Today’s lecture will focus on tall buildings (both steel...

3

Today’s lecture will focus on tall buildings (both steel and concrete) through the works of Fazlur Khan (FK)

Before there was almost no collaboration between engineers and architects (e.g. Isler);

Also the structural artists that we have examined thus far typically worked with one material (concrete or steel); Khan worked with both.

We will look at, for the first time, an intimate collaboration between architects and engineers that led to structural art and quite fairly architectural art as well.

FK could not have done these buildings without collaboration with architectural partner

visual result = example of structural art

This was possible because he worked with architects, two in particular, who were interested in structure and expressing it. When we were studying bridges, it was appropriate to talk about engineers only, but when it comes to buildings, architects that collaborate with engineers also need to be discussed because they help create these structures

5

-The idea of structural expression in buildings can be dated back to the Gothic cathedrals

-Louis Sullivan’s Wainwright Building in St. Louis, 1890-91

-Sullivan –went to Paris at same time that Violet le Duc was there (absorbed ideas); was part of the first Chicago school which included John Root

-Same idea that structure plays some role

-Expressing tallness/height

-Every other column is nonstructural

Another Chicago school in the mid-20th century was influenced by the 1st Chicago school.

Brunswick building, that we will look at in detail later, is an example of its work.

See the expression of verticality.

All columns are “real” in this case, which requires a large transfer at base. However, in Wainwright every other column is not real (those that do not continue all the way to the ground; there is no column transfer there)

Again, will discuss in detail later.

brunswick image: David Billington

Wainright image: Reading Tom, CC (Attribution)https://www.flickr.com/photos/16801915@N06/5946078387

5

6

•Brunswick building is early example of Graham and Khan work

•First two men are architects who worked closely with engineer FK


7

Myron Goldsmith – studied under Mies van der Rohe – partner at SOM – never studied structural expression but keen on the idea. He also taught with Khan at IIT (for 22 years) and we will see how the research that they did with the graduate students manifested into real buildings with innovative structural systems

Inspired by the pioneering work of Italian architect and engineer Pier Luigi Nervi, Goldsmith received a Fulbright grant in 1953 to study with Nervi in Rome. After returning to the United States in 1955, Goldsmith joined the San Francisco office of Skidmore, Owings & Merrill. In 1958 Goldsmith transferred to SOM's Chicago office and became a partner in the firm in 1967

1944 he joined the Army Corps of Engineers.

Master's thesis at the Illinois Institute of Technology (formerly Armour Institute of Technology) was about tall buildings.

Had a professional license in both engineering and architecture and although he distinguished himself as a master of both architecture and engineering by nature he identified himself as more of an architect.

image: http://lynnbecker.com/repeat/goldsmith/goldsmith.htm

8

• Bruce Graham – architect – influenced by old chicago school

• Leading figure in SOM (largest architecture-engineering firm in the country at the time)

• He received his bachelor's degree in architecture from the University of Pennsylvania in 1948. After graduating, Graham worked for several years in the Chicago architectural firm of Holabird, Root & Burgee. In 1951 he joined the Chicago office of Skidmore, Owings & Merrill as chief of design and was elected a partner in 1960. Graham became a specialist in high-rise corporate structures, designing skyscrapers and office complexes in Chicago and worldwide.

• In the 1950s – Khan gained attention and respect from Graham – they worked together until Khan died in 1982 “we worked in tandem until at the end we could almost think for each other”

image: Source Unknown

9

•FK – central figure in this lecture

•born in Bangladesh 1929

•graduated first in his class (Bengal Engineering College 1950)

•went to University of Illinois at Urbana-Champaign on a scholarship

•PhD in 1955 then worked at SOM in Chicago until 1957 at which time he returned to Bagladesh for 3 years (terms of his scholarship). Then he returned to Chicago again (SOM)

•Goldsmith and Graham were the two most important architects that he worked with

•image: Yasmin Khan

10

First building in sequence of Khan and Graham is Inland Steel Building (1955)

