E_I,

You are forgetting factor of safety. If you design to absolute smallest cross-section required under any of the equations, you leave yourself no room for material deterioriation or damages that may occur over time. Why would I use a 12x16 or a 12x18 or 12x20, in case there is a fire or other damages or deterioriation, there is a chance that there is enough material remaining to be able to use the beam vs. possibly tearing down a building altogether and start all over. Also solid hewn timbers can not be guaranteed throughout its mass to have Structural Select quality throughout. It'll vary in grade. (hence quality and material properties). 

Yes, I do know about LRFD. It begins on page 51 of the book "Simplified Engineering for Architects and Builders" 11th edition. (I can't guarantee page numbers for other editions.

I typically use the Working Stress method. Then size up a notch or two is the sizes of members. Building requires performance based design to be equal to or superior to the performance standards outlined in prescriptive path. These deflections limits under designed loads are in fact a performance standard. I sometimes go above and beyond that. It comes down to what risks are you willing to accept. There is always risks.

AISC is about steel. LRFD is appropriate for products like steel where there is guaranteed attributes for the material being equal to or greater than that of the rating. Wood varies and therefore properties are likely not stress tested prior to being shipped. One reason I don't design on assumption of structural select in large timber beams is that condition almost doesn't exist these days because the trees aren't harvested at the 300+ year mark where the trees have a large enough diameter of harvested logs that there is no knots or other imperfections (that also reduces strength) throughout the entire cross section. It is possible with a built up beam but you need sufficient bonding of each ply of lumber used so the bonding point is not weaker than lumber plies that makes up the beam. The problem in a field built-up is there is usually a strength reduction factor and I have to increase for. At that point, it's probably easier to use a Glulam that's pre-engineered. With solid timber, I treat it on average as a #2 grade throughout. While, I can specify #SS or #1 & Btr grade but it's better to design with a lower grade in consideration.

These are methods of addressing factors of safety that I take into consideration. 

In any circumstances, I can use either method. I can use LRFD method and then the factors of safety is up to me or I use the ASD method and its factors of safety plus any additional factor of safety I am comfortable with.

I design with some overloading being factored in and still have performance meeting the code. 

I'm not always designing for cheap. One reason John Wick's buildings hold up for this long is that principle. There's the old saying "hell-for-stout". 

btw, Richard somewhere above you wrote L/180 for the proposal of (2) 2x12s in the original sheethingless scenario. thats actually about right. as a BOT, do you even read your posts? did you forget that you actually confirmed my calculation that you say later is wrong.......fail

Olaf,

Ok but you failed your specification of l/240 unless you are using Ipe or something like it. 

Poor Kevin2 just wanted to know how to get a contractor's license.

tduds,

Yes but some wants to pick fights with me. They don't get the idea of just don't. I can keep fighting until the ends of time... can they? 

jla-x,

Claims well paid contractor won't read plans...expects strangers to read long posts about Theodolites for free. 

How many of you are dangling on a roof (6:12, 12:12, whatever) in 90+ degree weather while being on this forum?

How many of you are in an air conditioned cozy office in a cozy chair when reading on a forum? 

Who do you think I will have more sympathy for?

tduds,

The foreman would be right outside directing the framers, right? Not in a job trailer.

Humans have legs and are known to move from location to location as the need arises.

tduds, you don't supervise and direct construction from inside a plywood box.

It might not be the most current edition of that book but the equations hasn't changed. 

You do realize that these equations don't change that much. Not in 5 years. Sure, there are newer editions because they are in business to make new editions regularly. Book authoring/publishing business. 

Don't surprise me any.

Because someone asked for advice, and you rolled in claiming a contractors license cost 100k.  If you stop posting lies and bullshit, or better yet stop posting completely, then you won't get "attacked"

Dangermouse,

You are lying. I never said that is cost $100K to get a contractor's license. The $100K comment was being facetious and it had nothing to do with contractor license. 

E_I,

I said "SUBSTANTIALLY THE SAME". Do you know the difference?

E_I,

There hasn't been a revolution in physics understanding as used in engineering that would change the equations in any major way.

If the equation was scientifically correct 10 years ago, why would it not be in 10 years without a revolutionary breakthrough in physics.

no_form,

This professions changes a lot slower than the computer industry. That is why I doubt the equations changed in any significant way. If I plug in the equations under LRFD method of design, and computed for beam sizing, the values I will get will be about the same as the current edition. I bet the equation would be about the same as they were in the 1990s. 

