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57

Screws are a "superior" fastener over a nail (they have far superior tensile strength) - especially if you're talking about screwing down decking. However there are many scenarios where a nail is the proper fastener for the application (attaching joists is one example - screws are brittle and will fail when subjected to the forces of a shear loaded ...


25

Nails are considered an "elastic connection". They handle wood movement much better than screws. Many times if you have severe wood movement with nails you will see things like nails that tilt or seem to back out. This is actually a good thing. Many times if a screw had been used in that case it would have caused the wood to split as it moved.


14

I'd go with @Aarthi's load bearing table resource for a general idea of what's reasonable. If you're looking for equations though, you can start with these: Beam Deflection Formulas Beam Deflection and Stress Calculator Area Moments of Inertia Using the Parallel Axis Theorem Wood Material Properties (Modulus of Elasticity (E) found in Table 4-3a) For ...


13

You asked for optimal: Follow a few thousand years of practical experience and put in a tension brace (lower outside corner to top hinge-side corner - opposite what you are going for, which is a compression brace) Go with the past few hundred years and make it a turnbuckle. The best form of compression brace "in plane" is none of the above, and has a point ...


9

I'm not a hundred percent sure this answers your question, but I will say this much: 300lbs is actually much, MUCH too low of an estimate, if all of my trolling on this site is anything to go by. Also note that it's not weight but force (ie Newtons) that you need to be looking at. Second, this document should answer your load-bearing questions. It's kind of ...


8

Technically when using joist hangers, a specific kind of hardened galvanized nails are supposed to be used. This is because regular deck screws probably don't have the necessary shear strength. For a deck though, I've used screws before without any problem. Although if you were planning to put a lot of weight on the deck (say, a hot tub) I would be a bit ...


8

Unless your holes match the bolt size very precisely (like, you have to hammer the bolts home), you will get racking, which will weaken the joint over time. Likewise, the bolts will loosen up (use lock washers and check it frequently). It's something you'll have to watch for; as the holes get stretched, you'll need to figure out what to do. Think about how ...


7

A welded connection can always be made the same strength as the original steel by using a full penetration but weld but this all depends on the quality of the materials used for the welding and the quality of the welding itself. Therei s a very good reason why there is a lot of non destructive testing used when welded joints are being used for structural ...


7

I found the following VERY detailed tutorial on determining joist span based on expected live and dead load: American Wood Council The weight your deck will need to support will depend whether you get snow and how much, whether there will be a roof over the deck, whether the deck will be sheltered by any other means, what do you expect to do with the deck ...


7

Nails are used in almost all framing and structural applications. Most code books are designed with nails in mind and will have specific minimum nailing requirements and patterns for different applications. Structural screws are coming more and more on the market every day, but because most code books don't include them you will need an engineer's approval ...


5

Static load affects structures much differently than dynamic (moving) load. A dynamic load will give periods of relaxation for members to return to their previous shape. A static load will promote bending. Considering the pressure and surface area, you basically need this to sit on your slab. The tank can't take pressure, and you don't want the tank pulling ...


5

Keep in mind that your load is not static, but dynamic, and the stresses will multiply during the movement of the swing. Also, the movement of the swing will apply stresses against the short dimension of the beam, which it was never intended to support. Looking at the swing sets available at building centers, I've never seen a main support beam smaller ...


5

There isn't enough information in that sketch to verify calculations (for instance, we have no idea what's on the floor above), but here are some reactions: Removing 60cm of support may be significant, depending on how much load that wall was carrying. If the arch is structural, removing it requires additional support. Your existing building may not be ...


4

This is a fairly complex problem to answer starting from scratch as it has multiple components so I will just summarise the calculations that will need to be done. In terms of the stresses in the plank, typically as a minimum you will need to calculate the following forces: Bending moments Shear forces Bearing stresses Deflections These will need to ...


4

Here would be my basic approach (Mechanical Engineer here, Statics TA for 4 semesters): For starters, you could figure out the weight of the mattress and box spring plus the weight of two people lying on it (W). Add in a safety factor (at a minimum 2, ideally a bit more) - remember, an uneven or dynamic loading will apply significantly higher stresses to ...


4

More or less a question for mechanics and machinists and an easy one. If you've ever busted a head stud off on a Jaguar, you know of the evils needed to get the remainder out of the block. Lots of methods out there, but aside from electrostatic erosion, most methods involve using a drill. This drilling machine is magnetic because the base is a very strong ...


4

OK first let me say that if you're going to be making major structural changes to a building (and this counts as a pretty serious structural change in my mind) it would be well worth your while to get an engineer or other qualified building professional to help you with your design. If you just "wing it" you may be endangering the house and its occupants. ...


3

I can't speak as to how to calculate it, but from experience, 2x4s are overkill. For the beds I've seen, 1x3s slats (laid down, not vertical), with a vertical 1x4 perimeter, were sufficient unless both people weigh 300+lbs. You will want a center rail and possibly a center leg (some mattress warranties actually require one!). Reducing the span length is a ...


3

putting the legs on the inside will induce a shearing load on the connection. A better connection would be having the wood frame rest on the leg (with a notch). You also need to account for the needed strength in the corners so everything stays square. or you can do a google search on bed plans and get a tried and tested design the first link even only ...


3

Screws would tend to be slightly thicker than nails (because of the threads) so you would probably want to watch out for splitting of the wood and might want to require drilling pilot holes if you switch to screws. For the most part though, screws would work better than nails in the long term (would not pop up over time) but would be harder to use (pilot ...


3

One thing that no one has mentioned: screws WILL NOT pull down a deck board nearly as tightly as a nail. If you have a twisted board or a board with a crown, a screw is pretty much useless. Screwing deck boards also creates large holes for water to soak into and rot much faster. Using a 3 inch galvanized nail and nailing it flush will pull the boards ...


3

Normal Vibrations in Buildings Have Identifiable Sources I've encountered a vast range of vibrations in multi-dwelling buildings I have lived. Hear are the ones I can remember: washing machine spin cycle (this happens often and, if it matches the resonance of the building can travel throughout multiple floors) dishwasher valves and drain pump (not very ...


3

You could truss the tubes as shown in the picture below. The center block helps to support the tube when the truss member is placed in tension. The truss could be constructed from heavy wire or threaded steel rod. The concept here would be similar to the scheme used on the wider steps of a wooden step ladder. I would have suggested the possibility to ...


2

A general rule of thumb is use screws when you need pull strength and nails when you need shear strength. For example use a screw to hold down a decking board, but a nail to hold the joist up. Screws hold thing tighter then nails, but screws are brittle when hit from the side giving nails the advantage. This is not a hard fast rule, but covers 90% of of ...


2

If I understand the question, it sounds like you're asking how to keep a glass greenhouse cool in the desert. That a daunting task and, well, seems a little impractical. That said, some ideas: make the roof openable/retractable be sure to allow for lots of cross-ventilation (side windows/screened in) block the sun curtains awnings curtains put the ...


2

There is an online calculator called the Sagulator that estimates the deflection in a shelf given its dimensions, the type of wood, and the load.



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