-influenced by works of the First Chicago School

-Graham wanted to put columns outside the building envelope; structurally a challenge and he was looking for someone to do it

-Khan said he could do it (Graham didn’t know Khan well then) and from then on worked with him

Curtain wall is separated from column – tricky connection (form was Graham’s idea)

image Inland: Maria Garlock

11

Graham: This was where Faz first worked with me. He was a young engineer, still working only in the summer. Nobody in the office could figure out how to make the joints in the steel beams and the columns. In other words, if you have a steel beam and a steel column, how do you take the moment connection? Faz figured it out, he was the only one who had enough mathematics. He had a doctorate, you know. No engineers in Chicago had doctorate degrees. None. Faz figured it out. Andy Brown, who was then chief engineer, approved it. That was the first time I worked with Faz, but it wasn't that close, because he had to go back to finish his degree.

He already was a computer genius.

Blum: He served as a consultant?

Graham: He was employed part-time. And then he had to go back to the University of

Illinois for a while to finish his doctorate. I don't remember the exact amount

of time that he was gone.

image: Maria Garlock

12

Social:

Concerns with society needs in an urban setting: economic constraints

The reason that these buildings can become structural art is that they are development buildings (not corporate buildings by a client that wants a headquarters…)

Therefore the project automatically starts under a rigid budget that is set by the developer who hires the builder or construction manager with these budgetary constraints. The designer is then selected at about the same time.

With a corporate building, typically a star architect is hired who hires an engineer and then a contractor is selected. Not so tight budgetary constraints. Their building is a kind of marketing tool.

Khan searched for economy not only by minimizing materials, but also through consideration of construction practices.

He had a builder’s mentality

Symbolic:

Most buildings are architectural art because the structure is usually hidden behind the façade, but even though architects were involved with the design of Khan’s works, it is the expression of the structure not covered by a façade that makes their works structural art.

FK: “The social and visual impact of buildings is really my motivation for searching for new structural systems” and to get the right visual impact “a building’s natural strength should be expressed”

12

13

what is a structural system?

Myron Goldsmith, for his master’s thesis at IIT drew this sketch of bridge structural systems that represent the longest spans of each type at the time (1953): Humber, Quebec, etc.

As the spans get longer, it is time to go to another bridge system

It is the same with buildings… as the buildings got taller, it necessary to find a new structural system to achieve efficiency and economy.

image: Myron's thesis: "The Tall Building and the Effects of Scale”

• have the shear wall frame set up in class before it starts

• shake it

• remove the walls (ask class what they think will happen); shake it

• set up the moment frame; shake it

• remove the lower clips (ask class what they think will happen); shake it

Images: Maria Garlock

14


15

Bracing elements, expressed in some buildings and is not in others.


16

Which frame is NOT stable?

https://www.polleverywhere.com/multiple_choice_polls/hm2emex4Qis8H9B

17

Every floor has to have some type of bracing (not even necessarily symmetrical)


18

19

•FK developed the concept and details for many of these systems.

•For this class, it is beyond the scope for you to understand each one… just know that several types exist.

•He qualified them according to building height… this is an image taken from a paper that he wrote.

•In buildings these systems are often hidden from view and this makes judging buildings as structural art a challenge/difficult/impossible in most cases.

•We need to have the structural system in tall buildings exposed to be able to make a judgment.

•“While many tall buildings have structural elements exposed on the façade, not all of these buildings are structural art. Works of structural art not only expose structure, but they express the behavior of the structural system so that a visual analysis of the building helps to explain its structural behavior.”

•At the time that Khan began designing, all tall buildings were of the rigid frame type (explain).

•Khan showed that beyond 20 stories (or so) cost increases rapidly with height, therefore needed to develop a more appropriate structural system.

