meticulous architecture

Adobe walls, 18" thick.

Office space alternative to lease or rent?

Modular ratio (n), a ratio of the moduli of elasticity of different materials to determine bend strength of two different materials such as a composite beam; e.g. W shape with concrete slab top flange.

Examples:

n = E_s/E_c
n = E_s/E_m # E_s steel, E_c concrete, E_m masonry

What are the three laws of equilibrium with regard to any structural member?

Σ ↑ = ↓ # vertical forces
Σ ← = → # horizontal forces
Σ clockwise = counter-clockwise

If these equations can be solved, beam is “statically determinate.”

strain = D/L
deformation under axial load (as below)

Strain, deformation of a member resulting from stress (unit deformation), can also be written as

s = e / L

s strain
e dimensional change
L original length of the member

Anderson Marsh State Historic Park (SHP) has an old ranch house that I am looking for...

Someone from the business world called and said industrial gross (IG) is a lease agreement where the landlord is responsible for real estate taxes and insurance, while the tenant is responsible for utilities, janitorial and items inside the building. On utilities in office buildings that have adopted this arrangement, sometimes the landord installs separate meters or he or she might charge a proportional share of charges incurred on meters for all or parts of the building.

This reference gives a mind-numbing array of leasing terms, and dances around IG. An East Bay reference spells out IG substantially as above.

“Greenspirit - Trees are the Answer” is the title of an article someone from another state sent. The article is a powerful argument against burning fossil fuels, building parking lots and monoculture forms of agriculture. The article also offers some ideas about sustainable forestry and increased use of wood for fuel, particularly in developing countries at no net increase in carbon dioxide emissions, and reduced use of fossil fuel, which represents more than 100% carbon dioxide burden considering the fossil fuels used in extraction and refinement. As to paper and construction the article recommends using wood, while reducing use of unsustainable concrete, steel and plastic.

ARE division statements, tasks and references

General Structures

Lateral Forces

STRUCTURES
GENERAL

Terms, concepts
structural elements
purlin: roof beam usu. @ truss panel joints to avoid bending stress in top
chord
pile cap: transfers column load to piles
forces
force couple = equal but opposite forces
double shear: 2 shear planes (places of poss. shear failure ) as in bolts
shear stress in column pad depends on load, column, size & thickness of pad
(not reinf. steel)

matenal properties
E = modulus of elasticity = stress/strain (Hooke's law)
E for steel = 29, 000, 000 psi
E for Doug fir = 1,600,000 psi
E for conc. = 57,000√f'c (-->ult. strength after 28 days)
for A36 steel, Fb = 24 ksi if compression flange laterally supported
fy = 40 ksi for grade 40 steel, 60 ksi for grade 60 steel
joist girder designation: 60G10N14.4K
60 in. deep, 10 eq. spaces along girder, 14.4 kip load @ ea. panel point
rules of thumb
structural costs about 25% of total constr. cost
truss depth to span ratio 1:10 best
slab on grade 3-1/2 to 9"
max slump
sidewalk conc.: 4"
min. conc. coverage
3" @ footings against earth
1-1/2" interior columns
3/4" @ interior slabs

Characteristics of different structural-systems
folded plate
inclined planes function as deep beams
pretensioning: steel tensioned before conc. cast
no end anchorages
consider shrinkage of conc. & creep of conc. & steel
continuous beams
less Mmax, deflection
Mmax greater in end spans than in middle
flat plate
use where loads relatively light
deflection high
flat slab
round column w/ capital, drop panel

formulas





stress = P/A (unit axial stress)
bending stress: f = M/S
strain = D/L
deformation under axial load
Δ=PL/AE
coefficient of linear expansion n (per 1 degree )
Δ = nL Δ t
Max moment
Mmax = w1**2/8 uniform load simple beam
Mmax = Pl/4 concentrated load at center

moment of inertia I (in**4)
I = bd**3/12 for rectangular section
neutral axis: y bar = ΣAy/ΣA
Ix-x = Σ (Io + Ayn**2)
section modulus
S = I/c (in**3) (c = dist. from outer fiber to neut. axis)
S = M/Fb (allowable bending stress)
Area of wood beam
A = 3V/2Fv (V = max shear; Fv = allowable shear)
Tu = Asfy ultimate tensile strength of rebar
Trig
sin 30 = .5
cos 30 = .866
tan 30 = .577
sin 45 = .707
cos 45 = .707
tan 45 = 1
sin 60 = .866
cos 60 = .5
tan 60 = 1.732
columns
round conc. columns reinforcement
spiral - stronger
ties
K factor in column design
accounts for diffs in column end conditions
Kx unbraced length = Kl (effective length)
steel columns
slenderness ratio = l/r (radius of gyration)
circle, tube - most efficient shapes - resist buckling; material far from axis
base plate
non-shrink grout (1")
Fp = 0.35 f'c
f'c = 3000 psi --> Fp = 1050 psi