Engineering calculations do not undergo revolutionary changes. That's not how science works. The last I recall, we haven't had a revolution that would change how we understand newtonian science.

The equation for uniform deflection and numerous other kinds of deflection of wood beams (for example) has not changed since the 19th century. 

The equations are the same equations. Not just similar. It is mathematically the exact SAME equations. They might change the some of the equation symbols and what they look like but when you know what the symbols mean, it is the same equation. The structure of the equations had not changed in over 125 years.

People familiar with newtonian physics understood newtonian physics the same as we do... especially as far as it is understood in engineering.

Olaf,

a blade harder and more durable than Ipe like a diamond tipped saw blade. That'll work. My rock cutting saw would do the trick.

You picked 4 architects (most of whom are not architects in the U.S. whose day job is probably a professor at some University because in their country, they can't get regular work. They practice architecture as hobbyist/artist not as a real full-time career. They don't work on real-world projects for real world people. They work for 'plastic' people who just wants some oversized art piece and to them, it doesn't matter if it is functional. 

Most of their designs, is eye candy but most part non-practical in a real world setting.

They are out of touch with what of touch with what people who uses the buildings wants. 

Most of us, I hope, are in the profession for a real world, serious, down to earth, career. I'm not in it to create a supersized coral reef on land. I design projects for people who want something realistic, within means. You tell me how in hell are we going to build something that looks like a coral reef in Astoria or other small towns. This shit has to be built like from a 1000 miles away and shipped to location. All of which contributes to environmental problems like global warming. 3d printed structures often using some kind of plastics (which is an oil based product) also is further application of using fossil fuel that isn't exactly that renewable.

I can probably design some structures using a lamella roof system but I have to look at cost factors and available skills. It is possible that with some effort and guidance, trades can learn how to make lamellas. There is nothing in the law that prohibits it. It is that you need the right kinds of buildings and roof form for such a roof to make sense and a budget that would support it.

Very seldom can any building that uses non-conventional components and structural systems ever be less expensive because it cost more on the labor and you don't usually offset enough on material cost to compensate for increased labor.

The majority of architects will continue to use conventional systems and conventional materials and largely conventional approaches.

Avante Garde architecture is something that will always be a rarity. Unless someone wants to explore that realm, you are not going to see a lot of that.

Builders costs more if you ask them to do more than conventional. 

Frankly, there isn't much investors investing in 3d printing for entire buildings or components. Until they have volume on equivalent level to plywood and lumber, I doubt they will be competing on the majority of commercial and residential projects.

There is certainly a lot a person can do with lamella roof systems, for example, but you need the right projects for it. It would be a remarkable project if I were to use a lamella roof on say a custom home. It would be something very few even know. In real world, this lamella roof I am talking about would probably be fantasy and whimsical dreaming unless someone was to give that much free reign to design and explore new form.

It would be awesome if a real project can have that opportunity. Most of us on any side of the licensing laws will never have that opportunity. You almost have to be rich and come from the social elite class to be a starchitect. You have to be a starchitect to have that kind of creative freedom. 

Fantasy aside, the real world isn't that open to explore new ideas like that. Most of us, have to be real. This is why many long-time basic methods of construction and materials are used, still.

You point out examples that represents maybe 0.1% of architecture built today.

Its like all these fantasy school/studio projects.

.

These four firms put together have literally billions of dollars in real projects on the boards at this moment.

I can design a 10,000 sq.ft. house with a 15,000 sq.ft. library to hold the building plans and specifications that would cost $10 TRILLION dollars. So fucking what.

What's this fascination of how many dollars spent on construction. It isn't the point. Who gives a fuck about how many dollars is blown in overspending. How many Billions of dollars do you con people into spending so you can get a bigger kickback out of the cost of construction. Yeah, I can be wasteful by buying the most expensive materials ever and inundate them with 1 MILLION 36x48 sheets of drawings and 100,000 pages of specifications so they have to build a library just for the plan and specifications set. Lets not forget also making sure the city building department has enough space for the two or three sets of all that that is to be submitted. Sure, if I want to be a real dick to a client, yeah... no problem. LOL!

Seriously, how much money spent on construction costs doesn't impress me one bit.

You can spend billions of dollars and have great architecture or billions of dollars and have utter shit or anywhere in between.