•First one we will discuss is the “tube

•“I believe that the building of tall structures simply for their own sake does not make economic sense, nor does it enhance the total environment of our

cities. It seems meaningless to develop structural systems for high rise buildings if the result does not have a positive effect toward creating better cities and better environment”

•image: redrawn by Tracy Huynh

19

Let’s say a building has 4 walls, but those walls are not connected and wind comes in, we see that those walls are quite flexible and can’t really resist the wind.

Image: Khan, Yasmin Sabina. Engineering Architecture: The Vision of Fazlur R. Khan. New York : W. W. Norton & Company, 2004.

20

But if you were to connect these walls at the corners (it will use the same amount of material), all 4 walls will work together to resist the wind and make up a more rigid structure. The thing about tall buildings is that it is not solely about how strong your structure is, or can it withstand wind loads; super-tall buildings are usually controlled by serviceability: how far the building is deflecting, how much are the accelerations at the top; because if it is deflecting too much, doors in the building may not be working well and structural elements might be cracking, and if the accelerations are not right, you might have people at the top of the building getting nauseous all the time. So, oftentimes, it is not just about strength but also about stiffness, and the taller the building, the more control serviceability will have over strength of the building.

21

Now, let’s take this concept of connected walls and grow it and make it taller. Take a big, tall, concrete tube.


22

You can’t just have a tube with solid concrete walls; you need doors to get in and windows to let light in so you start punching holes in the tube.


23

Perforate the tube to let light enter the space.


24

You can make windows even bigger.

Framed tube is then this idea of a tube with perforations for windows. And these perforations lead you to a system when beams and columns work together to resist lateral forces due to wind or earthquake.


25

26

Dewitt – Chestnut Apartment Building (completed in 1964) 43 story, 394 ft

first example of tube

not so interesting visually although more or less integrated

with Bruce Graham

Reinforced concrete

-loads were dumped to the outside

-get gravitational loads on the outside so the wind load effect is negligible

Like a wall with holes in it

Development building, work with a rigid budget

can’t see that columns actually get lighter as one goes up

image: SOM

North Lake Shore Drive Apartments by Mies Van der Rohe

-Derived architectural form from structure, yet most of it was a fake representation of structure.


27

Chestnut-DeWitt was visually distinct from the Mies buildings, yet “rhythmically” similar… articulation of structural grid, but without little I-shaped mullions (as in North Lake Shore Drive Apartments).


28

29

In FK’s building, we see that every other load carrying column discontinues when they hit a beam that continues into more broadly spaced bottom columns. The loads that the discontinued columns carry gets distributed between two bigger, bottom columns that further transfer loads to the foundation of the building.


Inside of an apartment

image: Maria Garlock, BUT don’t distribute. I cannot remember the name of the person who invited us to her home and I don’t want to distribute without her permission.

30

image: Maria Garlock, BUT don’t distribute. I cannot remember the name of the person who invited us to her home and I don’t want to distribute without her permission.

31

32

Traditionally, columns are dispersed inside and outside the building. What is shaded as yellow in these pictures is the core of the building, where you have elevator shafts, stairs and services; essentially the center of the building (every once in a while you may come across buildings where the core is not in the center)

However, pushing material (columns) to the perimeter is more efficient: more stiffness, less stress, avoid designing for wind stresses. Also there is less clutter in rentable space

33

Brunswick building (1965); Khan designed it before he designed the Chestnut DeWitt building

Early collaboration between SOM high-rise pioneers Bruce Graham, Myron Goldsmith, and Fazlur Kahn. For the Brunswick Building, Khan conceived a first-of-its-kind concrete tube structure. This innovation enabled the modular approach to high-rise construction later used on the John Hancock Center and Sears Tower.

Apt building/office-apt building – this plan was an architectural project

Initially, the idea was to build walls on the inside that would resist wind loads, but Khan figure that if you make outside columns closely spaced, that will have some kind of effect in controlling wind loads.

but closely spaced columns are not good (architecturally) at ground floor/lobby/entrance

need “transfer girder”

explain transfer girder

the form is the structure – transfer girders

image: David Billington

33

Even though the Brunswick building was completed in 1965, one year after Chestnut-DeWitt, the design for the Brunswick came first. During 1961 – 1963 he was concurrently developing the framed tube structural system, which he would initiate in the Chestnut-DeWitt Apts (He believed that tubular behavior depended on even closer column spacing than the Brunswick.)

