of span ratios, from both aesthetic and structural standpoints...

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FRAMING A DOOR OR WINDOW OPENING

Posted by on 17/ 11/ 15

After cutting back interior surfaces to expose the framing in the exterior wall, outline the RO by snapping chalklines across the edges of studs. If you can incorporate existing studs into the new opening—an old stud might become the king stud of the new opening, as shown in the photo on p. 165—you can save time and materials.

To remove old studs within the new opening, use a sledge to rap the bearing wall’s top plate upward, thus creating a small gap above the studs (and old header, if any). That should create enough space to slip in a metal-cutting reciprocating-saw blade and cut through nails holding studs to the top plate. Though sheathing or siding may be nailed to the studs, they should still pull out easily.

Start framing the new opening by toenailing the king stud on both sides...

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Brief history of the Hellenistic kingdoms and their successors1

Posted by on 17/ 11/ 15

Setting out from Macedonia, with contingents of Macedonian and Greek soldiers, Alexander achieved a first victory over the Achaemenid King Darius II, who ruled the Persian Empire, at the battle of Issus. Egypt falls without resistance into the clutches of Alexander, who makes a long sojourn there from 332-331 BC. During this sojourn, he founds Alexandria on the seafront, an ideal site for the development of commerce, lying [163] between the sea and a lagoon. But the site is poorly supplied with fresh water, being some distance from the Nile. Considerable engineering efforts are undertaken to support the burgeoning activity of the city (Figure 5.2)...

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Exterior Foam Is a Good Option

Posted by on 17/ 11/ 15

Adding exterior foam to walls works well for new construction. As long as you meet local wind and earthquake codes, it’s usually pos­sible to build a foam-sheathed wall without structural oriented strand board (OSB) or plywood sheathing. Foam-sheathed walls are braced using one of four methods:

• Diagonal 1×4 let-in braces.

• Diagonal T-profile steel strapping, such as Simpson TWB.

• Inset shear panels.

• A few strategically placed pieces of OSB (they are usually installed at corners).

Of course, you should check with an engineer and your local building official before finalizing your wall-bracing plan.

Exterior foam sheathing is often installed on existing homes as an energy-saving

retrofit when new roofing or siding is need­ed...

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COMMON TRUSSES FOR GABLED ROOFS

Posted by on 17/ 11/ 15

COMMON TRUSSES FOR GABLED ROOFSCOMMON TRUSSES FOR GABLED ROOFSCOMMON TRUSSES FOR GABLED ROOFS

Подпись: Delivery right on the walls. It saves time and energy to have the truss company deliver the trusses and lay them right on the top plate of the framed walls. [Photo © Elmer Griggs]

be open or closed. For details on different ways to finish off an eave, see the sidebar on p. 117. NUMBER OF TRUSSES. Roof trusses are typically spaced 24 in. o. c. Therefore, if your building is 40 ft. long, you’ll need to order 21 trusses. Two of the trusses will be for the gable ends. These trusses have studs rather than webbing to receive the exterior wall covering. SPECIAL REQUIREMENTS. If your house has a more complex roof, special trusses may be required where one roof section joins another. Often houses are built in a “T” or “L” shape or have a side porch that connects to the main roof. You can cut the rafters needed to tie the porch roof to the main roof...

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DRAINDOWN TESTING

Posted by on 16/ 11/ 15

The draindown effect is the process of the separation of liquid binder or mastic from an SMA mixture that occurs at a high temperature when the binder is still molten.

Both the binder and the mastic can separate. It is common knowledge that SMA mixes are marked by an intentional excess of binder, and the draindown effect is caused by the impossibility of maintaining such an excess of binder on grains of aggregate. That problem is most frequently solved by adding a stabilizer (or drainage inhibitor) to a mix. Its task is to absorb any excess of binder.

Excessive draindown may be caused by several factors (as described in Chapter 4). Binder or mastic draindown from a mix brings about many problems; most of them are described in Chapter 11.

Research on an SMA mix’s susceptibility to binder or...

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STORM-WATER CALCULATIONS

Posted by on 16/ 11/ 15

Подпись: ✓ fast code fact Journeyman plumbers are not normally required to know how to figure roof drains and major storm-water calculations. This is typically the job of a master plumber. Of course, circumstances vary from location to location, so the process is well worth learning at any level in your plumbing career. Storm-water calculations stump some plumbers. I think that the problem for some plumbers is computing the amount of water accumulated due to structures on roofs. For example, if a roof has an enclosed stairway sys­tem, the walls and roof of the stairway have to be factored into the equation for what is required in rainfall drainage. Some plumbers find doing the math for roof drains, rain leaders, and other storm piping to be intimidating. Given the proper charts and tables, the job is not really too difficult.

Подпись: been there done that Don’t allow the code requirements to scare you. I remember the first time I had to pipe an island sink. It made me very uncomfortable, even though there was a diagram in the codebook on how to do the job. What may seem daunting when you first look at the code is not necessarily such a mess. Trust in yourself. I used to teach code classes for plumbers who were preparing to take their licensing tests. After teaching the class for a while, I noticed some common elements from class to class...

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Welded Steel Box Girder Bridge

Posted by on 16/ 11/ 15

The steel box girder bridge is depicted in Fig. 4.10. The steel elements are fabricated and erected as “tubs,” and the composite concrete deck is placed in the field. This con­figuration has some advantages over plate girder construction. Visually, it is “cleaner,” and it does not provide surfaces for birds to perch. For high-visibility bridges, such as urban interchange bridges where motorists are constantly passing beneath the bridge, the enhanced appearance may be a deciding factor. Also, the cleaner surface areas tend to improve durability and reduce repainting costs. The bridge is torsionally stiff—especially

Welded Steel Box Girder Bridge

FIGURE 4.10 Cross-section of bridge with steel box girders.

beneficial for horizontally curved bridges...

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Rafter Guidelines

Posted by on 16/ 11/ 15

There are calculators that are made specifically for assisting with construction math. These are very helpful in finding rafter lengths. Construction Master IV® is one available calculator, which we will refer to and use in this chapter to demonstrate the process of finding rafter® lengths. These calculators make it easy to do the complicated math, working in feet and inches. The sequence of buttons takes a little time to master, but once you are familiar with them, you will never go back to pencil and paper.

Learning by Example

The best way to learn cutting of rafters is to completely work through the actual process. The following example uses the diagonal percent method of finding rafter lengths. The example shows how to find the lengths of the parts of a relatively difficult roof...

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Toenailing

Posted by on 16/ 11/ 15

Carpenters need to know how to drive a nail at an angle. This technique is called toenailing and is often used to join pieces of wood that meet at a right angle.

When toenailing, you have to be careful not to split the wood, which is easy to do when you’re nailing so close to the end of a board. You can often avoid splitting the wood by dulling the point of the nail. Place the nail head on a hard surface and tap the point several times with your hammer. In­stead of spreading the wood fibers and splitting the wood, the blunt point will simply break the wood grain as it penetrates.

To toenail two boards, hold the nail at a 60° angle and start it about 3A in...

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