A=P/Fp
Beams
Preliminary beam sizes
depth (in.) = 1/2 span (ft)
weight (lb/ft) = 1.25 W (kips)
delta = depth (in)/10
most efficient way to minimize deflection: increase depth ( -->I)
stiffness calcs to check for ponding - double deflections
short beams + long girders = less material but more depth
long beams + short girders = more material but less depth
plate girders
large load
large span ~ 100
depth 3 to 6'
web stiffeners
composite beams
large load, span
wide beam spacing
optional welded plate @ bottom
4 to 6" conc. deck
open-web steel joists
spans > 60' bolted bridging
LH for floors: 18-48" d, 96' 1
DLH for roofs: 52- 72" d, 144' 1
J series 36,000 psi yield strength
H series 50,000 psi yield strength chord sections
either hot-rolled or cold-rolled steel
underslung or pitched
designation: nominal depth @ center + size of top chord section (e.g., 40 LH
10)
often provided w/ top chord extended ends --> cantilever
other one-way flexural systems
channel slab
box girder
double T - most common
two-way flexural systems
1/12 - 1/20 span/depth --> shallower

connections
F - friction type
impact loading
N - bearing, threads included
steel binds w/bolt
X - bearing, no threads
bolts
A307 (120 ksi)
A325 (44 ksi) most common


welds
radiographic inspection (x-rays) used to test welds
strength of weld based on shear strength thru throat
fillet weld throat = .707(size)
Fsw = 0.40 Fy base material
Fsw = 0.30Fy weld material
avoid welding rebar

conc. systems
ultimate strength = 1.4 DL + 1.7 LL (factored loads)
balanced beam: designed for simultaneous failure of conc. and steel
under-reinforced is better - warning cracks
compression steel - can help reduce depth of conc. beam
in top portion of beam - tied w/ stirrups to lower reinf.
prestressed conc. advantages
fewer cracks
corrosive atmosphere
stiffer
smaller
kelly ball test - for workability of conc. - less common than slump test

Foundations
spread footing
wall, grade beam
combined
at property line
cantilever footing ( also strap footing) @ property line
mat/raft
good for differential settlement
moves up and down w/water table
pile footing/caissons
drilled pier - bell @ bottom for bearing

site constr .
excavation
footing 6" @ natural grade
6" below frost line
backfill
clean, low shrink/swell, compacted
std. proctor compaction test
95% bldg.
90% parking lots

History
Perret- first to use reinf. conc. frame in hi-rise
Kahn- struct. eng. on Hancock, Sears Tower
Jenney- first skyscraper - Home Insurance Co. 1883
Maillart - Swiss eng. - bridges


LATERAL

retaining walls
resultant should fall in middle third of base
usu. designed to resist 30 lb/cf pressure
counterfort wall: retaining wall w/ bracing walls

hydrostatic pressure 62.4 lb/cf - pools, tanks

seismic force
Richter scale - each no. is about 32 times previous no.
lateral force, or shear at base V
V = ZIKCSW or V = ZICW/R
Z = zone factor
zone 0, z = 0
zone 1, z = 3/16
zone 2, z = 3/8
zone 3, z = 3/4
zone 4, z = 1
I = importance 1-1.5
assembly of over 300 --> I = 1.25
essential facilities (hospitals, fire, police) --> I = 1.5
K = lateral resisting type
moment resisting frames
resists by bending
most ductile
steel or conc.
ductile moment resisting space frame
shear walls
allowable shear for diff mat'ls -- table 25K
stiffest
braced frames
seismic force is dependent on stiffness of structure
K value from table 23T
.67 --> 2.5
ductile --> less ductile
bldgs > l60'h in zone 3 or 4 must have DMRSF resist 25%
C = accel. = 1/15√T (period (sec.)) or C = 1.25S/T**2/3 (1991 UBC)
T = .05h/√D
h = ht. of structure (ft)
D = dimension parallel to applied forces (ft)
for DMRSF bldgs., T = .10ON
N = no. of stories
long period --> flexible, low force
short period --> stiff, high force
drift = 1/500 h
S = subsoil condition - betw. 1-1.5
max when Tbldg = Tsoil

firm soil --> higher force
CS < 0.14 per UBC
W = total dead load incl. partitions
storage & warehouse include 25% live load also
distribution of base shear
force applied to any level x
Fx = (V -Ft)wx*hx/Σwh
Ft = force at top = .07TV < .25V
diaphragms
rigid, semi-rigid - transfers loads in proportion to rigidity of verticals
flexible, semi-flexible
drag strut - collects seismic load from diaphragm
parts of bldg: Fp = Z*I*Cp*Wp; Cp from table 23J - horiz force factor

Wind pressure
p = Ce*Cq*qs*I - all from UBC

Ce = exposure (based on height) - Table 23G
Cq = pressure coefficient - Table 23H
method 1 (normal force method)
method 2 (projected area method)
qs = wind stagnation pressure @ ht. 30'
from basic wind speed - table 23F
I = importance
assemblies, I = 1.15
others, I = 1

Just as we gained a uniform, mathematical time, so also we gained a uniform, mathematical space. The change is evident in the evolution of the artist's techniques. Before the development of linear perspective during the Renaissance, space did not present itself to the artist independently of things; it was more like the qualitatively varying presence of things, and derived its local shape from them. This plastic quality of space, evident in so many medieval paintings, typically appears highly confused to us.—Steve Talbott, TECHNOLOGY, ALIENATION, AND FREEDOM

When I developed a hypothesis whereby two people look at an object, a measurement of its its apparent size to each person will vary, someone said, “That’s architecture.”