Led by chief architect Bruce Graham and senior designer Myron Goldsmith

At the time, concrete construction was less expensive than steel construction per unit floor area

Khan was still a young engineer and new to the office but was given the responsibility for the design as project structural engineer

Khan perceived that the relatively close spacing of the columns (9’-4”) would influence the structural behavior of the shear-wall-type building.

This 37 story building may not impress onlookers today as particularly tall, yet at the time, few reinforced concrete structures reached 30 stories.

Compared to Chestnut DeWitt, loads from more floating columns needed to be transferred to the bottom columns in Brunswick Building.

Chestunt image: Maria Garlock


34

35

The architectural design of Brunswick building called for the elevation to correlate with the façade of the Chicago Civic Center, across the plaza (now the Richard J Daley Center).


transfer girder – disintegrated form

Worlds largest concrete girder (8 ft x 24 ft); 2 stories deep

heavy girder at base – 24 feet deep

thin columns – clunk onto heavy beam

clearly separate pieces

Khan dissatisfied; wanted to find a more fluid means of transferring loads

both images: Maria Garlock

36

Image bottom: source unknown

37

38

-reaction to Brunswick - “clunky”

-another example of a transfer girder: Walker in Houston Texas (also called 2 Shell Plaza)

Two Shell Plaza Houston, Texas

Collaboration between Graham and Khan

1972 completed

341 ft (104m); 26 stories

-explain gravity load path in picture

-In the middle of city

-Integrate beams and spandrels to make a frame

-this is integrated with façade

-Controlling flow of forces through the structuree: gradually transfer loads to main columns

-two shell image: David Billington

image right: Maria Garlock

39

It is a series of haunched beams: haunched beam is when the beam gets deeper as you approach column connections (down to the bottom). This was a new way of transferring closely spaced columns into broadly spaced columns at the bottom.

sketch by Razvan Gilic-Micu

40

41

Marine Midland – Rochester, N.Y.

-can’t see transfer because it is integrated in the façade

-columns are wider and deeper at the supports

More integrated transfer girder

undulating

columns get heavier towards support

2 shell – increase area by widening

Marine Midland – increase area also by deepening

marin midland image: David Billington

42

-distance of Marine Midland

-it is an arch (or fan) with vertical members (columns) that draw load to columns below

marin midland images: David Billington

43

-Khan’s slide when he gave a lecture at Princeton- on the left of the sketch - dull typical buildings

-Khan wants a form to control the force, he does this by varying the form of columns: as columns get heavier they attract more load

Only thing possible is opening space at base with transfer girder

express this as shown on right.

sketch: Fazlur Khan

44

- see undulation in the façade

-owner hires builder or construction manager first and then designer

-columns could have been made entirely by widening

But here, Khan both widened and deepened (undulating) them

perfectly rational


45

-scale factors - light columns carry almost no load (because force is attracted to stiffness)

The name of the building might have changed

image: David BIllington

46

Overly simple idea of transfer within the façade:

-make form so that function (forces) follow it

Imagine there are five columns, each with equal load P, and there is a beam that can’t rotate but can only move down horizontally.

Once loads are transferred to the beam, more force will go to the column with bigger area and smaller force will go to the smaller area (load willredistribute itself).


47

Think of main columns as a series of springs on a rigid beam. The bigger the column the stiffer the spring it represents, and force it be attracted to the stiffer path. In the end, when the forces are redistributed among the main columns, the stiffest one (yellow in the center) will carry the biggest load.

Khan used this notion of force following stiffer path to control force flow in his buildings.

48

-if you stand there and turn around you see…


49

-Xerox headquarters; on the right, to show the contrast between structural and architectural art.

