Thank you.
I should have also mentioned, if the bolt interface is properly designed (i.e. the bolt is in tension only, and never in shear), then the joint is rigid, and there is never any play. But on optical instruments I work on, I still insist on all bolted interfaces to have pins, because otherwise one unexpected (above design load) jolt can knock the system out of alignment.
Well, even in a bolted joint there will be a slight amount of “play”, and after initial relaxation of the joint (when the bolts and parent material undergo thermal hysteresis and equalization of any offset stresses) it may need to be retorqued to guarantee holding in very critical designs. I have used alignment or shear pins to resist shear in exactly the sort of system you describe where maintaining alignment is critical and the joint may experience high transient vibration or shock that could exceed the preload. However, from a design and fabrication standpoint is is a real pain because you have to assure almost perfect alignment of the holes versus the fairly loose tolerance of through holes for threaded fasteners or studs.
Stranger
no. The tallest building in the world is concrete.
These issues seem like things which could be resolved in the modern day, if some clever person came up with an automated riveter that heated and shot the rivets in a consistent manner, which could be moved and operated by a single person.
Business opportunity?
As a rivet cools, it contracts, pulling the join tighter.
There is a limit, though. If a uniform concrete pillar is too tall, then the weight of the pillar will exceed the compressive strength of the concrete and the base will crumble. The exact height limit varies a bit depending on the numbers you use for the density and strength of concrete, but when I did this calculation for my class a couple of weeks ago, it worked out to somewhere in the 800–900 meter range.
A tapered column can get taller because there’s more area at the bottom supporting the weight at the top. But the width you need grows exponentially with height (I think), and so eventually your column would get too wide at the base to fit on the parcel of land that you have.
Historical note here. I worked as a structural engineer back in the 50’s and 60’s, and even then riveting was so obsolete that it I don’t recall ever being on a design that specified its use.
For any steel fabrication, we used either welding or high strength bolts, never rivets. And this was 60 years ago.
A properly installed rivet completely fills the hole. A bolt requires a larger hole than the bolt itself. Under shear, each rivet will carry an equal load, but each bolt in a joint would move slightly to take up the slack in the oversize hole.
By the way, don’t they still use rivets for airplanes (including airliners)? Or are they all welded now?
For some aircraft skin attachment, a combination of rivets (for permanent attachment) and countersunk screws (for field removable or inspectable attachments) may be used, but for many modern aircraft skin is either resistance welded or bonder to stringers, or in some cases the section is machined from a billet with the stringers integral to the skin, and the entire assembly bonded or screwed into the wing or fuselage structure. In the case of composite structures the preferred attachment method is adhesive bonding.
Stranger
lol
Note that typical rivieted structures had a more rivets, and typical bolted sturctures have fewer bolts.
They are doing different things, but also the metal they are attached through is different: those old structures the metal would torn or cracked around the rivets if there were only a few large rivets, even if the rivets themselves had been strong enough, and the joint itself had been rigid enough.
New steels made it possible (economic) to bolt steel structures.
Back in the day, when I used to do steel erecting, I can remember getting really pissed off at a site engineer who took me to task for cutting a few bolt holes in an I- beam with an oxy-acetylene torch rather than using a drill.
My torch skills were exemplary, the holes were neat, the bolts were not critically load-bearing, using a drill would have been a real PITA … but even after I explained all this to him he still insisted that they should be drilled.
Needless to say, I waited until he was on his lunch break and torched them anyway.
That was like almost forty years ago, and the building still hasn’t fallen down … I drive past it every day.
One of the things I learned on the Dope was that bolts are not meant to take shear loads despite advice to the contrary from long ago. I believe I had misinterpreted some best practice advice that we intended to indicate that for safety horizontal bolting was preferred, probably to avoid nuts falling off (and nuts should always be on the bottom end of a vertical bolt so the bolt can’t fall out), and maybe to hold the shear load in case a nut does come off and there is no more compression to hold the pieces together. Since then I’ve seen aircraft shoulder bolts intended to take shear loads, more costly as mentioned above.