-irrational structure

-does not fit in our concept of the structural art

-costly

-transfer girder not integrated

-not a development building (a headquarters) wanted a dramatic form

While Marine Midland is a structural art because it expresses structure in an elegant way, and the structure was designed to control forces. You can clearly see the structure when you look at the building.


50

-Turn around again (image on the left)

-spread out - actually not rational since it is not very tall (~ 20 stories)

-a game being played to make it look functional


51

The building on the right is Rainier Tower ((Minoru Yamasaki with NBBJ, 1977), Seattle, 1977

-high-seismic region (not rational)

-example of perverse design

-visually we can’t see how the building will resist earthquake if it comes; not dangerous, but expensive

Image: Rainier Tower ((Minoru Yamasaki with NBBJ, 1977), Seattle, 1977, Courtesy MKA (http://www.historylink.org/index.cfm?DisplayPage=output.cfm&file_id=9632)

Different ways that Khan came up with to transfer column loads. These all were possible because of Khan working with architects who were willing to embrace the idea of expressing structure (in a building not everything is centered around forces; there is a whole architecture program going on inside the building, and engineers and architects need to work in harmony to make a successful project).

53

Houston. TX


54

now come to different design entirely

-One Shell Plaza (Houston, Texas)

--tallest concrete structure when built (50 stories)


55

56

From afar, you can see some different strips on the surface of the building.

image right: David Billington

57

-again - see something is going on


58

When you get close up, you see columns protruding: the come out of the surface and the go back in, the come out and go back in again. This is happening because Khan is making those columns bigger; instead of hiding them inside the space, he is pushing them outside the space. And the reason for making these columns bigger is to control creep.

To understand what it is about, let’s look at the floor plan,

image David Billington

59

-1/4 of floor plan

-at corner - the one-way systems become a two-way system

-at intersection - heavily loaded girders and heavily loaded columns - columns need to be bigger

-choosing between making columns wider or deeper or deeper towards interior/exterior

idea = get gravity load on outside or core (no columns in between, so the load gets distributed between the core and outside columns)

Khan and Graham wanted to express that something was going on by pushing deeper and wider columns outside


Colors on the inverted waffle grid on the right match colors in the scheme on the left.


60

Structural analysis by CEE463 students revealed that the columns that Khan made bigger are the columns that carry the most of the load, so in order to prevent too much creep, he made those columns bigger in area. He could have added more reinforcement steel or done many other things, making columns bigger in size is the best way to control creep.

Image: source unknown

61

62

Because of height and foundation issues it was built with lightweight concrete (less dense for almost the same weight)

Concrete = mixture of cement, water, sand, aggregates

Light weight concrete uses processed aggregates that are more porous and cellular.

Structural lightweight concrete has strengths comparable to normal weight concrete, yet is typically 25% to 35% lighter.

Lightweight concrete – need to consider creep effects (more of a consideration than normal weight concrete)

1st high rise building to do a sophisticated creep analysis

Increased the column size to eliminate differential creep

creep = 1.2 to 3 times the instantaneous deformation over 2 to 5 years and is proportional to the amount of applied stress

creep is more significant in lightweight concrete, partly due to the outward migration of pore water which evaporates into the surrounding environment


63

-One Shell Square - designed initially by Graham and Khan

supposed to be a tower in New Orleans (was not selected)

explored this in concrete

Not a wall punctured by holes but a truss (X-brace) with light walls behind it

Studied by a student at IIT with Goldsmith and Khan

image: source unknown

64

One shell square – this is what was built instead of the concrete x-braced system

New Orleans - building was supposed to be in x’s but really a composite

no real visual interest (not bad) except how it was built and designed.


65

Composite construction:

You build about 8 floors of steel frame only, and then concrete follows up after. Essentially, steel acts as a scaffold to hold the concrete, and when the concrete comes up, you build another level of steel.

image: Paper (source needed)

66

-steel – scaffolding for concrete structure but also part of final structure

steel does not carry concrete loads above

once steel is up, concrete is poured

steel is small part of the structure

image: Khan, Composite or Mixed Steel-Concrete, pg. 88

67

-see it going up

image: Khan, Composite or Mixed Steel-Concrete, pg. 89

68

-construction drawing – top image is an elevation view:

you have a steel column shaded with orange and a steel slab extending to the right, and then you pour concrete to make a concrete column and a concrete slab

-bottom image: plan view:

steel column (again in orange) and concrete column is shaded with yellow

-has become a standard method because of the designer’s mentality

concrete column is much larger than steel column used for erection

steel columns become reinforcing steel for exterior concrete columns

Image/diagrams: Source Unknown

69

-see outside of it

most tall buildings are built this way (composite construction)

Was tallest composite building when completed in 1972 (212m, 51 floors)

Image: David BIllington

70

image: Fazlur Khan

71

-Proposal for One Shell Square was not accepted

studied by student at IIT with Khan and Goldsmith

After Khan’s death, accepted in New York City - Wang Building (780 3rd Avenue)

1984

-idea – framed tube with punched holes (perforated) for windows but filled in some of the windows with concrete. Designers filled in those holes so that it created a bracing on the structural form, which provides an enhanced structural response to wind loads and seismic loads.


72

Some windows blocked out to make diagonals. You might mistake dark regions on the left image for shadow, but that is actually a granite facing of the building


73

-reflect X-bracing

granite façade but still retains X-bracing expression, although it is sometimes hard to see because of the darkness of granite

building is narrow, so it needed a bracing system


74


75

In this image, it is actually hard to see the X-bracing, and it looks more like a random filling in of windows. You really have to step back to see the pattern on the surface of the building.


76


77

-Left a similar building on drawing board when he died (1982)

-Onterie Center was not designed by Khan but designers credited him (oversaw conceptual design)


78

-filling in the windows

light columns

no façade on this one

But notice how the color made the bracing pattern obvious, while on 780 Third Ave. it is barely recognizable


79

-diagram of one block (panel)

add steel reinforcement to run diagonally through the panel. And the steel is spliced (steel cages coming and integrating themselves) at the darker points in the drawing

sketch = source unknown

80

-Onterie Center under construction

-Hancock in the background

man is 7 feet tall

see reinforcement pattern (steel cage)

Image: David Billington

81

-the way the building looks in the landscape

-insistence of the X’s

-collaborative design that expresses our ideals of structural art

Notice that X’s in the Hancock Tower are not visible from afar (meant to be seen from close up whereas others are meant to be seen from a distance)

Onterie is close to H.T.

image: SOM

Competing is in human nature, and if we look at the tallest buildings in the world built at around that time they were all in steel and the US was dominating in this competition. Notice the evolution of the building structural systems throughout this competition. But then, we see a change from steel to concrete, we moved to a new structural system (core + outrigeer) and the tallest building are now built mostly in Asia

image of graph: redrawn by Tracy Hyunh (original source = can’t remember!)

82

When we look at the same type of plot for buildings we see a huge jump (just like the GWB) in case of Burj Khalifa, that was designed by Bill Baker (interestingly) of SOM. This building just blows away all the tall buildings that came before itself. It got the title of world’s tallest building not by exceeding the record just a little, but by exceeding it by a lot!

image of burj: Donaldytong, GNU Free Documentation License, https://en.wikipedia.org/wiki/File:Burj_Khalifa.jpg

83

Burj Khalifa in comparison with world’s other tall buildings. We will learn more about Burj Khalifa in upcoming lectures.

sketch: http://www.tlarkins.net/stuff/places/dubai.html

84

Image of Khan on the left (who worked in SOM) and Bill Baker (also of SOM) who continued SOM tradition of innovating in form and design.

image of Khan: Yasmin Khan

85

Today’s lecture will focus on tall buildings (both steel...

Documents

Transcript of Today’s lecture will focus on tall buildings (both steel...